Gas Chromatography Richard S. Juvet, Jr., Department of Chemisfry and Chemical Engineering, University o f Illinois, Urbana, 111. 61 807 Stuart P. Cram, Department o f Chemistry, University o f Florida, Gainesville, Fla. 32607
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REVIEW surveys developments in the field of gas chromatography since publication of the last review in this series (325) and covers the years 1968-69. Gas chromatography continues to be one of the most active areas in analytical chemistry. A recent report by the American Chemical Society (103), based upon the first specialty choices of 80,614 practicing chemists and chemical engineers reporting t o the 1968 National Register of Scientific and Technical Personnel, showed that 16.070 of the analytical chemists list chromatographic analysis as their first specialty choice, a number greater than any other area of analytical chemistry. The marketing of gas chromatographic equipment remains very active with 94 models currently available in the United States from 30 different instrument manufacturers (302). Gas chromatographs are the most widely used on-stream analyzers in the chemical industry today, and between six and eight million dollars worth of process instruments were sold in the U. S. in 1969 (579). We estimate 2430 articles and major addresses directly involved with the theory, apparatus, and novel applications of gas chromatography were published in 1968 and this number exceeds 2250 in 1969 (548). As a point of interest, these estimates compare with a more accurate count of 2045 in 1967, 2175 in 1966, 2060 in 1965, and 1878 in 1964. Because of this vast literature, considerable selection was necessary in preparing this review. Technique-centered aspects are mainly considered and most such publications through November 1969 are noted.
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BOOKS AND REVIEWS
Books on gas chromatography published during this biennium include a comprehensive text by Schupp (597) written as Volume XI11 of Perry and Weissberger’s series on “Technique of Organic Chemistry,” and an excellent monograph edited by Ettre and McFadden on ancillary techniques of gas chromatography (186) which deals with the interfacing of gas chromatography with other instrumental methods such as mass spectrometry, infrared spectroscopy, NhIR and thin layer chromatography, as well as special techniques such as pyrolysis. A collection of eight critical and comprehensive reviews on important areas of gas chromatography was edited by Purnell
(554) as part of the Advances in -4nalytical Chemistry and Instrumentation Series. An English translation of Berezkin’s 1966 Russian monograph on “Analytical Reaction Gas Chromatography” has appeared ( S l ) , as has a Russian translation of Dal Nogare and Juvet’s comprehensive text (142) not previously referenced in this review series. Another Russian test, published too late for inclusion in the last review, is devoted t o gas adsorption chromatography and is authored by Kiselev and Yashin (359). “Instrumentation in Gas Chromatography” is the subject of a text edited by Krugers (378), and an English translation (674) with some revision of the second French edition of “Xanuel Pratique de Chromatographie en Phase Gazeuse” edited by Tranchant (671) was published recently. A programmed introduction to gas chromatography has been devised (521) in which a single principle is presented on each page, allowing the student to select the correct answer from several choices. The correct answer and discussion are presented on indexed pages appearing later in the book. The fifth edition of McNair and Bonelli’s introductory manual (464) was published in 1969. A laboratory handbook for chromatographic methods which includes a chapter on gas chromatography (470) and an elementary book for undergraduate students covering TLC, GC, and column chromatography have also appeared (57). Other texts on adsorption chromatography (622) and physical separation methods (726) include chapters on gas chromatographic separations. Four volumes of LIAdvancesin Chromatography” edited by Giddings and Keller were published during the biennium (288). Each of these volumes contains sections surveying important advances in gas chromatography as well as other chromatographic techniques. A number of monographs dealing with biomedical research applications of GC, sometimes combined with other techniques, include Volume 2 of “Lipid Chromatographic Analysis” edited by hlarinetti (446); “Gas Phase Chromatography of Steroids” edited by Eik-Nes and Horning (182); a paperback monograph, “High Resolution Gas Chromatography in Steroid Analysis: An Introduction to the Use for Clinical Purposes’’ by Kuppens (381); “Quantitative Gas-Liquid Chromatog-
raphy of Amino Acids in Proteins and Biological Substances. Macro, Semimicro, and Micro Methods” by Gehrke et al. (218); and Volume I1 of “Biomedical Applications of Gas Chromatography” edited by Szymanski (648). Monographs on environmental problems include “Environmental Pollution Instrumentation” edited by Chapman (101) and Volume I1 of “Air Pollution” edited by Stern (633) on analysis, monitoring, and surveying. “Characterization and Analysis of Polymers by Gas Chromatography” is the subject of a recent book by Stevens (635).
The proceedings of a number of major symposia which include papers on gas chromatography have been published in book form: the Seventh International Symposium on Gas Chromatography and Its Exploitation held in Copenhagen (871); the Fourth (804) and the Fifth (199) Biennial International Symposia on Chromatography and Electrophoresis held in Brussels by the Belgian Society of Pharmaceutical Sciences; and the proceedings of the 1969 Symposium on Advances in Chromatography held in Las Vegas (740). Published short reports of these and other symposia include the International Symposium in Copenhagen (174) ; the Symposium on Advances in Chromatography in Las Vegas ( 3 3 4 , the complete papers of which were published in the January through July 1969 issues of the Journal of Chromatographic Science; the IVth International Conference on Separation Methods with Special Reference to Chromatography held in Heidelberg (523), in which 27 of the 54 lectures presented dealt with GC; the 3rd All-Union Seminar on the theory and use of stationary phases held in Kiev, USSR (374); the Symposium on Gas Chromatography and Thin-Layer Chromatography held in Dublin a t a joint meeting of the Chemical Society, the Institute of Chemistry of Ireland, and the R I C (1.61); as well as informal symposia of the British Gas Chromatography Discussion Group (161, 417, 418, 531, 725). The 1969 applied review issue of ANALYTICAL CHEMISTRYcites several hundred references to applications of gas chromatography published during 1967 and 1968 in the fields of air pollution ( 9 ) , clinical chemistry (554), coatings (645), essential oils and related products (256), food (619), pesticide residues (664), petroleum (679),
ANALYTICAL CHEMISTRY, VOL. 42, NO. 5 , APRIL 1970
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pharmaceuticals and related drugs (518), rubber (706), and solid and gaseous fuels (1). Reviews on biochemical (187) and steroid (686) analysis; the chemical composition of tobacco and tobacco smoke (627); the pyrolysis of polymers (18) ; quantitative determination of carcinogenic hydrocarbons (688); coupling GC with mass spectrometry (685, 717 ) ,infrared spectrometers (214, 416), and chemical methods of qualitative identification (415); the kinetics of liquid phase reactions (42);and developments in the van Deemter rate theory (708) have also appeared. The Preston Technical Abstracts Co. (548) continues its excellent service to workers in the field of gas chromatography by issuing abstracts of all papers and major addresses, often within a matter of weeks following publication of the original article. As of January 1970, however, these abstracts will no longer be available on needle-sort punched cards but will be presented in bound booklet form carefully referenced to aid in literature searches. The abstracts are also now available on 16- or 35-mm microfilm reels or on microfilm reader cartridges and are used in combination with the Thermatrex Index System (548). The Journal o j Gas Chromatography expanded its scope to include research in other areas of chromatography in 1969 and changed its name to Journal of Chromatographic Science. Editor of the journal is Roy A. Keller and the Preston Technical Abstracts Co. continues as publisher (548). Another new journal of interest to gas chromatographers is entitled Chromatographia. This new international journal for rapid communication in chromatography and related techniques was first published in 1968 by Pergamon Press as a bimonthly journal but in 1969 became a monthly. Paper titles, summaries, and figure captions are published in English, German, and French. The 1967 (364) and 1968 (365) annual volumes of “Gas Chromatography Abstracts” edited by Knapman were published by the Gas Chromatography Discussion Group of the British Institute of Petroleum during this biennium. The 1969/1970 international chromatography guide, which is a useful directory of manufacturers and major sources of instruments, accessories, and supplies, has been compiled from questionnaire responses from nearly 400 companies around the world (311). The 1968 ASTM Book of Standards outlines recommended practice for general gas chromatography procedures (222) and presents its recommendation for nomenclature (223). The ASTM has also published the 2nd edition of its “Manual on Hydrocarbon Analysis” (443) sponsored by Committee D-2 on Petroleum Products and Lubricants. 2R
PACKED COLUMNS
Column Theory. Several theoretical and practical aspects of gas chromatographic isotherms and isobars have been reviewed by Tranchant (672). A discussion of the physicochemical basis of chromatography by Giddings (226) points out some unique theoretical problems. The number of papers which consider various aspects of H E T P indicates that the concept of the theoretical plate will be retained in the field of chromatography for some time. An equation combining the approximations of the plate theory and the kinetic theory was derived by TakAcs (652). This equation is claimed to be valid for packed, open tubular, or capillary columns and is compared with the van Deemter equation. A statistical evaluation of the errors involved in the determination of the constants in the van Deemter equation used a least squares fit of the constants to the function H = f(u)under optimum experimental conditions (269). A practical method for calculating the values of the constants in the H E T P equation was described (389). Arkenbout and Smith (11) present equations which show that both the theoretical plate and transfer unit are satisfactory units of column length when dealing with compounds which are difficult to separate or when the concentration of one component is small with respect to the other. Detailed mathematical approaches to mass balance, interfacial transfer, and the height equivalent to one transfer unit are included. A theoretical study of the relationships among resolution, free separation enthalpy, and separation efficiency has shown that the free separation enthalpy or the logarithm of the relative retention is approximately proportional to the resolution of a given solute pair (563). Experimental investigations of the role of H E T P have included an examination of the effect of column length (249, 367). Halasz (267) mathematically explained the H E T P dependence on column length based on his work with glass bead columns. He reported a marked increase in H E T P when two practically identical packed columns are coupled. This finding has been confirmed with capillary columns (249) and explained by the fact that the separation efficiency per meter is not constant (227). The nonadditivity of theoretical plates for columns which differ markedly in H E T P values, diameter, or composition was treated by Kwok, Snyder, and Sternberg (386) for liquid-solid chromatography and gel permeation as well as gas chromatography. However, the experimental results of Carmichael (89) show that a number of chromatographic columns in
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series give the same retention time and variance as a single column as long as the flow rates are identical in both cases. He states that the columns must be of the same cross-sectional area but each can be of arbitrary length and that the efficiency will be independent of the nature of the column packing, the input function, and the nature of the sample, The relationship between carrier gas velocity and the theoretical plate height has been investigated for a series of polar compounds on columns operated a t atmospheric and reduced outlet pressures (373). The theoretical expression for the decrease in plate height with increasing flow velocity (Reynolds number) and the anomalous increase of plate height with increasing mass distribution coefficient in the turbulent flow region were tested experimentally in a study with open tubular columns (592). The use of a digital computer was shown to be effective in obtaining more significant figures for H E T P and for on-line computation of the HETP value for each component of a mixture (713). I n this manner, a specific column may be evaluated as to its efficiency toward component types. The characterization of chromatographic peaks by their statistical moments has been effectively demonstrated (255). Off-line computer calculations were used for the detailed analysis of the peak shape and rapid methods for measuring the moments were described. By including the zeroth and first moments, the peak area and retention time, respectively, are also obtained. A foremost consideration in treating column efficiencv must be an examination of band broadening phenomena such as the study by Landault and Guiochon (389). They determined the contribution of gas compression to peak broadening and showed that results on packed capillary columns support the kinetic theory of GC as the resistance to mass transfer in the gas and liquid phase are consistent with values of the terms of the coupling constant. The distribution of residence times of solute molecules was calculated on the basis of the theory of stochastic processes and used the relationships for sorption kinetics to describe the density function of the residence time (533). This work accounted for axial transport in the mobile phase and lateral diffusion in the stationary phase, while Neier and Huber (468) showed the effect of maldistribution of solute in larger columns. A study of the influence of restrictive diffusion on the rate of solute migration has shown that the equilibrium theory does not hold for Molecular Sieve chromatography (151). Gas phase interdiffusion coefficients were determined by Hargrove (272) in a study of band broadening and the relationship of flow characteristics on glass bead and Chro-
mosorb W columns to the specific permeability of the column. The optimization of chromatographic conditions has been based on deriving a minimum HETP-for example, a threedimensional model to express the effect of column temperature and carrier gas flow on H E T P was developed (331). For capillary columns, Vlodavets (702) points out that the minimum plate height and separation time may be realized by increasing the outlet pressure and column length. The minimum analysis time for a given number of plates can be achieved by decreasing the column outlet pressure and operating a t the optimum flow rate. Hawkes (282) stated that the fastest analysis for all but the most difficult mixtures can be obtained with columns which are intrinsically inefficient or used inefficiently. This was not demonstrated experimentally and is of limited utility, because he assumed that the available inlet pressure and the speed of injection and readout proride the ultimate limitation in fast separations. Knox and Saleem (369) outlined kinetic conditions for optimum speed and resolution in gas and liquid chromatography. To characterize rapid separations effectively in terms of the number of effective plates per unit time, Halasz (265) has classified the properties of seven different types of columns to facilitate the selection of the optimal one. The separation mechanism of certain porous polymer columns was explained as an adsorption-desorption mechanism at lox carrier gas velocities for materials which are not soluble in phenylene oxide while a classical solubilization mechanism was found to be applicable in most cases (676). The physical measurements of Johnson and Barrall (318)indicate that the micropore structure of these beads is not significant in determining the separation characteristics. The theory of column retention has been approached by correlation of the mean values of pressure, linear velocity, and H E T P (695). The retention theory of GC was extended to finite solute concentrations by Conder and Purnell (116) by accounting for gas compressibility and gas imperfection and variation in the velocity of the mobile phase due to the flux of solute molecules across the interphase boundary. Rohrschneider (566) proposed a means of predicting retention data from the theory of regular solutions. Chemical structure was correlated with chromatographic retention (721) and extended by considering energy parameters (383). A mathematical model describing column behavior was proposed by Lai and Roth (386) to predict the column dead time. Later Masukawa and Kobayashi (449) developed a new method of estimating the free gas
volume which extrapolates the retention volumes of a series of perturbing gases back to that of a perfect gas. This was used to determine the amount of adsorption on the column (449), to study the continuity between gas-solid and gas-liquid equilibrium, and to evaluate vapor-liquid equilibrium (448). Liquid Phase. Langer and Sheehan (390) discussed the principles and theories used in choosing a liquid phase and in developing selective liquid phases, while deBruyn (149) compiled a table listing more than 60 common liquid phases along with such characteristics as chemical composition and manufacturer, polarity, temperature limitation, and practical applications. The evaluation of the polarity of liquid phases and its importance in effecting the retention of solutes has received considerable attention during the past two years. The separation characteristics of liquid phases can be defined successfully using the sixparameter method of Rohrschneider (664). By using the logarithm of the retention ratios of decane, benzene, nitromethane, ethanol, methyl ethyl ketone, and pyridine compared to noctane, Rohrschneider (565) calculated the retention ratios of 77 substances on 22 different liquid phases, presenting extensive tables of derived retention data and margins of error expected. Kovats (375) has studied the linear combination of interaction forces and has concluded that theoretically eight such interaction properties should exist. It is concluded that some of these forces strongly correlate with each other, thus reducing the eight characteristics to six as found empirically. The importance of charge-transfer interactions of the solute with certain liquid phases was confirmed (f34). -in equation has been derived (567) for calculating relative retention from a knowledge of the molar volumes and solubility parameters of the solutes and the internal pressure of the liquid phases. The polarity of a number of new silicone liquid phases-the OV series-was determined using the Rohrschneider system (640). Experimental data have been reported (430) showing a systematic deviation from linearity with polarity of the liquid phase in the relationship log t,‘ = f ( n ) , and a more exact expression was proposed correlating liquid phase polarity with solute retention and a coefficient suggested which is a true measure of polarity. Articles by Bonastre and Grenier (61, 62) on the polarity of liquid phases outline a method for the evaluation of retention indices and relative activity coefficients and present extensive data for alcohols and ketones on several different liquid phases, while Louis (423) evaluated the separating efficiency of 22 liquid phases toward alcohol, ester,
ketone, ether, and chlorinated alkane and alkene homologs. A graphical method (536) and one dependent upon frequency shifts in the infrared spectrum of solutes in various liquid phases (178) have been used to characterize the elution properties of liquid phases. Liquid phase bleeding from chromatographic columns has received some attention. An empirical expression for the amount of bleeding was tested (535) on 23 phthalate esters. The relationship between the vapor pressure of a liquid phase and the structure of the solid support in terms of internal pore volume, surface area, and distribution of pore radii was treated theoretically (377). The tendency for column bleeding has been determined for XE-60, DEGS, BDS, Versamid 900, FF.\P, DC-200, SF-96, DC-11, SE-30, and Carbowaxes 400, 1000, 1500, 20M, and 2011-TPA using mass spectrometry and thermogravimetry (462). Liptay et al. (412, 413) determined the maximum useful temperature for Carbowax 1500, Apiezon N and L, dimethylsulfolane, silicone oil 550, SE-30, polyethylene glycol adipate, Apikote 728, dibutyl phthalate, and combinations of these on Celite 545 and Chromosorb G using thermogravimetric or “derivatographic” methods. The excess surface adsorption of solutes a t the gas-liquid interface and the effect of this surface phenomenon on the retention index were examined (63). Evidence is presented (690) of a weak solute-solvent interaction of methyl groups in branched-chain compounds. Sharp discontinuities in retention and occasionally changes in elution order were reported (109) when liquid phases are used near their freezing point. A number of novel liquid phases have been investigated during this biennium. This includes further studies on the use of liquid crystals (347, 348, 446). Kelker and Schivizhoffen (348), in reviewing the use of liquid crystals as liquid phases, discussed the physical properties of the liquid crystal phases of importance in gas chromatography such as the useful temperature range, vapor pressure, coefficients of expansion, adhesive power, behavior in external fields, and thermodynamic aspects, among others. The nematic liquid phases, 4,4’-dimethoxyazoxybenzene, 4,4’-diethoxyazoxybenzene, and eutectic mixtures of these two, as well as p-methoxybenzal-p-butyryloxyaniline were used to investigate the pretransformation characteristics of mesophases and their relation to solubility for the solutes o-xylene, C7-Cl0alkanes, and certain chlorinated hydrocarbons (347). Liquid crystals were suggested (459) as one of several possible liquid phase systems in which solute retention might be made in-
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dependent of temperature, solvent volume increase with temperature being compensated by a decrease in partition coefficient with increasing temperature. Several authors have studied the effect on retention of adding inorganic electrolytes to liquid phases. Bighi and coworkers studied the influence on the retention of hydrocarbons and alcohols of dissolving LiCl (51) and LiC1, KCl, CsC1, and KOH (50) in Carbowax 400. Aliphatic hydrocarbons showed stronger salting out than aromatic hydrocarbons while primary alcohols showed a marked salting-out effect. Juvet and Pesek (324) also noted salting-out effects in a gas chromatographic study of the structures of nonvolatile nietal chelates in which the metal chelate is used as liquid phase. Copper complexes of 1 , l O phenanthroline, 2,2-dipyridine, and chinoline have also been studied as liquid phases (300). Thallium(1) nitrate in D E G or P E G 400 compares favorably in the separation of olefins and aromatic hydrocarbons with that achieved with d v e r nitrate-containing coluinns (27). Geiss et al. (220, 221) separated aromatic isomers and their hydrogenated products, phenols, and aromatic nitro- and bromo-compounds using metal halide, sulfate, and nitrate salts. Juvet, Shaw, and Khan (325) showed that alkali metal tetrachloroaluminate and tetrachloroferrate melts are useful liquid phases for the elution of metal halides and evaluated the separation mechanism a t work in these fused-salt systems. The use of liquid phases chemically bonded to the support has attracted considerable interest, since a reduction in column bleeding would be expected. These materials have particular promise as stationary phases in liquid chromatographic systems. h patent has been issued (658) for a packing material comprised of a crystalline support such as sepiolite, attapulgite, or vermiculite chemically bonded at the surface by a halide such as the dimethyloctadecylammonium and trimethyloctadecylammonium salts. Halasz (268) described applications for a packing material in which 3-hydroxypropionitrile was chemically bonded to the surface silanol groups of the porous glass, Porasil C (544). Other novel liquid phases include the use of water for the rapid separation of hydrocarbons a t temperatures as much as 300 "C below their boiling points (339, 340) ; moistened polystyrol for polar compounds including fatty acids (605); polyglycerol and its etherification and cyanoethylated products (193), particularly useful for the separation of fatty alcohols and glycols; poly(esteracetals) and poly(amide-acetals) of high thermal stability crosslinked during column conditioning (146) ; poly-m-
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phenoxylene, a liquid phase found useful in the analysis of polynuclear aromatics, benzpyrene, sterols, and trimethylsilyl sugar ethers (35); a series of polyoxyethylene glycols for polar compounds (190); and the ?-irradiation product of stilbene which is said to be comparable to Versamid 900 as a polar phase for the high temperature analysis of insecticides (177). A new polyester liquid phase prepared by condensation of maleic acid with diethylene glycol proved useful for the separation of methyl esters of fatty acids including the various cis and trans isomers of octadecadienoic acid (642). Sixty liquid phases were evaluated to establish the most useful of these for the elution of terpenes (29). A dual column system using OV-17 and ethylene glycol adipate columns was used by Gehrke et al. (219) for the resolution of 20 N-trifluoroacetyl n-butyl ester derivatives of protein amino acids. Silicone Dow-Corning 11 is recommended for the separation of pesticides (733). Janak and Hainova (307) claim that the separating efficiency and thermal stability of Czechoslovakian-made polyesters are equal or superior to those of certain Western-made polyesters of the same type. OV-17 is recommended (280) as a slightly polar general-purpose packing and is said to be more stable than SE30 at 300 "C. adjusting liquid phase polarity by mixing liquid phases continues to interest several workers. A FORTRAN program was developed (478) capable of selecting the best two-, three-, or fourphase columns for separation of a mixture of up to 50 solutes and evaluating the minimum necessary column length. The identification and molecular structure of solutes were established on the basis of shifts in retention when the liquid phase composition is varied for binary mixtures of n-tetradecane, 1,2,4-trichloroethylbenzene, and diethylphthalate, nonpolar, acceptor, and donor liquid phases, respectively (707). Relative activity coefficients of solutes in binary mixtures of the two liquid phases, p,p'-oxydipropionitrile and dibutyl maleate have been evaluated (560).
Further studies in low loaded columns also were conducted. Hawkes and Nyberg (283) studied column parameters for ultralow-loaded glass bead columns ranging in loading downward to 0.0049;b and found for Ballotini glass beads an increase in retention a t loadings less than O . O l l ~ oowing to the increasing importance of adsorption. Other authors (314) have noted adsorption of solutes on low-loaded columns. Elution of solutes 180 "C below their boiling points was accomplished with liquid phase loadings of 2 to 3y0on ground unglazed porcelain supports (37). Optimum liquid phase loadings of
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0.1 to 0.35% were found for textured glass beads (433, although loadings as high as 0.6% gave HETP values less than 1.0 mm. Solid Supports. Reaction kinetics involving the reaction of trioxane on TMS treated firebrick to form formaldehyde was shown (392) to be an effective means for studying the surface treatment of the solid support in GC. A Gas Chrom Q column showed no depolymerization of the trioxane. A later review (391) of the literature on GC column reactions pointed out the potentialities and limitations of such reactions. Urone and Parcher (519, 683) continued their investigation of support effects on retention volumes by measuring adsorption and distribution isotherms and showed that the retention volume is a function of the adsorption isotherm at a given solute concentration. The influence of substrate structure and surface porosity on the retention volume and the distribution of the liquid phase was investigated (543). For the diatomites and glasses with pore diameters greater than 600 A, elution peaks were symmetrical with minimum plate heights of less than 1 mm (200). At any given liquid loading, the minimum H E T P values for the controlled-pore glasses were equal t o or less than the diatomaceous earth supports. Kirkland (355) experimentally demonstrated that by varying the dimensions of the over-all particle and the thickness and porosity of the surface, spherical siliceous particles could be optimized for use in both gas and liquid chromatography to give very rapid separations. HETP values as low as 0.11 mm were obtained. Filbert and Hair (201, 202) have described most glass bead supports as having silanol groups and Ca2+ ions on the surface which may function as Lewis acid sites and cause adsorption of lone-pair donor molecules such as ketones and amines. Surface-leached sodium silicate glass beads were shown to give a better distribution of liquid phase by increased efficiency and peak symmetry a t o.3y0 liquid loading. Octoxy-, butoxy-, and benzoyl- derivatives of porous borosilicate glass were also superior to unmodified supports (732). Liquid loadings of less than 0.011% showed increasing adsorption, but loadings as low as 0.02yo were practical for minimum time analyses (283). The optimum loading of other surface-textured beads for the separation of pesticides and other mixtures was found to range between 0.1 and 0.35% (436). Russian workers have developed porous glass supports and evaluated the influence of the supports on partition coefficients, peak asymmetry, retention volumes, and HETP values of
polar substances (737). Theoretical work has related the vapor pressure lowering of a stationary phase to the structure of the support in terms of the internal pore volume, the surface area, and the distribution function of the pore radii (377). Improvements in polymeric solid supports have included thermal treatment (74, 578) to decrease the number of pores without altering the pore diameter and impregnating the support with tetrafluoroethylenevinylidene copolymer (71). Supina and Rose (640) compared a number of the Porapaks and Chromosorb porous polymers and report all of the polymers suitable for a wide variety of compounds except the application of Chromosorb 103 t o highly polar species. A new spherical, low density ceramic solid support was made from a high alumina, soda-lime-silica glass and found to compare well with other types of supports after deactivation with DZICS (95). The use of activated natural mordenite as a column packing was evaluated for small molecules, and when treated with HC1 or NaC1 gave separations comparable to the hIolecular Sieves (669, 670). The role of surface activity was shown to influence the relative retention due to selective trapping of solute molecules in the micropores of certain supports, such as Teflon (189). The adsorption errors reported by Jequier and Robin (314j for lightly loaded columns show that relative retention values varied until as much as 10% liquid phase was used on " I D S treated Chromosorb P. I n another study, Chromosorb M (HhIDS) was the only support found to give retention volumes which were independent over a thousandfold range of sample size when the adsorption errors were studied for a wide variety of solutes and supports (112). Endrin was chosen to demonstrate the relationship between decomposition and column temperature, since surface active sites on support media tend to promote the thermal-catalytic decomposition of certain moderately stable organic compounds. Surface-textured glass beads were found to be free from active sites according to this criterion (437). To complicate further the evaluation of the effect of the column support, experimental data obtained from a series of organophosphate peiticides indicate that variations in the density and adsorption characteristics from batch to batch of support material alter the analytical results (47). Adsorption Columns. Adsorption columns have been the subject of a number of theoretical treatments and physicochemical investigations, and laboratory applications have flourished by the dynamic demonstration of the utility of these columns. The
basic principles of adsorption chromatography and its application to the separation of organic compounds was published in a timely compendium by Snyder (622). Grubner (252) described the statistical moments theory for the solution of a system of partial differential equations which describes a model based on diffusion-controlled kinetics for gas-solid chromatography (GSC). A study of the influence of adsorption on the contribution to the plate height due to interparticle diffusion has shown that the normal plate height expression can still be used if the diffusion coefficient is modified in the case of linear adsorption (384). The value of the kinetic mass transfer term of the plate height equation was used by Vidal-;\ladjar and Guiochon (698) to determine experimentally the average desorption time for gas-solid partition chromatography. Snyder (621) presented the general theory of dispersion interactions in GSC and pointed out that they cannot be neglected, as is often assumed. I n an investigation of activated sorption, the H E T P values were found to be independent of the nature of the carrier gas by measuring the heat and energy of activation (306). A method for determining the absolute volume of the column packing material, the absolute density of the adsorbent, the dead volume of the column, and the heat of adsorption directly was developed (563). The para-, orthohydrogen conversion and Ht-Dz exchange reactions were used to investigate the physical and chemical adsorption of hydrogen on various aromatic alkali metal charge transfer complexes (303). Phillips (538) reviewed the modification of GSC supports. Examples were given to illustrate the application of supports modified with chemically inactive salts, salts which are capable of forming a chemical bond, metal complexes, and organic modifiers. The use of water vapor as a moderator for silica and alumina columns and the effect of temperature and moderator concentration on retention volumes, efficiency, and resolution were reported (602). Silica gel columns were the subject of a study of equilibrium isotherms (609) and used for the separation of H2 and Dz in capillary columns (476). Macroporous silica gels and aluminosilica gels were prepared for gas adsorption measurements @ I O ) , while improved separations were reported for silica gels pretreated by acid precipitation and dehydration, thereby modifying the surface area and packing density (297,298). A number of fixed gases were separated on silica gel, Molecular Sieve, and coupled columns (99). The &lolecular Sieves may also be modified, as
shown by Brunnock and Luke (77), to change the order of elution of the Cs naphthenes and paraffins. The effect of micropores on the retention volume and the peak shape was shown in comparison of 4A and 5A Molecular Sieves (503). h high precision G C was used t o measure changes in the retention time with flow rate and the increase in H E T P with temperature (603). The authors attributed the results to a kinetic effect and argue that since the mass transfer in the stationary phase is proportional to the square of the pore depth,a greater effective pore depth due to greater diffusivity a t higher temperatures could account for the observed increase in HETP. Measurement of the diffusion of inert gases in zeolites, mordenites, and faujasites by gas chromatography was reported to be a more suitable method for the measurement of adsorption and desorption rates than methods employing constant volume or constant pressure (175). Isomerization of hexene on zeolites was observed while measuring adsorption equilibria (534). Modification of aluminas with NazSO4 and Na3P04 varied the specific surface area and energies of adsorption and reduced the magnitude of nonspecific interactions (273). The suitability of packed capillary columns for the determination of the physicochemical characteristics of sorbents was shown by investigation of the surface area, catalytic properties, and heats of adsorption on various aluminas modified with HzO, NaOH, and squalene (644). Sorption studies of several alcohols (372) and cyclohexene (370) show good agreement with the heats of adsorption and the specific adsorption capacity determined by static methods. Hoffman and Evans (291) correlated experimental GSC data with the molecular characteristics of mass, atomic cross section, and composition for eight pure carrier gases. Their study shows that the molecular weight and structural types of hydrocarbons amenable to alumina separations are strongly influenced by the carrier gas selected. As an example of the application of the modified alumina columns, Russian workers (398) studied the inhibition mechanism of dehydrogenation and hydrogenation reactions of butane and butenes by GSC. The results of a detailed investigation of specific adsorptive interactions for several modified alumina columns were summarized by Brookman and Sawyer (73). The retention volume of salt modified alumina was found to be affected by specific adsorptive interactions caused by the pi-character of the sample molecule and its spacial geometry. The aromatic substituent effects on relative retention were treated in more detail in a later paper (74) for modified aluminas and Na2S04-deactivated porous
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silica beads. Macroporous aluminasilica gels were modified with pyridine bases for the separation of polar compounds (159). Both salt-modified alumina and porous silicabead columns were compared to show that the retention volume of a molecule can be predicted on the basis of the additive contribution of the functional groups to the free energy of adsorption (586). Optimum conditions for salt modification and/or silanization of Porasil C were described and the differential enthalpies, entropies, and free energy of adsorption for the functional groups of substituted hydrocarbons were measured (305). Sawyer and Brookman (586) also showed that the ideal adsorbent and column conditions may be predicted from the retention parameters for a group of saltmodified columns, and later reported that it was possible to use GSC to determine the molecular structures of cyclid unsaturated hydrocarbons (75). A good correlation was observed between the results obtained by GC techniques and static measurements for the determination of adsorption isotherms and heats of adsorption for steam and benzene on graphitized carbon black (38). This adsorbent has been used for the separation of polynuclear aromatic hydrocarbons (736), Cd hydrocarbons (357), and terpenes (358) and has been deposited on the walls of capillary columns for the separation of a number of isotopic molecules (242). Kiselev et al. (263), demonstrated improved separations on microporous charcoal (Saran type) made from polychlorovinyl. The use of crystallized organic compounds on graphitized carbon black was proposed (699). A study of the properties of these columns showed the adsorption enthalpy to be lower than on pure carbon black, permitting elution of samples at much lower temperatures (700). The rate of chemisorption of hydrogen on a nickel catalyst was measured in GSC columns (515). The same adsorbent was modified by hydrogen fluoride for the separation of alcohols and other oxygen-containing compounds (492). Water vapor was used as the carrier gas and HETP values of 2.5 mm were obtained in the study. Chromosorb P was modified with 10% CsCl and used for quantitative determinations of polyphenol mixtures by temperature programming (509). Alkali metal chlorides and nitrates have shown promise as selective adsorbents in GSC (509). Physical adsorption was found to be the predominant process as the elution order was dictated by electronic and polarization considerations, Carrier Gases. The characteristics of the common carrier gases (He, NB, HP,Ar) and their effects on column performance were reviewed (379, 598). The principles and applications of flow 6R
programming and techniques which involve changes in the mobile phase, such as vacancy chromatography, iteration chromatography, chromatography without carrier gas, and frontal adsorption analysis have been reviewed. Injectionless negative peak GC has been applied to the analysis of carrier gas impurities (232). I n this technique a disruption of the column equilibrium is induced so that a zone of purer carrier gas elutes to give a negative peak which can be qualitatively or semiquantitatively related to impurity concentration. An adsorption-desorption phenomenon appears to be the mechanism responsible for the negative peaks rather than a diffusion-controlled fractionation. Low pressure gas chromatography was compared to the normal flow pattern and found to give faster separations and higher resolution for very polar and nonpolar compounds as well as samples with low volatility (617). High pressure gas chromatography and chromatography with supercritical fluids promise to constitute an important and versatile separation technique. Giddings et al. (269) showed that dense gas chromatography offers the distinct advantage of being able to vary the solvent power of the mobile phase quickly over a wide range to fit the experimental conditions, obtaining greater speed of separation than in liquid chromatography because of reduced viscosity and increased diffusivity along with the advantage of using normal GC detectors. Pressures to 2000 atm were used to separate polymers and biological materials with molecular weights as high as 400,000 (463). Carbon dioxide was used as the mobile phase to separate a- and p-carotenes a t 40 "C (463). Ammonia, n-pentane, and isopropanol have also been used as carrier gases (616). Karayannis and Corwin (337, 338) used CC12Fz as a carrier gas up to pressures of 2800 psi for the separation of porphyrins, metalloporphyrins, and various metal chelates. Column efficiency studies by Sie and Rijnders (615) indicate that the most important contributions to plate height are associated with the nonuniformity of flow and intraparticle diffusion. Column permeability in the laminar and turbulent region of flow, the effect of pressure on the constants of the van Deemter equation, and variation of column efficiency with pressure were also discussed. Solid adsorbents (617) and porous polymer supports (613) have been successfully used with supercritical fluid mobile phases. A number of workers (138, 143, 528) have measured the second virial coefficients for solutes in both inert and hydrocarbon carrier gases by gas chromatography. Gainey and Young (217) established the effect of chain length on activity coefficients and determined the
ANALYTICAL CHEMISTRY, VOL. 42, NO. 5, APRIL 1970
mixed second virial coefficient of benzene and carrier gas. Sample Introduction. The theoretical influence of the injection step on resolution and the accuracy of qualitative analysis on high resolution columns as well as the linearity of streamsplitting injection devices have been discussed by Cramers (124). Ashley ( 1 7 ) developed a general relationship between the gas chromatographic sample input profile and the response shapes which allows computation of the effects of extracolumn instrumentation and a comparison of experimental parameters, The practical aspects of sampling such as the rate of sample injection, the effect of sample volume and mode of introduction on retention time, injection port design, checking the linearity of stream splitters, and on-column injection were reviewed (119, 869). Oberholtzer and Rogers (502) critically evaluated the precision of a number of commercially available gassampling valves and the exponential dilution flask and reported a relative precision of f 0.0870 for the peak area. Prevolatilization losses, syringe discharge and withdrawal effects, and temperature gradients across a syringe are among the factors limiting the reproducibility of syringe injections (540). Teflon permeation tubes were evaluated as sampling systems for SOz by independent measurements (645), and the effect of thermal hysteresis of the permeability of the Teflon was discussed (590). Injection of samples ranging from 5 to 100 nanoliters has been reported by Sanz (582) and should be of interest to those using low capacity columns. .4 liquid sampler which uses a microliter syringe was developed for collecting pressurized samples from sample bombs and explosive mixtures (153), while a gas valve was designed to operate a t 25OOC and pressures up t o 50 psi by not using sliding or rotating seals (145). The problems associated with rubber septums in injection ports become more pronounced a t these more extreme conditions and thus systems were designed to facilitate the replacement of septums and to minimize the amount of exposed surface to material in the inlet (461). A procedure for elimination of ghost or memory peaks was suggested by Kishimoto and Kinoshita (360). The automation of solid sampling techniques (274) and of temperature programming the injection port for solid samples is of interest for compounds which are thermally stable (401, 438, 716). Solid samplers are also recommended for materials such as pine needles and radiolysis reaction products which contain volatile components but leave solid residues (28, 562). These systems must be easily cleaned and not
exhibit memory effects or effect peak shapes or areas. Arc-melting (329)and a silicon fusion technique (344) have been suggested for the determination of oxygen, nitrogen, and other gases in metals such as titanium. Lynn (433)patented a sampling system which atomizes liquid samples prior to vaporization in a chamber preceding the column. Vaporization chambers have also been used to bring the vapor pressure of the sample in the carrier gas stream up to its saturated vapor pressure a t the temperature of the column and thereby obviate the disadvantages of flash vaporization (620). The advantages of sampling valves are evident and have given rise to an increased number of patents for chromatographic sampling and switching valves. Valves developed are modifications of the sliding seal type (276),the rotary switching design (333), and the magnetic or pneumatically actuated flexible diaphragm type (647, 668). Todd and Courneya (667) considered the important characteristics of internal volume and dead space, peak trailing, and leakage. Auxiliary techniques were reported to ensure constant volume and pressure in an effort to increase the precision of gas sampling (279). For direct sampling into high resolution and capillary columns, samples may be diluted with a nonvolatile solvent and injected into a small packed precolumn (126). Microcooling traps have been employed with packed or capillary columns (724) and a short section of the capillary column itself has been used (SO). The injected sample is condensed in the trap and then heated to release the sample rapidly. This technique was shown to give decreased values of H E T P and was applied to steroid analyses in complex natural samples (261). Injection systems for preparative columns which minimize pressure surges by heating the injected fluid to just below the boiling point (649)or which reduce the carrier gas pressure a t the inlet during sampling (313) were shown to be effective in introducing samples of much larger magnitudes. Trapping. Condensation on thinwalled glass capillaries (82) or small diameter stainless steel traps (605,689) proved useful for subsequent mass spectroscopic analysis. Infrared analyses of condensate trapped in glass tubing traps were run on samples as small as 0.20 fig (139). Infrared fraction trap-gas cells (26)eliminate sample transfer and have been shown to have better than 90% collection efficiency. Samples trapped in 6-cm c tpillary tubes have also been employed in standard NMR tubes for high resolution spectroscopic analysis (472). Factors affxting the efficiency of collection in glass melting point tubes
indicate that lowering the detector temperature gives significantly higher recoveries (IS). Fractions, including amount,s in the submicrogram range, may be collected on short GC columns and then eluted by rapidly heating the packing (48,607). King and O’Connor (363) devised new techniques to solve the problems of aerosol formation. Developments in mechanical devices were described, such as the use of time-delay circuits to prevent triggering the collection system on spurious peaks (IN), and a high temperature manifold for preparative GC (87). Bache and Lisk (22) collected organic eluents from a preparative GC unit in a closed trapping system which involved adsorption of the compounds in base during their elution with COZ carrier gas. OPEN TUBULAR COLUMNS
An excellent detailed review of glass capillary technology, including methods of modifying capillary walls so as to produce a better surface for retaining liquid phases, has been authored by Grob (248). The influence on the resolution of various operating parameters such as liquid phase film thickness, column temperature, column length, and carrier gas flow rate was thoroughly studied (264)for conventional capillary columns, larger open tubular columns, and S.C.O.T. columns. Pretorius and coworkers (692) studied the effect of flow velocity and mass distribution coefficient on the theoretical plate height in the turbulent flow region in open tubular columns a t Reynolds numbers ranging from ca. 500 to 1500. Several authors (184,249,‘702)have found that the minimum H E T P value and the corresponding optimum flow rate decrease as the column length is increased. Ettre (184) demonstrated that it is experimentally advantageous to use a longer open tubular column a t higher velocity than a shorter column operated at the optimum flow rate. Two innovations in open tubular column technology include the “sandwiched capillary columns” suggested by Liberti et al. (dli),in which the fractionating medium is a carbon or graphite yarn thread contained inside the capillary, and the use of an open cell polymeric foam material (IS%’), such as natural and synthetic elastomers, extending from the internal wall of the column inwardly toward the center, thereby providing a greatly increased surface area and preventing laminar flow velocities. Interest has continued in the use of loosely packed open tubular columns. Comparative tests between loosely packed capillary columns, 350 cm in length, and conventionally prepared open tubular columns, 900 cm in length, showed similar ana-
lytical speed and resolution (286). A thorough theoretical and experimental study of packed capillary columns with diameters ranging between 0.45 and 4 mm, mixtures of Chromosorb P support with particle sizes varying between 60 to 80 mesh and 125 to 160 mesh, and column length ranging from 9.7 to 14.1 meters has been made by Landault and Guiochon (388). Permeabilities ten times larger than conventional packed capillary columns prepared with the same support particles were found and plate densities as high as 2500 per meter were attained. Thick layer graphitized carbon black open tubular columns are recommended by Liberti and coworkers (241,24.2) for the separation of hydrogenated and deuterated analogs, and a method for preparation of these columns is outlined. A procedure for coating glass capillary walls with various supports such as maize starch, pollen, alumina, or silica coated with liquid phases was presented by Kaiser (326). Grant (243,244) has also detailed the preparation of porous layer open tubular (PLOT) glass columns which contain a layer of solid support on the walls of the capillary, greatly increasing the column capacity and a t the same time producing columns of high permeability. PLOT columns are prepared by loosely packing a borosilicate tubing with sieved diatomaceous earth containing lithium chloride as a binding agent, inserting a fine tungsten wire in the tubing, and drawing the tube to capillary dimensions over the wire to leave an orifice of the wire diameter. Golay (236,237) extended and refined his rate equation for PLOT columns. Treatment of the inner surface of glass capillaries with gaseous chloro- or fluorohydrocarbons under conditions producing corrosive mixtures is said to have the advantages that the capillaries are filled only with gas, the composition of the corrosive mixture can be accurately controlled, and the reaction products are either solid or gaseous (496). A method for enhancing the structure of the inner surface of metal capillaries has also been proposed (622),while a static procedure for coating the walls of glass capillary columns is said to give coating efficiencies better than the more commonly used dynamic methods (64). I n addition to the coating techniques outlined above, a number of other developments associated with open tubular column technology have appeared during this biennium. An ultrasonic method for cleaning used open tubular stainless steel columns prior to recoating was recommended (397). A system was described for dead-volume-free connection of glass capillary columns to commercial gas chromatographs (106). An improvement in resolution and apparent column efficiency was obtained by injection of the solute into a cryo-
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genic microtrap near the column inlet, followed by rapid heating of the trapped sample to desorb and vaporize it (30). A somewhat similar procedure, developed independently by Cramers and van Kessel (126), involves diluting the sample with a nonvolatile solvent and introducing the mixture with a standard microsyringe into a small packed precolumn equipped with a refrigeration device for concentrating the sample. Improved resolution was demonstrated for C1-C5 hydrocarbons by trapping the sample in one loop of the chromatographic column itself immersed in liquid nitrogen followed by warming (724). A method for collecting fractions eluted from packed columns and transferring to capillary columns was also proposed (589). ilckman and Hooper (S) noted a retarding “load effect” on the retention of adjacent later-eluting] structurally-similar isomers which is absent for dissimilar solutes. Guiochon and coworkers (144) developed a method which may find use in searching for malfunctions in capillary column units and which is based on measurement of variations in efficiency of the system for very rapidly eluted peaks where efficien:y is dependent only on column 1e.igth and diameter and not on temperature or nature of the carrier gas or solute. A theoretical description of programmed pressure or programmed flow GC in open tubular columns was presented (S49), and the method was used for separation of the components of lemon oil (440). Continuous infrared scanning of the effluents from an open tubular column using an infrared microanalyzer (36) and various types of electron-capture detectors (154) were evaluated for use with capillary columns. A few novel applications of open tubular columns are worthy of mention. Cartoni and Possanzini (91) separated the nitrogen isotopes using an etched glass capillary column cooled to liquid nitrogen temperatures and a carrier gas mixture composed of 55% helium and 45y0 carbon monoxide] and further studies by Mohnke and coworkers (477) were reported on the analysis of isotopic mixtures of hydrogen using capillary columns with a silica coating 20 microns thick and a novel electrolytic conductivity detector. Saturated and unsaturated CS to Cs hydrocarbon mixtures were separated on capillary columns coated with liquid phases containing silver nitrate (741), and the diastereoisomers of pristanic acid in the form of ~r methyl esters in herring oil and butterfat were separated (4). Finally, workers a t Shell Oil Co. have succeeded in separating approximately 240 C3-C,2 hydrocarbons in full-range gasoline using capillary columns with both programmed temperature and programmed inlet pressure (580). Of these compounds 180 have been identified. 8R
0
DETECTORS
Two comprehensive descriptions of various types of detectors and their characteristics were published in 1968 by Johns and Sternberg (316) and Guichard and Buzon (257). The diverse applications of GC detectors include examination of the lunar samples from Apollo 11, using a multiplicity of detectors (431) * Three principal developments in detector functionality should be noted. The principle of molecular multiplication discussed by Martin, Scott, and Wilkins (444) may be useful in extending the lower limit of detection. The basic limitations of the molecular multiplier have not yet been determined; they will depend ultimately on the noise level of the chemical multiplier itself. Second, it was shown by Obst (504) that phase modulation can be obtained in a GC detector by affecting a parameter that affects the run-through time of the components in the column. The carrier gas flow rate was modulated to provide a sinusoidal sample injection pattern using a wave generator. Third, a palladium transmodulator was designed to transfer the gas or separated column effluent to a second carrier stream which was kept a t a constant flow rate chosen to be optimum for the performance of the detector (426). With this development, sensitivities of thermal conductivity and ionization cross-section detectors were increased up to 40 times. -4 new, general, fast, and accurate method of preparation of a steady flow of gases for detector calibration can be used in all concentration ranges, and for traces as well as major components (183). The testing of detector linearity was described (466). Thermal Conductivity. The influence of various factors on the sensitivity and performance and the conditions for achieving maximum reproducibility for the thermal conductivity (TC) detection of gases were developed theoretically and verified experimentally (S22). An expression for the relative molar response of the solutes with the TC detector was formulated and a relationship derived on the basis of heat capacity effects between the total amount of a substance in a chromatographic zone and the recorded peak area (494). This relationship permits the elucidation of the effects of operating parameters on the detector response, the relative molar response, and it can be used to explain certain anomalies such as peak distortion and peak tipping. False peaks occasionally observed may be caused by dead space between the column and the thermal conductivity detector and composite columns which have different coefficients of distribution for gaseous components, according to Russian workers
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(8). Anomalous negative peaks which appeared in trace GC analyses were attributed to the phenomenon of vacancy chromatography (93). I n their study of the sources of error and the reproducibility of response of the TC detector in quantitative GC, Goedert and Guiochon (25.4) carefully evaluated the effects influencing the detector response and constructed a unit giving a standard deviation of 0.0005 for the peak height and area. Their results show it is possible to achieve a much higher level of accuracy than is obtained in current practice if experimental parameters such as inlet and outlet pressures are properly controlled. A group in Poland (706) explained the application of corrective coefficients in quantitative GC analysis with T C detectors. A study to establish detection limits and operating conditions for attaining maximum practical sensitivity for the trace determinations of organic and inorganic gases was reported by Green (246). By operating two different detectors in series, C/H ratios were determined for elemental analyses (208). Buhl (79) gives an operational description of thermistors in GC and treats their behavior theoretically. Sources of noise and the effects determining the signal-to-noise ratio are also described in this work. The response of the thermistor detector in gases of low thermal conductivity shows anomalous behavior over the entire flow range measured and results in peaks not being detected a t certain flow rates (527). The adverse effects of using hydrogen carrier gas with thermistor detectors is well known; thus, double-coated thermistors were suggested and evaluated for process GC (120). The accuracy and precision of the gas density balance for weight per cent and molecular weight determinations were re-evaluated in a careful study (712). The optimum ratio of reference to measuring gas flow rates for maximum response was determined and the viscosity and heat capacity were found to be predominant properties of the reference gases which affected the cell response. Creitz (128) designed a gas density balance using hot-wire anemometers as sensing elements and found them to be extremely sensitive but considerably less sensitive than some theoretical calculations indicate. Flow velocities of 1.4 x IO-* cm per second, corresponding to a density difference of 5 x gram per cmal were measured (127). The balance was used for the quantitative analysis of gas mixtures without prior separation of the components (687). The method requires that the component of interest be a major component in the mixture and have a molecular weight considerably different from the other components.
The advantages of the gas density balance for production control as either a continuous analyzer or directly as a detector were presented (260). Ionization. Knapp (366) reviewed the history, instrumental variations, and behavior of the flame ionization detector (FID) and showed that current amplification was preferable to voltage amplification. A second paper (367) discussed detector linearity, detector noise and its limitations and the current-voltage relationships in the associated electronics; and electrometer specifications and performance were discussed (368). Gill and Hartmann (231) compared the characteristics of GC electrometers and the effect of electrode shape, polarization, burner jet diameter, and flow rates of the F I D using a number of performance factors. Modifications of flame detector design include extending the usable temperature range without increasing secondary emission (649), the development of an efficient horizontal flame detector which featured low noise and minimum dead volume (501), and cryogenic trapping of impurities in compressed gases to increase the detector sensitivity by a factor of 2 (714 ) . By using the F I D with a flow-through thermal gravimetric analysis sample cell, vapor pressures were measured under chromatographic conditions (181). McCoy and Cram (458) designed a selective F I D which uses microelectrodes and extremely high electrostatic field gradients. The differential signal between the analytical flame and a reference fluid stream was used to characterize the composition of the column effluent (110). To standardize the response characteristics of the F I D , Ackman (2) suggested that 4-methyl-4methoxy-2-pentanone be used for interlaboratory comparisons. The low response to CS, in the F I D was studied and found to be due to preoxidation in the flame (162). The linear (150) and nonlinear (328) ranges of the F I D have been considered quantitatively. Oster and Oppermann (510) found excellent detector linearity if considerable care was given to the construction of the detector. They point out that dynamic testing of the F I D for linearity is not a suitable technique, as the linearity is likely to be limited by the injection, column, and flow lines, Instrumentation, detector response studies, and applications of the thermionic detector have flourished and indicate a great deal of interest in this detector. Karmen (341) studied the detector mechanism and found that the ionization of the alkali metal was increased in the presence of phosphorus and that halogens increased the volatilization of sodium from the source. Page and Woolley (516) used a multitubular burner with a cesium source and suggested the mechanism for the deter-
mination of phosphorus was disequilibration in the flame gases, and therefore the use of a large burner port and an increased Hz/N2 ratio would increase the hydrogen atom disequilibrium and the sensitivity. Pressed alkali salt tips around the flame jet have been operated for weeks without replacement and gave good sensitivity, stability, and signal-tonoise ratio for this detector when all other design considerations were optimized (156, 164). Nowak and Malmstadt (499) described a versatile and inexpensive ionization detector system for rapid conversion from flame ionization to sodium thermionic to electroncapture modes. The stacked flame detector design was adapted to continuous monitoring of trace organophosphorus compounds in air (546). Six different designs of the alkali source and 13 anode configurations have been evaluated, and a lower limit of detection of 1 pg for an organophosphorus pesticide was found using RbzSOd (152). Similar results with RbzSOd were obtained by Hartmann (276) for organic nitrogen compounds. The increased sensitivity of the thermionic detector over the flame detector of about 100 times for chlorine (111) and up to 3000 times for phosphorus was found desirable in pesticide analyses (34, 171, 345, 576, 577). Studies with triazine herbicides, chlorinated insecticides, and insecticide phosphate esters showed that KzS04, Rb2S04, and Cs2SOd gave the same effect when used as sintered salt tips (177). Dressler and Janak (166, 167) reported the selective determination of volatile sulfur compounds with a single flame thermionic detector, and the ionization efficiencies of a number of sulfur compounds were established. Differences in response level and profile were used to discriminate among volatile P, N, C, C1, and S containing compounds (165). The design of the electron-capture (EC) detector as it affects detector performance, the procedure for extending the linear dynamic range, and applications and potentialities of the EC detector were presented by Lovelock (425). Fenimore, Zlatkis, and Wentworth (198) extended the linear dynamic range by developing an analog converter in order to generate peaks which accurately represent the sample concentration. I n a study of the effect of scavenger gas on the efficiency and sensitivity of the detector, Devaux and Guiochon (154) found that higher sensitivity can be obtained with a miniaturized EC detector operated in conjunction with a capillary column than with a conventional packed column. Their work also shows that EC detectors are concentration-sensitive (155). Studies of the standing current in the pulsed and DC modes show that the
extent of detector contamination can be quantitatively estimated from an equation derived for the standing current in the DC mode (595). Relative sensitivity data were obtained for substituted benzenes for estimating the quantitative contribution of aryl substituent groups to sensitivity values and to evaluate the efficacy of a multiple linear regression model (739). The characteristics and parameters of the cross-section detector have been reported for Ha, KrB5,and NP3 sources (396). Combination of an electric discharge and UV lamp as the ionization source for the EC detector was patented (59)*
The optimum design of a photoionization detector was studied by Price (550) and its performance compared to that of other GC detectors, and ionization potentials and relative response values were tabulated for a large number of compounds (551). The general theory of the argon and helium detectors was discussed in terms of the effect of impurities on the production efficiency of metastable atoms (571). High field strengths were found to increase the detectors sensitivity through a combination of avalanche excitation of the carrier gas atoms and acceleration of secondary electrons to energies sufficient to ionize gas atoms directly (277). Variation in the response of the argon ionization detector with polarizing voltage was used to explain the appearance of positive and negative peaks (289). Experimental data for the argon and cross-section type detectors were obtained with model mixtures to study possibilities of increasing the sensitivity (594). A study of the Penning effect in ionization detectors indicates that the helium ionization detector is 10 to 60 times more sensitive if it is operated a t about 15 torr (520). The helium ionization detector has found application to the determination of atmospheric gases (238) and pollutants (94). The third electrode in the argon triode detector was shown to be significant in decreasing the backgound current caused by ionization of the carrier gas (596). The analytical relationships and properties of the detector were discussed. Lovelock (424) described the construction and operation of a detector which responds to the U' value -Le., the energy required to produce an ion pair in a gas-and has called this the W value detector. Although the detector is insensitive, it is useful for measuring high concentrations of vapors in air and is completely insensitive to large changes in temperature, pressure, and gas flow. Combinations of detectors, such as the FID-EC-thermionic detector combination described by Otte (511), were developed for qualitative characteri-
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zation. The flame ionization and thermionic detectors were coupled into a single unit (308, 643) and operated in a dual-channel mode by adjusting the detectors so each give the same response for organic carbon (561). Multiple detectors were also used to obtain selective detection by using reaction columns placed in series with the detectors (215). Miscellaneous. The very large diversity of detectors which have been investigated for the measurement step in GC indicates the breadth of analytical interest in sensitivity, and specificity and a realization of the compatibility of G C with other instrumental and physical methods of measurement. Nonionization detectors and their use in GC were reviewed by Winefordner and Glenn in the “Advances in Chromatography” series (727). Spectroscopic detectors such as flame emission and atomic absorption were interfaced to a GC for the specific detection of silicon (479). The limits of detection for the flame emission GC detector were approximated from limiting concentrations in atomic flame spectrometry (728) and applied to the analysis of permanent gases (512). A spectrofluorometer was combined with GC by absorbing fluorescent materials in a flowing stream of ethanol (65). Emission spectroscopy with a high frequency discharge source was used at the column outlet for organic analyses (330). The role of selective detectors and application of the flame photometric detector (FPD), as an example, was reviewed by O’Donne11 (506). Absolute calibration of the FPD for sub-ppm analyses with permeation tubes was studied over three decades at the ppm level (637). Bowman and Beroza (66) used the response ratio of a dual-channel F P D to calculate the atomic S/P ratio for pesticide analyses. Photometric measurement of a sodium-sensitized thermionic detector was shown by Kowak and Malmstadt to be highly selective and sensitive (497, 498). By varying the hydrogen flow rate in a copper-sensitized FPD, Bowman and Beroza (69) were able to differentiate among C1, Br, and I compounds. Various methods of introducing Cu (as CuO) into the flame photometric detector were tested to find the minimum detectable amount of chlorine by the Beilstein flame test (262). Response of the detector was found to be proportional to the oxygen concentration in the flame. A less selective F P D detector is the flame luminescence intensification and quenching detector which measures changes in the background luminescence of CS2 (130). The flame photometric detector has a wide range of applicability, as shown by its utilization for the analysis of natural products such as corn and 10R
grass (67‘), citrus oils (636), and milk and corn silage (68). Braman and Dynako (70) demonstrated that the flow-through, direct current discharge emission detector had good sensitivity, and backflow was prevented in the design of Sternberg (634). A simple glow discharge cell (188) and a resonance corona detector (645) were the subjects of preliminary reports. A selective and sensitive microwave helium plasma coupled to a GC column was successfully applied by Bache and Lisk to the analysis of sulfur-, halogen-, and phosphorus-containing pesticides (20, 21, 23) and drugs (19). With some modifications, the microwave emission detector may be used t o scan continuously the emission spectra of polyatomic organic compounds in a continuous flow system (39). The characteristics of a high frequency discharge cell make it particularly advantageous for gas chromatographic analysis at atmospheric pressure and low flow rates. The characteristics of this detector were described by Lambert (387), and Williams and Winefordner (722, 723) measured the analytical sensitivity for a number of fixed and hydrocarbon gases. An electrodeless discharge detector was compared with the thermal conductivity detector (If?), but was found to have a limit of detection of 0.1 pmole and a linear response limited to a tenfold variation in sample concentration ( 1 4 , 15).
A number of other “on-line” GC detectors have been investigated and perhaps their full potential is yet to be realized-e.g., the ultrasonic detector which has a wide range of application with subnanogram sensitivity (947). This detector was discussed by Porkert (541). Theoretical aspects of its molecular specificity were presented in terms of its characteristic relaxation behavior (429). The dynamic effect of gas flow through a pneumatic resistor was measured by the pneumatic GC detector (493). Another pneumatic detector is the pneumatic jet amplifier, which is a combination of the dynamic processes taking place upon the meeting of two jets and of the differential caused by the difference between the carrier gas and the eluted component density (678). A detector based on thermal adsorption and desorption was found to have a sensitivity of about that of the thermal conductivity detector and a response which was specific but not linear (661). Column bleed caused detector contamination, and lower column temperatures than are often used were recommended (524). King (351, 352) described the piezoelectric quartz crystal resonators as sorption detectors. The detectors are especially sensitive to
ANALYTICAL CHEMISTRY, VOL. 42, NO. 5, APRIL 1970
higher boiling solutes and may be arranged to give the solute concentration and information concerning solute polarity and boiling point instantaneously as a GC peak elutes. By using preferential adsorption, overlapping peaks were analyzed (581). Semiconductive thinfilm detectors have been used for some time, but silicon diodes have now been shown to be effective without special preparation (180). The working relationships and characteristics of semiconductor thin film detectors were reported by Seiyama and Kagawa (606). Coulson (122) reviewed the microcoulometric, electrolytic conductivity, and coulometer detectors in terms of sample type, sensitivity, and specificity. Improvements in the instrumentation of the microcoulometric detector and the effect of flow rate on the sulfur and chloride response were reported (258). Gunther and Barkley (261) bypassed the GC column to measure total chloride or total sulfur with the detector. Xpplications of the detector ranged from sulfur analyses in petroleum (168) and plant and animal tissues (526), to chloride in soil (525), potatoes (ZdO), and eggs (585),to nitrogen in corn (121), and to hydrogen in organic substances (107). An electrolytic conductivity detector was used with a capillary column for H2/D2 analyses (477). The nickel (11)-pyridine system was used to characterize the polarographic detector (689), and Cremer, Gruber, and Huck (129) illustrated the principle of the “fuel cell detector” for the GC analyses of alcohols and aldehydes. Readout. Innovations in analog modes of readout have included a logarithmic electrometer for automatic attenuation ( 1 0 4 , the use of R C networks to improve peak reproduction (380),and “wide range zero shifting” to detect shoulders on large GC peaks (405). The significance of the characteristics of potentiometric recorders in quantitative analysis was described by Carter (90). Hay reviewed the basic faults that might be encountered with a recorder (284) and suggested tests and remedies for the electrical characteristics of a recorder (285). Construction of a peak generator was described to allow repeated study of the external parameters affecting peak area integration (319). Wade and Cram (704) described the quantitative interpretation of semilogarithmic gas chromatographic data. The analytical implications of this mode of readout were discussed as well as methods of choosing the base line for peak area integration. Nikkelsen’s (471) treatment of the magnitude of the sources of error in GC includes both chemical and hardware effects. The recogcition of poorly resolved peaks by differentiating the detector output was used for locating shoulders (SSW), and,
in some cases, quantitative peak area calculations may be made (46). The application and characteristics of digital integrators to gas chromatography were reviewed by Jones (321) and Karohl (343). Frazer (211) described data acquisition with a small laboratory computer] while Levy et al. (404), and others (233, 263) discussed data reduction with the computer for generating reports of the analytical results. The paper by Hancock and Lichtenstein (270) presents a cursory treatment of the practical problems of data processing. il symposium on Computer Automation of hnalytical Gas Chromatography a t the 158th Meeting of the American Chemical Society held at New York in September 1969 presented a number of digital electronic systems for data acquisition and reduction and these papers are published in the December 1969 and January 1970 issues of Journal of Chromatographic Science. Baumann and Tao (33) showed the effect of slope sensitivity, filtering, and base line correction rate on the accuracy of data obtained from digital integrators. A time-shared computer system and the computer interfacing were described for on-line GC data acquisition (460). Off-line data reduction from magnetic tape was also evaluated (608). A variable function generator which provides a compensating signal to simulate a changing base line due to column bleed was developed for base line compensation during integration (403). Both analog and digital differentiation techniques have been used for more accurate base line extrapolation under a peak (342). Gas chromatographic data reduction was shown to be feasible through several levels of computer hardward, but the ideal situation was described as the coupling of small computers, which perform the direct data reduction, to a time-sharing service which will carry out the necessary data interpretation and calculations (32). Westerberg (718 ) presented an algorithm for the realtime sampling of several chromatographs which permits periodic input while using different input rates for different instruments. A program primarily designed for qualitative identification used several sources of retention data (40). The design and experimental use of programs for computer resolution of unresolved chromatograms was described by a number of workers (78). Littlewood et al. (420) used an iterative curve-fitting routine, and Gladney et al. (2SS),used a least-squares calculation. An inve-tigation of the influence of peak overlapping on the accuracy of GC results indicated that in the case of partial overlap, measurement of the peak height was to be preferred to
integration] and measurements of the peak height with reference to the base line gave more accurate results than the use of an arbitrary separation line (481). Westerberg (719) discussed the detection and resolution of peaks in the nonbase line segments of a trace and a method suitable for handling several concurrently operating on-line gas chromatographs with the CDC 1700 computer. QUANTITATIVE ANALYSIS AND INSTRUMENTATION INTERFACING
Quantitative Studies. Reviews outlining general considerations in quantitative analysis have appeared in French (399) and Polish (626). Deans (147) reviewed the errors affecting the accuracy of quantitative GC results and concluded that variable bias is one of the major potential sources of error because it is difficult to detect. Factors affecting the height-width integration technique of peak area measurement were investigated by Ball, Harris, and Habgood (25) with special emphasis on choosing the optimum position a t which to measure width. It was concluded that sharp Gaussian peaks have optimum width position close to the base line, while the widths of flat, broad peaks are better measured close to the half height, and the width at one-fourth the height is a good compromise when a number of variously shaped peaks are involved. These same authors ($4) earlier showed that peak height measurements are much more precise than peak height-width area methods when certain factors are controlled to obtain maximum precision. A quantitative method called the chronometrical method based on careful measurement of peak width with a stopwatch was suggested for use where an integrator is not available (80). Goedert and Guiochon (234) showed that catharometer response depends on carrier gas mass flow rate, carrier gas pressure in the detector, bridge current, detector temperature, and sample mass, and built an instrument in which most of these factors are closely controlled. Quantitative problems with the flame ionization detector in flow-programmed gas chromatography caused by the continual change in the ratio of carrier gas to hydrogen during analysis were considered by Levy et al. (410). Mathematical statistical considerations for area determination of asymmetric peaks (573) and a correlation analysis of seven procedures for determining the areas of chromatographic peaks including rectangular] template, triangulation] integration] faE,t and slow planimeters and OSCAR (467) have appeared. Instrumental peak distortion arising from post column effects such as relaxation time effects in the detector,
amplifier] and recording system was analyzed by McWilliam and Bolton (465). A newly developed double-peak (481) simulator in which the height and width of each peak and the degree of asymmetry may be varied a t will is useful in evaluating the influence of peak overlap on chromatographic accuracy. A catharometer detector was modified to provide a derivative signal and applied in the quantitative determination of poorly resolved components (332). The use of transparent plastic overlays which yield the concentration of components in a mixture with a minimum of calculations has been recommended (105). Devices used in the quantitative interpretation of GC data have been described and their relative performance has been discussed with the conclusion that digital computers appear to offer the greatest potential for extending interpretation capabilities (317, 419). The use of analog and digital computer methods for the determination of fatty acid esters was critically evaluated (96). A digital computer has been used in the unequivocal differentiation between Arabica and Robusta coffees on the basis of their GC profiles and may lead to a correlation between analytical data and organoleptic evaluations (4.9). Wade and Cram (704) treated Gaussian elution profiles as parabolas with floating base line techniques; the semilogarithmic chromatograms obtained keep all peaks on scale without manual attention, small peak areas are increased in relative size to allow area calculation, and the total number of peaks in complex samples can be determined. Use of a gas density balance in parallel with other detectors such as a thermal conductivity or flame ionization detector allows calibration of these detectors and rapid determination of specific correction factors (259). Correction factors for the quantitative evaluation of overlapping peaks were developed (552) which depend on only two parameters which are characteristic of peak separation and the peak area ratio. Molar responses (610) and weight responses (611) of fatty acid methyl esters were measured for the flame ionization detector and the @-ionization detector and used in correction factors for quantitative determinations. Flame ionization detector molar responses have also been measured (5) for methyl esters of polyfunctional metabolic acids and T C molar responses were evaluated for the Ca to C14 a-olefins (474).
Qualitative Studies and Interfacing Ancillary Techniques. Although the collection of retention data by numerous workers continues t o be of primary importance in qualitative analysis, emphasis once again during
ANALYTICAL CHEMISTRY, VOL. 42, NO. 5, APRIL 1970
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this biennium has been on combining GC with other techniques such as mass spectrometry, infrared spectroscopy, and other spectrochemical methods. The recent text on “Ancillary Techniques of Gas Chromatography” edited by Ettre and McFadden (186) includes chapters on GC-MS, GC-IR and Raman, GC-NMR, GC-TLC, pyrolysis GC, precolumn reactor techniques, and chemical identification techniques, among others. A general and operational review of the coupling of GC with mass spectrometry by Littlewood (414) cites 66 references and some applications. Karasek (335, 336) has described the principles and characteristics of molecular separators, a most important consideration for analyzing compounds with molecular weights to 1000 and samples down to 0.01 pg (576). Deactivation treatment for the WatsonBiemann separator eliminates loss of polar compounds (441). Mathematical models, developed to investigate the performance characteristics and design parameters of semipermeable membranes and silver-palladium separators, demonstrate that these devices should concentrate the sample by factors of 10 to more than 100 (428). Silver membrane molecular separators have been developed and applied (54, 56). Llewellyn (421, 422) described two-stage membrane-type separators which include a variable conductance device to control the sample throughput to the MS. The coupling of open tubular columns with a mass spectrometer using the Ryhage jet-type molecular separator was studied in some detail (495). Merritt et al. (469) used a capillary flow restrictor to reduce the inlet pressure to the ion source. The effect of dead volumes and most unswept volumes in the vacuum lines of the MS inlet system was investigated to determine the loss in resolution (409). The liquid phase bleed from an analytical column may be greatly reduced by adding a short adsorption column prior to the separator (407). The coupling of GC and MS has brought about a wide diversity of applications. These include the analysis of metal chelates, including rare earth chelates and double chelates of the alkali metals (442); clinical applications (293); and analysis of monosaccharides (287) and plant root constituents (216). Digital recording of low resolution, fast scanning MS was used by Hites and Biemann to test a computerized data acquisition system for GC-MS analyses (290). Data reduction routines for fast scan, high resolution spectra were reported with applications to the identification of natural steroids (100). Littlewood (416) and Wilks (720) reviewed the technological aspects and applications of coupling I R and GC. 12 R
1R analysis on trapped effluents has been applied in toxicology studies, and trapping efficiencies of greater than 70% are reported (140). Behrendt (36) proposed a microanalyzer to measure the effect of the sample vapor on I R radiation in order to solve the problem of small sample capacity of capillary columns. Scott and Wilkins (603) used stop-start chromatography in 5-ml gas cells without appreciable loss in resolution for I R and ;LIS analyses. Instrumentation was described (376) for a fast scan I R which takes 0.5 second per scan and makes continuous analysis and other applications possible (58). Trapping on short chromatographic columns with subsequent elution into spherical NMR microcells gave recoveries of nearly 100% (207), and magnetic resonance for gaseous comportents was shown to be rapid (1 to 2 seconds) and functional (195). Trapping of off-line spectroscopic methods of analysis were evaluated for use with open tubular columns (661). Cram and Brownlee (123) coupled gas chromatography and neutron activation analysis, with NaI (Tl) scintillation crystals, for the analysis of organic halides and short-lived isotopes. The response of the Geiger counter detector was characterized by Lubkowitz (427) for both a large and small volume detector, and a small volume flow proportional counter was used to measure the change in count rate due to changes in the detector gas composition (346). SPECIALIZED OPERATIONS
Preparative Scale. Several reviews on preparative scale gas chromatography have appeared during this biennium (295, 587, 696, 697). Prevot et al. (549) reported on the meeting on preparative GC held a t the Institut des Corps Gras in April 1968 and described the new preparative gas chromatograph, T H N-101, constructed by Compagnie Francaise Thomson Houston-Hotchkiss Brant, which is equipped with an electronic system enabling complete automatic control and regulation. A detailed description of the automatic preparative gas chromatograph APG 402 made by Dr. Hupe Apparatebau in Karlsruhe, Germany, has also appeared in the literature (294). A U. S. patent has been issued on an automatic preparative unit developed by Frazer (212). Work on production scale gas chromatography is continuing a t Abcor, Inc., a t which pilot units with 1-foot and 6-inch-diameter columns have been built (102), and the separation of certain mixtures is claimed to be imminent in 1- to 4-foot-diameter systems (674). Important aspects in large scale chromatography were outlined (665), and workers at the Continental Oil Co. reported in detail (88) on the
ANALYTICAL CHEMISTRY, VOL. 42, NO. 5, APRIL 1970
design of an apparatus which will accept columns up to 12 inches in diameter. A two-stage preparative unit which allows repeated analysis of certain peaks or groups of compounds with improved separation was described (44). Gradient-loaded columns with liquid loads varying from as high as 40% a t the inlet to 10% near the outlet have been recommended for preparative columns (173). The advantages of using columns of different diameter in tandem were also considered (709). A patent was issued (133) on the use of layers of relatively large diameter particles near each outlet of a multiple section column to promote transverse or lateral movement of the solute. Hupe et al. (296) studied variations in solute migration velocity owing to variations in packing density in a 10-cm-diameter column using conventional columnfilling techniques. The performance of preparative columns is claimed to be improved by temperature programming with column diameters less than 30 mm and a programming rate less than 4 to 5’ per minute (703). A patent was issued (158) for the use of a packing material in a preparative scale column containing elongated elements of glass or,metal which may be heated and which are spaced in the packing so that the distance between elements approximates the diameter of ordinary analytical columns. A simple device triggered by the emerging peak and independent of peak retention time was constructed (487) for the unsymmetrical cutting of preparative GC peaks. A peak slope sensing device for activation of an automatic fraction collector was also proposed (31) and developed for use with an Aerograph Autoprep. An electrostatic precipitation device also proved useful for trapping aerosols on this instrument (105). Witte and Dissinger (730) developed an interesting new quantitative approach for sample collection which involves adsorption of the pure eluted compound on a zone as small as 2 p1 in volume of microcrystalline organic material prepared by rapidly cooling a spectroscopic solvent with liquid nitrogen. A U. S. patent was issued (312) for a sample collection device containing a gas-permeable screen arranged in an annular elongated form and closed a t one end, thus allowing collection of fog-forming substances. A total collection system was described (22) in which organic eluents from a preparative scale unit were trapped in a closed system by absorbing the COZ carrier gas used for elution in base. Japanese workers (301) found improvement in trapping efficiency by connecting a heating tube between the column and the trap to increase the temperature gradient a t the trap. Applications of preparative scale GC
are numerous and only a few novel studies of general interest are reviewed here. Organic compounds containing exchangeable hydrogen atoms such as alcohols, phenols, carboxylic acids, acetylacetone, acetoacetic esters, diethyl malonate, ethyl cyanoacetate, nitromethane, acetone, acetophenone, cyclohexanone, chloroform, and acetonitrile may be deuterated by passage through a preparative column containing a polyhydroxy1 compound such as diglycerol labeled by periodic injection of deuterium oxide (309). High purity crystalline sterols were prepared (691) using the capillary tube collection technique, and 14 alkaloids in the phenylethylamine and tetrahydroisoquinoline groups present in peyote were separated and identified (432). Temperature and Flow Programming. Thorough reviews of the mathematical and physicochemical principles (482) and practices (673) of programmed temperature gas chromatography (PTGC) were published. Kaiser (327) described the current status of reversion GC and showed that volatile traces in gases can be detected down to a concentration of 5 X 10-loo/o with this technique. The advantages of graphitized carbon black columns for PTGC of complex mixtures were discussed (367). Equations were derived for calculation of a correlation isothermal index for PTGC, and a criterion for selection of optimum PTGC parameters was given which allows identification of substances in PTGC by application of isothermal retention data (239). Russian workers derived an equation for the retention time using nonlinear temperature programming and compared the predicted and experimental values for a series of normal paraffins (483). The same technique was used to measure heats of solution, and the values obtained were correlated with carbon number a t three different heating rates (701). The use of several independent heating units along the length of the column was found to give better separations and greater flexibility in PTGC (196). An inexpensive linear temperature programmer, using a capacitance operated relay for temperature control gives fluctuations of less than 1 "C from linearity (281). Goforth and Harris (235) developed techniques and apparatus for linear temperature programming of a column a t rates of up to 400 OC per minute. This method utilizes direct electrical heating of the columns which are 0.10 inch in i.d. with 0.012-inch wall thickness. Addition of a short column, with a very low volatility liquid phase, on the end of the partitioning column was shown to be applicable for work a t high sensitivities in PTGC and superior to the dual-column technique (408). Treatment of injection
port membranes to minimize thermal degradation during temperature programming extends the limit of sensitivity in PTGC (537). The efficiency of preparative (703) and capillary (596) columns under temperature programming was studied experimentally. Scott (601) discussed the design and theory of the simple flow programmer, the pressure programmer, program forms other than logarithmic, applications, and quantitative analysis by flow programming gas chromatography (FPGC). The theoretical aspects of GC with temperature programming followed by a flow program "ere considered (651), and appreciably faster separations were experimentally demonstrated on packed (654) and capillary (439, 440) columns. Theoretical models of Hartzog (278) describe the retention time and peak width of eluted components for both programmed temperature and programmed pressure GC. Equations relating retention pressure and retention time to the programming rate were developed by Kelley and Walker (350) and the time dependence of the column pressure was explicitly considered in their treatment of open tubular columns (349). Theoretical aspects of FPGC were presented in a series of articles by Mazor et al. (452, 453, 653), who also demonstrated the applicability of Kovats retention indices to FPGC (451). The best program is obtained when isobaric and stepwise programs are combined (454). Devices for automatic exponential programming of the inlet pressure (264) which offer preselection of the pressure range (604) with a reproducibility of f1% (266) are described. Deininger and Halasz (150) introduced a pneumatic control device before the column and a mixing and splitting chamber between the column and the detector. Under these conditions, the calibration factors for quantitative analysis and the noise and drift of the flame ionization detector were independent of the column flow rate. Quantitative analyses were also discussed by Vergnaud (694). The advantages of stepwise discontinuous programming (457) and programming combining continuous and stepwise programming (455) were demonstrated. Pyrolysis. Several reviews on the general topic of pyrolysis have appeared (18, 125, 400, 530). Stack (624, 615) reviewed the pyrolysis-gas chromatography of biological macromolecules and concluded that in some cases proteins can be identified and differentiated by pyrolysis at low temperatures and that simple mixtures of carbohydrate and protein can sometimes be identified. The limitations of extending pyrolysisG C to quantitative analysis of copolymers were outlined by Jones (320). Optimum temperatures for pyrolysis
were measured for a variety of compounds and were generally found to be in the range 600 to 650 "C (641). Temperature rise times for both filament and induction heating pyrolysis units were measured by Levy and Fanter (406) by a method based on monitoring the emission of light with a multiplier phototube. Patents were issued on a two-column pyrolysis-GC system which pyrolyzes samples as they are eluted from the first column and separates the pyrolysis products on a second column (402); on a reaction chamber and sample introduction system which allows pyrolysis of a sample in an ampoule and provides a means of breaking the ampoule, allowing the volatile components to be flushed into the chromatograph (557); and on a system in which components of a sample eluted from one chromatographic column are separately stored in a storage zone and individually passed to a pyrolyzer and then to a second chromatographic column (197). A pulsed ruby laser (206) and a high voltage electrical discharge tube (656) were used as alternate means to pyrolysis of bringing about degradation. Sonntag (630) described construction details for a universal prereactor system for pyrolysis which can be operated under a variety of conditions, and he studied the various pyrolysis GC techniques most commonly used on polymers-filament, ampoule, rapid heating, pyrolysis with and without carrier gas stream, bypass, step-pyrolysis, and dry distillation (628, 629). Several papers have dealt with pyrolysis of samples in the vapor phase (532, 659), and a wallless gas phase reactor (659) was found to give higher precision in first-order pyrolysis reactions then is generally observed in gas phase kinetics. A very important observation was reported by Farre-Rius and Guiochon (194), who showed that in most cases pyrolysis is completed a t a temperature well below the equilibrium temperature of the filament, furnace, or even induction heating unit used, and thus the rate of heating is of far greater importance to the nature of the pyrolysis products than the more commonly reported maximum temperature of the pyrolyzing element. Problems associated with hot filament-type and heated furnacetype pyrolyzers were reviewed (680), and it was recommended that the heat capacity of the sample holders used in some commercially available pyrolysis units be drastically reduced and very thin samples used. A tandem gas chromatographic system employing interrupted elution of components and a flow-through pyrolyzer was employed for hydrocarbons, fatty acid methyl esters, and alcohols (710, 731). The applications of pyrolysis-GC are too numerous to mention here, but
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a few particularly novel applications of general interest include the rapid classification of various species and strains of mycobacteria by pyrolysis of lyophilized bacterial cells (558,559),the rapid diagnosis of viral and fungal diseases in plants (484), a pyrolysis-gas chromatography-mass spectrometry candidate experiment for the biological exploration of Mars (618), a preliminary examination of Lunar samples from Apollo 11 for organic material (600), the determination of nonvolatile organic compounds in aqueous solutions and natural waters using steam as carrier gas (434, 436, 489), and the identification of synthetic fibers (299). The toxic pyrolysis products of polytetrafluoroethylene have been identified (113, 381, 715). Downing and Greene (163) showed that saturated fatty acids are quantitatively converted into their methyl esters when the dry tetramethylammonium salts of these acids are pyrolyzed in a specially constructed injection port. Conversion of tetrabutylammonium salts to the butyl esters by pyrolysis was also reported (599), as was transformation of quaternary ammonium compounds into their volatile dimethyl amino derivatives by pyrolysis on a flash-heating ribbon (646). The distribution of chlorine atoms in chlorinated poly(viny1 chlorides) was studied for partially chlorinated polymers by pyrolysis-GC (681). Reaction GC. Reaction gas chromatography involves the use of reactors in a chromatographic system to bring about specific chemical transformations of the components being analyzed, allowing, for example, qualitative identification of functional groups from changes in retention of components in the presence or absence of the reactor or change in retention to improve separation and analysis of the components of a mixture. An excellent monograph on reaction GC by Berezkin ( 4 1 ) has been translated into English and has particularly good coverage of work appearing prior to 1966. Reviews were also published by Littlewood (416) and Ettre (185). A compact microreactor system useful for a number of reactions including esterifications, saponifications, reductions, halogenations, pyrolysis, and ozonolysis was developed (53). Microozonolysis may be used for locating sites of unsaturation in olefinic acids (361, 666). Dehydrogenation converted alcohols to carbonyl compounds (363) and other products (513, 514) and hydrogenation was used to determine the carbon skeletons of microgram amounts of steroids and sterols ( 6 ) , to eliminate heteroatoms from solid samples (663), and to bring about complete conversion of unsaturated fatty acids to the saturated homologs (172). A precolumn of KOH and NaOH on 80/100-mesh Gas Chrom Q was used in pesticide resi14R
due analysis (473) and was shown to destroy some pesticides, change the retention time of others, and leave certain ones unaltered. Alkali fusion has also been applied to the analysis of alkyl sulfonates (486). Compounds separated gas chromatographically may be characterized by their oxygen consumption during catalytic oxidation, in which case the change in oxygen content of the carrier gas is monitored (362). Organophosphorus pesticides were characterized by irradiation with ultraviolet light and GC separation of the decomposition products (475). Reaction GC has been used by several authors for elemental analysis. The C/H ratio of organic materials eluted from a chromatographic column may be determined continuously (208). Other authors have also developed techniques for carbon and hydrogen (43); carbon, hydrogen, and nitrogen using a NiO catalyst a t 1000°C (108); carbon, nitrogen, sulfur, and oxygen (170), and carbon in phosphorus (45). An accuracy of 0.03 to 0.05% for 1 to 2 mg samples has been claimed (107) for the determination of hydrogen in organic substances by a combined GCcoulometric procedure. Kojima and coworkers (371) developed a selective method for oxygen-containing compounds in amounts as low as 10-'0 mole in the presence of large amounts of non-oxygen-containing compounds. A Kjeldahl digestion combined with reaction GC was applied to the determination of nitrogen in organic substances in the range 0.1 to 0.005% (209), and the selective detection of nitrogen, halogen, and sulfur compounds by combining reaction GC with several selective detectors was reported (215). MISCELLANEOUS
Interesting developments of a unique nature published during this biennium include pulsed gas chromatography in which no carrier gas is employed, since a vacuum is used as the driving force (203); the differential chromatographic technique of Zhukhovitsky (738),which also does not employ a carrier gas; the high pressure gas chromatographic elution of macromolecules (230); and the use of sieved conductive rubber from a standard anesthesia breathing tube as the column packing (666). Negative results were again observed in an attempted separation of racemates on a column of optically active quartz (10). Metallic Compounds. Publications on the separation of metallic compounds continue to increase, and we are again devoting a separate section in this review to the subject. Sokolov and coworkers (631) describe an instrument for the separation of metal vapors at temperatures up to 1000 "C and demonstrate its value in the separa-
ANALYTICAL CHEMISTRY, VOL. 42, NO. 5, APRIL 1970
tion of Cd and Zn mixtures a t 850 "Con a column packed with diatomite firebrick. Silicon in nickel, copper, and aluminum alloys was determined by destruction of the alloys with gaseous chlorine at 600 to 900 "C and elution of the SiC14 formed using a Kel F-40 polymer wax column a t 75 "C (614). The retention properties of TiCl4, SnCl,, GeC14, SbCL, AsCL, SiC14, POcl,, PCh, VOC13, Sn(CH3)4, Ge(CH3)C13, and Sn(CH&Cl were studied systematically on a number of organic liquid phases and on aluminum bromide (72). The germanium present in coal was determined by conversion to GeC14, concentrating in an activated carbon trap, and eluting from a petroleum grease-Celite column (588). Trace amounts of chlorinated organic compounds may be separated from GeC14 by elution from a column of modified silica gel ( 7 ) . Juvet, Shaw, and Kahn (325) separated NbCls and TaClS on a column containing LihlCl4 as liquid phase and showed that equilibrium constants for the complex equilibria in inorganic fused salt systems may be accurately measured for both volatile and nonvolatile systems in tetrachloroaluminate and tetrachloroferrate melts. Rare earth chlorides were eluted as the volatile complexes of A1Ch a t 5 2 5 0 "C using aluminum chloride vapors (40 to 170 torr) as a component of the carrier gas (742). Considerations in the design of an apparatus for the analysis of volatile corrosive metal fluorides were reviewed by Pitak (539), who found an electron-capture detector constructed of suitable materials and capillary columns suitable for the analysis of metal fluorides. The elution of XeFz was reported using a column containing 15% Kel F-10 on Fluoropak 80 (735). Considerable research has appeared on the separation of volatile metal chelates, particularly the chelates of chrominum, beryllium, and aluminum. The trifluoroacetylacetonate of chromium has been used in the determination of chromium in serum (583),urine (584), and ferrous alloys (569). Veening and Huber (693) found that retention of the fluoroacetylacetonates of chromium and ruthenium is greatly influenced by adsorption a t low liquid loads, even when silanized supports are used. Traces of aluminum as small as 0.1 ppm in uranyl nitrate solutions were determined following extraction as the trifluoroacetylacetonate with benzene (224). The GC determinations of beryllium in biological materials has been reported (600) and the limit of detection given by Ross and Sievers (570) as 4 X lo-', gram using an electron-capture detector. Other volatile metal chelates studied during this biennium include the benzoyltrifluoroace-
tonates and the thenoyltrifluoroacetonates of copper, aluminum, gallium, chromium, and iron (83);the tris(2,2,6,6,-tetramethylheptanedionato) chelate of ytterbium(II1) (225); the chloro-ophenylenediamine chelates of selenium (486); and the bis(trifluoroacetylpiva1oylmethano) chelates of copper (657) and the tripositive rare earths (656). Other workers have also eluted the trispivaloyltrifluoroacetonates of the rare earths (612). Motley and Meloan (480) evaluated the number of water molecules associated with the uranyl-8quinolinol chelate when extracted from water into 1-decanol and nitromethane, and Juvet and Pesek (324) showed that structures of nonvolatile metal chelates can be determined gas chromatographically by employing various mixtures of a metal hydroxide and a chelating ligand as the liquid phase and following the changes in retention of inert solutes as a function of liquid phase metal composition. The chromatography of a variety of metal alkyls was also studied during this biennial. Organometallic compounds of mercury (490, 491), tin (315, 607, 682), and lead (86, 92, 632) are among those investigated. Cantuti and Cartoni (86) found that atmospheric tetraethyllead may be measured rapidly and accurately a t the 0.1 to 0.4 ppm level by gas chromatography. The monobrominated isomers of dimethylphenyl-amine, -phosphine, and -arsine were separated (572) using a number of column materials, but a Carbowax-2-nitroterephthalic acid column was most suitable for the arsines and the phosphines. Nickel carbonyl (638) and a series of arene tricarbonyl chromium complexes (692) have been eluted. Several metalloporphyrins (337) were also separated in an interesting investigation using an epoxy resin (Epon 1001) as the liquid phase and dichlorodifluoromethane as the solvent gas a t pressures up to 3100 psi and temperatures of 140 to 170 "C. The GC behavior of silicon, germanium, titanium, zirconium, hafnium, and aluminum isopropoxides and titanium, zirconium, and hafnium tertiary amyloxides has been reported (76). The GC separation of metal-olefin complexes reported this biennium include thallium(1) as the cyclopentadiene derivative (60) and iron in the form of ferrocene and its derivatives (542). Alkyl silicates used in heat transfer fluids in aircraft can be separated and identified (660) Volatile silylated derivatives of sulfo- and selenoamino acids were prepared using bis(trimethy1silyl) acetamide (85). Eleven different liquid phases were evaluated for the temperature-programmed separation of mixtures of chlorosilanes, methylchlorosilanes, and associated siloxanes (81). Mixtures of silylated derivatives in the I
presence of nonsilylated species may be selectively detected by a siliconspecific detector based on interfacing a gas chromatograph and a flame emission or atomic absorption spectrometer (479). Finally, the kinetics of the reduction of iron oxides was investigated by eluting a sample of hydrogen gas from a column packed with iron oxide (556). The activation energy and other kinetic data were determined for the decomposition of CaC08 a t 750, 777, and 800 OC and preliminary studies were made on the decomposition of Cas04 gas chromatographically (488). The oxygen in various oxides of vanadium was quantitatively determined by fusing the sample a t 2400 "C in a graphite crucible for 6 minutes and measuring the CO evolved (393). Further studies on the quantitative evaluation of gases in metals using a carbon arc technique were outlined by Winge and Fassel (729), and an evolved-gas technique for inorganic solids and thin films was illustrated by determining moisture in CuSO4 5Hz0and in mineralogical AlzOs 3Hz0samples (160). Thermogravimetry and gas chromatography were used simultaneously in the study of the thermal decomposition of calcium oxalate and of phosphate-containing minerals (55). Reagents capable of oxidizing iodide to Izmay be determined (529) by gas chromatographic measurement of the Iz formed. Silica may be determined by reaction with ammonium bifluoride and acid to form silicon tetrafluoride (687) and metallic magnesium (or other active metals) by measurement of the hydrogen liberated upon addition of acid (292). Physical-Analytical Measurements. Conder (114) and Trestianu (676, 677) reviewed a number of physicalanalytical measurements conveniently made by gas chromatography, including activity coefficients, vapor pressures, enthalpies, kinetic constants, interdiffusion coefficients, adsorption isotherms and isosteres, surface areas, boiling points, complex equilibria, and second virial coefficients of gas mixtures. Surface areas were measured for small metallic areas of bulk specimens using methane as the adsorbate (662) and for cellulose and its esters (192). A FORTRAN I1 program for use with the IBM 7090 computer for surface area measurements was reported (213). Adsorption isotherms were determined for water, acetone, and benzene on modified glass surfaces (204); acetone on liquid-coated diatomaceous earth supports (683, 684); benzene and hexane mixtures on silica gel (609); and water and methanol on several types of polyamide textile fibers ( i 7 9 ) . Activity coefficients are reported for C4 to Cs hydrocarbons in higher molecular weight hydrocarbons (li8,137,288,734) and in binary mixtures of hydrocarbons (623);
-
+
C&I hydrocarbons in binary mixtures of P,B'-oxydipropionitrile and dibutyl maleate (560); paraffins, aromatics, and halogenated aromatics in Carbowax 400 ( 5 2 ) ; and fluorinated benzenes in noctadecane in a rigorous study (136). The evaluation of relative activity coefficients and their use in calculating retention indices was applied to aliphatic alcohols with a number of liquid phases (61). Conder and Purnell (115) presented a theoretical approach for calculation of activity coefficients a t finite solute concentrations and evaluated the effect of gas imperfections on calculated values through the second virial coefficient. A number of other workers have determined second virial coefficients by means of gas chromatographic measurements (135, 143, 191, 217, 528). Franck evaluated a gas chromatographic method for the direct determination of vapor pressures (210). Four GC methods-frontal analysis, frontal analysis by characteristic point, elution by characteristic point, and elution on a plateau-were employed for thermodynamic measurements in in binary gas-liquid and gas-solid systems a t finite solute concentrations (117). The value of gas chromatography in measuring thermodynamic quantities is now well established and the technique has been used in heat of solution measurements (325, 591), heat of mixing of hexafluorobenzene with amines ( l a ) , absolute entropies ( 7 2 l ) , and heats of adsorption (98, 157, 305, 450,586). Martire and coworkers (447) confirmed the value of GC for measurement of the thermodynamic quantities and molecular properties of liquid crystals. Solution complex equilibrium constants were measured for silver complexes of nitriles (694), complexes formed between benzene, toluene, and xylenes with di-n-propyl tetrachlorophthalate (84), and complexes in inorganic fused salt systems (385). GC methods for the investigation of the kinetics of liquid phase reactions have been reviewed (42) and the unimolecular dissociation of dicyclopentadiene has been determined by a gas chromatographic chemical reactor (547). The rate of chemisorption of hydrogen on a nickel catalyst was measured by Padberg and Smith (615) and a GC method used to measure the activation energy for first-order reactions (593). Finally, a few novel applications of a general nature, including the determination of the lipid and fatty acid composition of earthworms (Lumbricus terrestris) (97), the composition of bovine muscle lipids a t various carcass locations (508), and the identity of the odorous substance produced by Streptomyces griseoluteus (568), are an indication of the great versatility of gas chromatography.
ANALYTICAL CHEMISTRY, VOL. 42, NO. 5, APRIL 1970
15R
LITERATURE CITED
(1) Abernethy, R. F., and Walters, J. G., ANAL.CHEM.,41[5], 308R (1969). (2) Ackman, R. G., J . Gas Chromatog. 6, 497 (1968). (3) Ackman, R. G., and Hooper, S. N., J . Chromatog. Sci., 7,549 (1969). (4) Ackman, R. G., Kates, M., and Hansen, R. P., Biochim. Biophys. Acta, 176,673 (1969). (5) Addison, R. F., and Ackman, R. G., J . Gas Chromatog., 6,135 (1968). (6) Adhikary, P. M., and Harkness, R. A,, ANAL.CHEM.,41, 470 (1969). 17’) Aeliulov. N. Kh.. Feshchenko. I. A.. ando Deviatykh, G. G., Zh. ’Analit: Khim., 23, 575 (1968). (8) Al’tshuler, 0. V., Vinogradova, 0. M., and Tsitovskava, Tsitovskaya, I. L., Zavodsk. Lab., 32,1210 32, 1210 (1966j. (1966). ’ 19) I , Altshuller. A. P.. ANAL. CHEM..41 [ 5 ] , 1R (1969). (10) Amariglio, A,, Compt. Rend. Ser. C, 268, 1981 (1969). (11) Arkenbout, G. J., and Smith, W. hf., Separation Sci., 2, 575 (1967). 112) Armitaee. D. A.. and Morcom. K. W..’ ‘ Trans. FaGday Soh., 65,688 (1969). (13) Armitage, F., J . Chromatog. Sci., 7, 190 (1969). (14) Arnikar, H. J., Rao, T. S., and Karmarkar, K. H., Indian J . Chem., 5,480 (1967). (15) Arnikar, H. J., Rao, T. S., and Karmarkar. K. H.. Intern. J . Electronics, 22, ’381 (1967). (16) Arnikar, H. J., Rao, T. S., and Karmarkar, K. H., J . Chromatog., 38, 126 (1968). (17) Ashley, J. W., Dissertation Abstr., 27, 3804 (1967). (18) Audebert, R., Ann. Chim., 3, 49 (1968). (19) Bache, C. A., and Lisk, D. J., ANAL.CHEM.,39, 786 (1967). (20) Bache, C. A., and Lisk, D. J., “Biomedical Applications of Gas Chromatography,” Vol. 2, pp. 165-78, H. A. Szymanski, ed., Plenum Press, New York, 1968. (21) Bache, C. A., and Lisk, D. J., J . Assoc. Anal. Chemists, 50, 1246 (1967). (22) Bache, C. A,, and Lisk, D. J., J . Chromatog. Sci., 7, 296 (1969). (23) Bache, C. A,, and Lisk, D. J., J . Gas Chromatog., 6,301 (1968). (24) Ball, D. L., Harris, W. E., and Habgood, H. W., ANAL. CHEM.,40, 129 (1968). (25) Zbid., p. 1113. (26) Ballinger, J. T., Bartels, T. T., and Taylor, J. H., J . Gas Chromatog., 6, 295 (1968). (27) Banthorpe, D. V., Gatford, C., and Hollebone, B. R., Zbid., 6, 61 (1968). (28) Barakat, M. F., J . Sci. Znstr., 44, 1031 (1967). (29) Bardyshev, I. I., Kulikov, V. I., Naumovich, L. A., and Tumysheva, T. V., Zh. Anal. Khim., 23, 1893 (1968). (30) Bartel, E. E., and van der Walt, S . J., J . Gas Chromatog., 6, 396 (1968). (31) Bartlet, J. C., Zbid., 6, 183 (1968). (32) Baumann, F., Erdol Kohle, 21, 635 (1968). (33) Baumann, F., and Tao, F., J . Gas Chromatog., 5,621 (1967). (34) Beckman, H., and Gauer, W. O., Bull. Environ. Contam. Toxicol., 1, 149 (1966). (35) Beeson, J. H., and Pecsar, R. E., ANAL.CHEM.,41, 1678 (1969). (36) Behrendt, S., J . Gas Chromatog., 6, 226 (1968). (37) Belenky, B. G., Orestova, V. A., and Firsova, V. K., Zh. Anal. Khim., 23, 1834 (1968). \
,
L.1,
16R
~~
\ - - - - ,
(38) Beljakova, L. D., Kiselev, A. V., and Kovalena, N. V., Bull. SOC.Chim. France, 1967, 285. (39) Bellet, E. M., Westlake, W. E., and Gunther, F. A,, Bull. Environ. Contam. Tosicol., 2, 255 (1967). (40) Bentsen, P. C., and Bethea, R. M., J . Chromatog. Sci., 7,399 (1969). (41) Berezkin, V. G., “Analytical Reaction Gas Chromatography,” Plenum Press, New York, 1968. (42) Berezkin, V. G., Usp. Khim., 37, 1348 (1968). (43) Berezkin, V. G., Luskina, B. M., Syavtsillo, S. V., and Terentiev, A. P., Zh. Analit. Khim., 23, 1254 (1968). 144) Berezkin. V. G.. and Rastvannikov. ’ Ye., G., Zz;. Akad. Nauk SQSR, Ser: Khim., 1968, 240. (45) Berezkina, L. G., and Elefterova, N. A., Zh. Analit. Khim. 24, 269 (1969): (46) Berman. A. D.. Frank. Y. A,. and ‘ Yanovskii,’ hf. I.,’ Zavoddk. Lab.’, 34, 272 (1968). (47) Bevenue, A., and Ogata, J. N., J . Chromatog. 35, 17 (1968). (48) Bierl, B. A., Beroza, hi., and Ruth, J. hl.. J . Gas Chromatoa.. 6.286 (19681. (49) Biggers, R. E., Hhdn, J . ~J., and Gianturco, M. A., J . Chromatog. Sci., 7,453 (1969). (50) Bighi, C., Betti, A., and Dondi, F., J . Chromatog., 39, 125 (1969). (51) Bighi, C., Betti, A., Saglietto, G., and Dondi, F., Zbid., 34, 389 (1968). (52) Zbid., 35, 309 (1968). (53) Bitner, E. D., Davison, V. L., and Dutton, H. J., J . Am. Oil Chemists Soc., 46, 113 (1969). (54) Black, D. R., Flath, R. A., and Teranishi, R., J. Chromatog. Sci. 7, 284 11969). \ - - - - ,
(55) Blandenet, G., Chromatographia, 2, 184 (1969). (56) Blumer,. M .., ANAL. CHEM., . 40,. 1590 (1968). (57) Bobbitt, J. M., Schwarting, .A. E., and Gritter. R. J.. “Introduction to Chi Yo1 (58)
Chem., 238,
(59) BochinsE
Pat.ent 3.378.725 ( A m . 1968). (60) Bock,’ R.; and ‘Monerjan, A., Z. Anal. Chem., 235,317 (1968). (61) Bonastre, J., and Grenier, P., Bull. SOC.Chim. France, 1968, 118. (62) Zbid., p. 1292. (63) Bonastre, J., Grenier, P., and Cazenave, P., Zbid., 1968, 388.5. (64) Bouche, J., and Verzele, M., J . Gas Chromatog., 6, 501 (1968). (65) Bowman, h f . C., and Beroza, M., ANAL.CHEM.,40, 535 (1968). (66) Zbid., p 1448. (67) Bowman, 11.C., and Beroza, M., J . Agr. Food Chem., 15, 651 (1967). (68) Bowman, M. C., and Beroza, hl., J . Assoc. O j i c . Anal. Chemists, 50, 1228 (1967). (69) Bowman, M. C., and Beroza, M., J . Chromatog. Sci., 7,484 (1969). (70) Braman, R. S., and Dynako, A., ANAL.CHEM.,40, 95 (1968). (71) Brazhnikov, V., and Moseva, L., and Sakodvnski. K.. J . Chromatoa.. ” , 38., 287 (1‘968); ‘ ’ (72) Brazhnikov, V., and Sakodynsk, S., Zbid., 38, 244 (1968). (73) Brookman, D. J., and Sawyer, D. T., ANAL.CHEM.,40, 106 (1968). (74) Ibid., p. 1368. (75) Zbid., p. 2013. (76) Brown, L. M., and Mazdiyasni, K. S., Zbid., 41, 1243 (1969). (77) Brunnock, J. V., and Luke, L. A., J . Chromatog., 39, 502 (1969).
ANALYTICAL CHEMISTRY, VOL. 42, NO. 5, APRIL 1970
(78) Buchanan, J. E., and Maher, T. P., J . Gas Chromatog., 6,474 (1968). (79) Buhl, D., ANAL. CHEM., 40, 715 (1968). (80) Burriel-Marti, F., Condal-Bosch, L., and Gassiot-Matas, M., Chromatogra hia, 1, 507 (1968). (81) urson, K. R., and Kenner, C. T., ANAL.CHEM.,41, 870 (1969). (82) Burson, K. R., and Kenner, C. T., J . Chromatog. Sci., 7, 63 (1969). (83) Butts, W. C., Dissertation Abstr., 29, 506-B (1968). (84) Cadogan, D. F., and Purnell, J. H., J . Chem. SOC.,Ser. A., 1968,2133. (85) Caldwell, K. A., and Tappel, A. L., J . Chromatog., 32, 635 (1968). (86) Cantuti, V., and Cartoni, G. P., Zbid., 32, 641 (1968). (87) .Carel, A. B., Anal. Chim. Acta, 41, 510 (1968). (88) Carel, A. B., Clement, R. E., and Perkins, G., J . Chromatog. Sci., 7, 218 (1969’). (89jCarmichae1, J. B., Separation Sci., 3,249 (1968). (90) Carter, D. H., J . Gas Chromatog., 5. 612 (1967). (91) Cartoni, G. P., and Possanzini, hf., J . Chromatog., 39, 99 (1969). (92) Castello, G., Chim. Ind. (Milan), 51,700 (1969). (93) Castello, G., and D’Amato, G., J . Chromatog., 32, 625 (1968). (94) Castello, G., and Munari, S., Chim. Znd. (Milan),.51, 469 (1969). (95) Castellucci, N. T., and Eisaman, P. R., J. Gas Chromatqg., 6,599 (1968). (96). Caste!, W. O., in “Methods of Biochemical Analysis,’> David Glick, ed., pp. 135-88, Interscience, 1969. (97). Cerbulis, J., and Taylor, hf. W., Lzpzds, 4, 363 (1969). (98) Chabert, B., and Edel, G., Compt. Rend. Ser. C, 267, 54 (1968). (99) Chang, T. C. L., J . Chromatog., 37, 14 (1968). (100) Chapman, J. R., Barber, M., Wolstenholme, W. A., and Bailey, E., in “Gas Chromatography, 1968,” pp. 252-9, C. L. A. Harbourn and R. Stock, eds., Elsevier, New York, 196Qil (101) Chapman, R. L., ed., Environmental Pollution Instrumentation,” Instrument Society of America, Pittsburgh, Pa., 1969. (102) Chem. Eng. News, 46 [14], 62 11968). (103j-%d., 47 [29], 102 (1969). (104) Chen, K. A,, ANAL. CHEM.,40, 1171 (1968). (105) Chin, A. L., and Luberoff, B. J., J . Gas Chromatoa.. 6.525 (1968). (106) Chromatogrdphiu, 2, 11 (1969). (107) Chumachenko, M. N., and Levina, N. B., Zh. Analit. Khim., 23, 1250 (1968). (108) Chumachenko, M. ?I and ., Pakhomova, I. Ye., Zzv. Akad. Nauk SSSR, Ser. Khim., 1968,235. (109) Claeys, R. R., and Freund, H., J . Gas Chromatog., 6,421 (1968). (110) Clardy, E. K., U. S. Patent 3,443,415 (May 13,1969). (111) Coahran, D. R., Bull. Environ. Contam. Toxicol., 1, 141 (1966). (112) Cockle, N. A,, and Tiley, P. F., Chem. Ind. (London),1968,1118. (113) Coleman, W., Scheel, L., and Gorski, C.. Am. Znd. Hua. 111. “ - Assoc. J.., 29 . .. 54 (1968). (114) Conder, J. R., in “Progress in Gas Chromatography,” pp. 209-70, J. H. Purnell, ed., Interscience, New York, \ - - - - ,
1968.
(1?5)Conder, J. R., and Purnell, J. H., Trans. Faraday SOC.,64,1505 (1968). (116) Ibid., p. 3100. (117) Zbid., 65,824 (1969). (118) Zbid., p. 839.
(119) Condon, R. D., and Ettre, L. S., L‘Instrumentation in Gas Chromatography,” Krugers, ed., pp. 87-109, Centrex, Eindhoven, 1968. (120) Conlan, D. A,, and Szonntagh, E. L., J . Gas Chromatog., 6,485 (1968). (121) Cook, R. F., Stanovick, R. P., and Cassil, C. C., J . Agr. Food Chem., 17, 277 (1969). (122) Coulson, D. M., Am. Lab., 1969,22. (123) Cram, S. P., and Brownlee, J. L., J . Gas Chromatog., 6,313 (1968). (124) Cramers, C. A. M. G., “Some Problems Encountered in High Resolution Gas Chromatography,” Technische Hogeschool, Eindhoven, 1967. (125) Cramers, C. A. M. G., and Keulemans, A. I. M., in “Instrumentation in Gas Chromatography,” J. Krugers, ed., pp. 71-85, Centrex, Eindhoven, 1968. (126) Cramers, C. A. M. G., and van Kessel, AI. Rf., J . Gas Chromatog., 6 , 577 (1962) \----/.
(127) Creitz, E. C., J . Chromatog. Sci., 7, 137 (1969). 1128) Creitz. E. C.. J . Res. Natl. Bur. Std.. ’ 72C, 187 (1968). ’ (129) Cremer, E., Gruber, H. C., and Huck, H., Chromatographia, 2, 197 (1969). (130) Crider, W. L., and Slater, R. W., AXAL.CHEM.41,531 (1969). (131) Cross, L. H., Inglefield, S., and Ward, N., U. S. Patent 3,376,731 (April 9, 1968). (132) Crowley, R. P. (to Abcor, Inc.) Ibid., 3,407,573 (Oct. 29, 1968). (133) Ibid., 3,436,897 (April 8, 1969). (134) Crowne, C. W. P., Gross, J. h!., Harper, hl., and Farrell, P. G., in “Fifth International Symposium on Chromatography and Electrophoresis, Brussels, 1968,” pp. 153-8, Ann ArborHumphrey Science Publishers, Ann Arbor, hIich., 1969. (135) Cruickshank, A. J. B., Gainey, B. W., Hicks, C. P., Letcher, T. M., Moody, R. W., and Young, C. L., Trans. Faraday SOC.,65, 1014 (1969). (136) Cruickshank, A. J. B., .Gainey, B. W., and Young, C. L., in “Gas Chromatography, 1968,” C. L. A. Harbourn and R. Stock, eds., pp. 76-89, Elsevier, New York, 1968. (137) Cruickshank, A. J. B., Gainey, B. W., and Young, C. L., Trans. Faraday Soc., 64,337 (1968). (138) Cruickshank, A. J. B., Windsor, hI. L., and Young, C. L., Proc. Roy. SOC.295A, 271 (1966). (139) Curry, A. S., Read, J. F., Brown, C., and Jenkins, R., “Fifth International Sxmpo&m on Chromatog. and Electrop oresis, Brussels, 1968,” pp. 91-4, Ann Arbor-Humphrey Science Publ., Ann Arbor, 1969. (140) Curry, A: S., Read, J. F., Brown, C., and Jenkins, R. W., J . Chromatog., 38,200 (1968). (141) Dalgliesh, C. E., C’hem. Brit., 4, 363 (1968). (142) Dal Nogare, S., and Juvet, R. S., “Gazo-Zhidkostnaya Khromatografiya,” Nedra, Leningrad, 1966. (143) Dantzler, E. hl., Knobler, C. M., and Windsor, hI. L., J . Chromatog., 32, 433 (1968). (144) d’Aubigne, J. N., Jacques, M,, and Guiochon, G., Chromatographia, 2, 98 (1969). (145) Davenport, T. B., Lab. Practice, 18, 306 (1969). (146) Davison, V. L., and Moore, D. J., J . Gas Chromatog., 6,540 (1968). (147) Deans, D. R., Chromatographia, 1, 187 (1968). (148) Ibid., p. 191. (149) de Bruyn, A,, Znd. Chim. Belge, 33, 155 (1968).
(150) Deininger, G., and Halasz, I., 2. Anal. Chem., 229, 14 (1967). (151) DeLigny, C. L., J . Chromatog., 36, 50 (1968). (152) DeLoach, H. K., Hemphill, D. D., J . Assoc. Ofic. Anal. Chemasts, 52, 533 (1969). (153) DeOliveira, D. B., J . Gas Chromatog. 6,230 (1968). (154) Devaux, P., and Guiochon, G., Chromatographia, 2,151 (1969). (155) Devaux, P., and Guiochon, G., J . Chromatog., 7,561 (1969). (156) Dimick, K. P., and Hartmann, C. H., U. S. Patent 3,423,181 (Jan. 21, 1969). (157) Dimitrov, Chr., Topalova, I., Bezouhanova, Ts., and Petsev, N., Compt. Rend. Acad. Bulgare Sci., 22, 559 (1969). (158) Dixmier, M. B., Roz, B., and Guiochon, G. (to Campagnie Francaise Thomson Houston-Hotchkiss Brandt), U. S. Patent 3,385,035 (May 28,1968). (159) Djavadov, S. P., Kiselev, A. V., and Nikitin, Y. S., Neftekhimiya, 8, 637 (1968). (160) Dorsey, G. A., Jr., ANAL.CHEM.,41, 350 (1969). (161) Douglas. A. G.. J . Chromatoa. Sci.. I
- - ~ \
(162) Douglas, D. M., and Schaefer, B. A., Zbid., 7,433 (1969). (163) Downing, D. T., and Greene, R. S., ANAL.CHEM40,827 (1968). (164) Dressler, M.,’and Janak, J., Collection Czech. Chem. Commun., 33, 3960 (1968). (16.5’1Ihid.. D. 3970. --(166) Zbid., 34,1797 (1969). (167) Dressler, M., and Janak, J., J . Chromatog. Sci., 7,451 (1969). (168) Drushel. H. V., ANAL.CHEM., . 41,. ‘ 569 (1969). ‘ (169) Dubsky, H., and Krejci, hf., Chem. Listy, 61, 1649 (1967). (170) Dugan, G., and Aluise, V. A., ANAL. CHEM.41,495 (1969). (171) Duggan, R. E., Barry, H. C., and Johnson, L. Y., Pesticide Monit. J., 1, 2 (1967). (172) Dutton, H. J., J . Am. Oil Chemists’ SOC.,45 [ 1],4A(1968). (173) Duty, R. C., J . Gas Chromatog. 6 , 193 (1968). (174) Dyson, N., and Littlewood, A. B., Zbid., 6,449 (1968). (175) Eberly, P. E., Znd. Eng. Chem. Fundamentals, 8,25 (1969). (176) Ebing, W., Chromatographia, 1, 382 (1968). (177) Ebing, W., J . Gas Chromatog., 6 , 79 (1968). (178) Ecknig, W., Rotzsche, H., and Kriegsmann, H., J . Chromatog., 38, 332 (1968). (179) Edel, G., and Chabert, B., Compt. Rend. Ser. C., 268,226 (1969). (180) Eden, C., and hlargoninski, Y., J . Gas Chromatog., 6,349 (1968). (181) Eggertsen, F. T., Seibert, E. E., and Stross, F. H., ANAL.CHEM.,41, 1175 I lR6R ). (182) Eik-Nes, K. B., and Homing, E. C., eds., “Gas-Phase Chromatography of Steroids,” Springer-Verlag, New York, 1968). (183) Engely, L., Levart, E., Guiochon, G., and Peslerbe, G., ANAL. CHEM.,41, 1446 (1969). (184) Ettre, L. S., J . Gas Chromatog., 6 , 404 (1968). (185) Ettre, L. S., in “Proceedings of the First National Symposium on Heterogeneous Catalysis for Control of Air Pollution,” pp. 349-58, National Air Pollution Control Administration, Cincinnati, 1969. (186) Ettre, L. S., and McFadden, W. H., “Ancillary Techniques of Gas Chromatography,” Wiley-Interscience, New York, 1969. \ - - - I
\ - - - - I -
, r
(187) Eustachio, A. J., ANAL. CHEM.40 [5], 19R (1968). (188) Evans, G. L.,Zbid.,40,1142 (1968). (189) Evans, hf. B., J . Chromatog., 30, 325 (1967). (190) Evans, M. B., and Smith, J. F., Zbid., 36,489 (1968). (191) Everett, D. H., Gainey, B. W., and Young, C. L., Trans. Faraday SOC.,64, 2667 (1968). (192) Fadeyev, G. N., and Gavrilova, T. B., Zh. Fiz. Khim., 42,3075 (1968). (193) Falk, F., and Dietrich, P., J . Chromatog., 33,411, 422 (1968). (194) Farre-Rius, F., and Guiochon, G., ANAL.CHEM.,40,998 (1968). (195) Farzane, N. G., and Ilvasov, L. V., Zh. Fiz. Khim., 42,3119 (1968). (196) Fatscher, &I.,and Vergnaud, J. M., Compt. Rend. Ser. C, 268 1039 (1969). (197) Favre, J. A. (to Phillips Petroleum Co.), U. S. Patent 3,403,978 (Oct. 1, 1968). (198) Fenimore, D. C., Zlatkis, A., and Wentworth, W. E., ANAL.CHEM.,40, 1594 (1968). (199) “Fifth International Symposium on Chromatography and Electrophoresis, Brussels, 1968,” Ann Arbor-Humphrey Science Publishers, Ann Arbor, hfich., 1969. (200) Filbert, A. hl., and Hair, M. L., J . Chromatog. Sci., 7,72 (1969). (201) Filbert, A. M . , and Hair, M. L., J . Gas Chromatog., 6,150 (1968). (202) Zbid., p. 218. (203) Findl, E., and Lui, K., Zbid., 6, 165 (1968). (204) Fink, P., and Wolleschensky, E., 2.Chem., 8,315 (1968). (205) Fish, D. W., and Crosley, D. G., J . Chromatog., 37,307 (1968). (206) Folmer, 0. F., Jr., and Azarraga, L. V., J . Chromatog.Sci., 7,. 665 (1969). 1207) Fowlis. I. A.. and Welti., D... Analvst. ‘ 92; 639 (1967). ’ (208) Franc, J., and Pour, J., J . C‘hromatog., 32, 2 (1968). (209) Franc, J., Trtik, B., and Platlek, K., Zbid., 36, 1 (1968). (210) Frank, A., Chemiker-Ztg., 93, 668 (1969). 1211) Frazer. J. W.. ANAL. CHEM.. . 40., ’ 26A (igssj. (212) Frazer, J. W. (to USA by AEC Commission), U. S. Patent 3,408,793 (Nov. 5, 1968). (213) Freedman, R. W., Lab. Pra,ct.,. 17,. 710(1968). ’ (214) Freeman, S. K., in “Ancillary Techniques of Gas Chromatography,” L. S. Ettre and W. H. McFadden, eds., pp. 227-67, Wiley-Interscience, New York, 1969. (215) Funasaka, W., Kojima, T., and Seo, Y., Bunseki Kagaku, 17,464 (1968). (216) Furuya, T.: Kojima, H., and Sato, H., Chem. Pharm. Bull., 15, 1362 (1967). (217) Gainey, B. W., and Young, C. L., Trans. Faraday SOC.,64,349 (1968). (218) Gehrke, C. W., Roach, D., Zumwalt, R. W., Stalling, D. L., and Wall, L. L., “Quantitative Gas-Liquid Chromatography of Amino Acids in Proteins and Biological Substances. Macro, Semimicro and Micro Methods,” Analytical Biochemical Laboratory, Columbia, Mo., 1968. (219) Gehrke, C. W., Zumwalt, R. W., and Wall, L. L., J . Chromatog. 37, 398 (1969). (220) Geiss, F., Versino, B., and Schlitt, H., Chromatographia, 1,9 (1968). (221) Geiss, F., Versino, B., and Schlitt, H., Z . Anal. Chem., 236,136 (1968). (222) “General Test Methods, 1968 Book of ASTM Standards, Part 30,” ASTM Designation E 255-68, pp. 1203-10, ASTM, Philadelphia, Pa., 1968. ~
ANALYTICAL CHEMISTRY, VOL. 42, NO. 5, APRIL 1970
17 R
(223) “General Test Methods. 1968 Book
- \-””.,.
I Giddings, J. C., J . Gas Chromatoa., _ . . 2,’167 (196&).’ (228) Giddings, J. C., and Keller, R. A., eds., “Advances in Chromatography,” Vol. V, (1968);Vol. VI (1968); Vol. VII, (1968); Vol. VI11 (1969), hlarcel Dekker, New York. (229) Giddinns. J. C.. M.yers, M. N., and King, J. W:,’J. Chiomdog. Sci., 7, 276 ~
( 1 969). \ - - - - I
(230) Giddings, J. C., Myers, M. N., PlIcLaren, L., and Keller, R. A., Science, 162,67 (1968). (231) Gill, J. M., and Hartmann, C. H., J . Gas Chromatog., 5,605 (1967). (232) Ginskey, R. A., and Schmidt-Bleek, F., J . Chromatog. Sci., 7,371 (1969). (233) Gladney, H. M., Dowden, B. F., and Swalen, J. D., ANAL.CHEM.41, 883 (1969). (234) Goedert, M., and Guiochon, G., J . Chromatoa. Sci. 7.323 (1969). (235) Goforth; R. R.,‘ and‘Harris, W. E., Chem. Instr., 1,95 (1968). (236) Golay, hl. J. E., ANAL.CHEM.,40, 382 (1968). (237) Golav. M. J. E.. Z. Anal. Chem.. 236,38 (i968). (238) Goldbaum, L. R., Domanski, T. J., and Schloegel, E. L., J . Gas Chromatog., 6,394 (1968). (239) Golovnya, R. V., and Uraletz, V. P., J . Chromatog., 36,276 (1968). (240) Gorbach, S., and Wagner, U., J . Agr. Food Chem., 15,654 (1967). (241) Goretti, G., Liberti, A., and Nota, G., in “Gas Chromatography, 1968,” C. L. A. Harbourn and R. Stock, eds., pp. 22-30, Elsevier, New York, 1969. (242) Goretti, G. C., Liberti, A., and Kota, G., J . Chromatog.,34,96 (1968). (243) Grant, D. W., J . Gas Chromatog., 6, ~
18 (1968). \----r
(244) Grant, D. W., Z. Anal. Chem., 236, 118 (1968). ( 2 9 ) Gray, T. A,, and Kuczynski, E. R., Environmental Pollution Instrumentation,” R. L. Chapman, ed., pp. 68-75, Instrument Society of America, Pittsburgh, 1969. (246) Green, L., Facts and Methods, 8 (6), 2 (1967). (247) Grice, H. W., and David, D. J., J . Chromatog. Sci., 7,239 (1969). (248) Grob, K., Helv. Chim. Acta, 51, 718 (1968). (249)-Grob, K., and Grob, G., J . Chromatog. Sei., 7,515 (1969). (250) Grob, R. L., Weinert, G. W., and Drelich. J. W.. J . Chromatoa.. 30., 305 (1967).‘ (251) Groenendijk, H., andvanKemenade, A. W. C., Chromatographia,2,107 (1969). (252) Grubner, O., “Advances in Chromatography,” J. C. Giddings and R. A. Keller, eds., Vol. 6, pp. 173-209, Marcel Dekker, New York, 1968. (253) Grunberger, C., Z. Anal. Chem., 236,22 (1968). (254) Grushka, E., Dissertation Abstr., 28, 3669-B (1968). (255) Grushka, E., Myers, M. K., Schettler, P. D., and Giddings, J. C., ANAL. CHEM.,41,889 (1969). (256) Guenther, E., Gilbertson, G., and Koenig, R. T.,Zbid., 41 [5],40R (1969); (257) Guichard, N., and Buzon, J., in “Manuel Pratique de Chromatographie “
18R
0
I
en Phase Gazeuse,” J. Tranchant, ed., pp. 155-96, Masson et Cie, Paris, 1968. (258) Guiffrida, L., and Ives, N. F., J . Assoc. Ofic. Anal. Chemists, 52, 541 (1969). (259) Guillemin, C. L., Auricourt, M. F., Du Crest, J., and Vermont, J., J . Chromatog. Sci., 7,493 (1969). (260) Guillemin, C. L., Auricourt, F., and Vermont, J., Chromatographia, 1, 357 (1968). (261) Gunther, F. A., and Barkley, J. H., Bull. Environ, Contam. Toxicol., 1, 39 (1966). (262) Gunther, F. A., Lopez-Roman, A., Asai, R. I., and Westlake, W. E., Zbid., 4,203 (1969). (263) Gvozdovich, T. N.,Kiselev, A. V., and Yashin, Y. I., Neftekhimiya, 8, 476 (1968). (264) Halasz, I., U. S. Patent 3,405,551 (Oct. 15, 1968). (265) Halass, I., Z . Anal. Chem., 236, 15 (\l-R-f-i _ R \,..
(266) Halasz, I., and Deininger, G., Ibid., 228,321 (1967). (267) Halasz, I., Deininger, G., Gerlach, H. 0..J . Chromatoa..35. l(1968). (268) Halasz, I., and“Seb&tian, I.,’ Angew. Chem., 81, 464 (1969); (Intern. Ed.), 8, 453 (1969). (269) Hamilton, C. H., “Instrumentation in Gas Chromatography,” J. Krugers, ed., pp. 33-52, Centrex, Eindhoven, 1968. (270)Hancock, H. A., and Lichtenstein, I., J . Chromatog. Sci., 7,290 (1969). (271) Harbourn, C. L. A., and Stock, R.. eds., “Gas Chromatography, 1968,’’ Elsevier, New York, 1969. (272) Hargrove, G. L., Dissertation Abstr., 28,4034B (1968). (273) Hargrove, G. L., and Sawyer, D. T., ANAL.CHEM.,40,409 (1968). (274) Harkness, R. A., and Torrance, A. M., Clin. Chim. Acta, 18,489 (1967). 1275) Harris. R. J.. U. S. Patent 3.385.113 , , (iday 28, f968). ’ (276) Hartmann, C. H., J . Chromalog. Sci., 7, 163 (1969). (277) Hartmann, C. H., U. S. Patent 3,417,238 (Dec. 17, 1968). Abstr., (278) Hartzoe. 1278) Hartzog, D. G., G.. Dissertation Abstr.. 29,2856B (1969). (279) Harvey, G. R., U. S. Patent 3,368,(2795 385 (Feb. 13,1968). (280) Hatch, R., J. Gas Chromatog., 6, 611 (lam) (1968). (281) Hautala, E., and Weaver, M. L., JJ.. Chem. Educ.. 46. 122 (1969). (282) Hawkes, S:J.,’J. Chomaiog. Sci., 7, 526 (1969). (283) Hawkes, S. J., and Nyberg, D. G., ANAL.CHEM.,41,1613 (1969). (284) Hay, P., Chromatographia, 1, 265 (1968). (2%5)Zbid.. D. 347. (286) Herr;;, C. B., J . Gas Chromatog., 6, 470 (1968). (287) Heyns, K., Sperling, K. R., and Grutzmacher, H. F., Carbohydrate Res., 9,79 (1969). (288) Hicks, C. P., and Young, C. L., Trans. Faraday SOC.,64,2675 (1968). (289) Hill, D. W., and Newell, H. A,, J . Chromatog., 32,737 (1968). (290) Hites, R. A., and Biemann, K., ANAL.CHEM., 40,1217 (1968). (291) Hoffman, R. L., and Evans, C. D., Ibid., 38,1309 (1966). (292) Hogan, V. D., and Taylor, F. R., Zbid., 40,1387 (1968). (293) Homing, E. C., Clin. Chem., 14, 777 (1968). (294) Hupe, K.-P., Chromatographia, 1, 57 (1968). (295) Zbid., p. 462. (296) Hupe, K.-P., Busch, U., and Winde, K., J . Chromatog. Scz., 7, 1 (1969). ~
\ - - - - ,
\--VU,.
ANALYTICAL CHEMISTRY, VOL. 42, NO. 5, APRIL 1970
(297) Hurley, E. K., Burke, M. F., Heveran, J. E., and Rogers, L. B., Separation Sci., 2,275 (1967). (298) Hurley, E. K., Burke, M. F., Heveran, J. E., and Rogers, L. B., in “Separation Techniques in Chemistr and Biochemistry,” R. A. Keller, e x , pp. 255-262, Marcel Dekker, New York, 1967. (299) “Identification of Textile hlaterials,” 5th ed., pp. 86-90, Textile Institute Publishers, Manchester, England, 1B6R ----. (300) Ilie, V., Rev. Chim (Bucharest), 20, 43 (1969). (301) Ina, K., and Sakato, Y., Bunseki Kagaku, 17,1316 (1968). (302) Znd. Res., 11 [12], 16 (Nov. 20,
-1B6Q) _--
(303) fnokuchi, H., Wakayama, N., Kondow, T., and Mori, Y., J . Chem. Phys., 46,837 (1967): (304) “International Symposium IV. Chromatographie: Electrophorese,” Presses Academiques Europeenes, Bruxelles, 1968. (305) Isbell, A. F., and Sawyer, D. T., ANAL.CHEM.41,1381 (1969). (306) Ivanova, N. T., and Zhukhovitskii, A. A., Zhur. Fiz. Khim., 41, 1923 (1967). (307) Janak, J., and Hainova, O., Chem. Prumysl, 18,308 (1968). (308) Janak, J., Svojanovsky, V., and Dreissler, M., Collection Czech. Chem. Commun., 33,740 (1968). (309) Jancso, G., and Kiss, I., Isotopenpraxis, 4,220 (1968). (310) Javadov, S.P., Kiselev, A. V., and Nikitin, Y. S., Zhur. Fiz. Khim., 41, 1131 (1967). (311) J. Chromatog. Sci., 7 [ 5 ] ,G2 (1969). (312) Jentzsch. D.. and Kuhne. K. (to ‘ Bodenseeweik Perkin-Elmer),’ U. ’S. Patent 3,390,513 (July2, 1968). (313) Jentzsch, D., and Schumann, W., Zbid., 3,365,951 (Jan. 30, 1968). (314) Jequier, W., and Robin, J., Chromatographia, 1,297 (1968). (315) Jitsu, Y., Kudo, N., Sato, K., and Teshima, T., Bunseki Kagaku, 18, 169 (1969). (316) Johns, T., and. Sternberg, J. C., “Instrumentation in Gas Chromatography,” J. Krugers, ed., pp. 179-207, Centrex, Eindhoven, 1968. (317) Johnson, H. W., Jr., in “Advances in Chromatography,” J. C. Giddings and R. A. Keller, eds., Vol. 5, pp. 175-228, hlarcel Dekker, New York, 1968. (318) Johnson, J. F., and Barrall, E. RI., J . Chromatoa.. 31.547 (1967). (319) Johnson; ’R. D., J : Gas’Chromatog., 6,43 (1968). (320) Jones, C. E. R., Proc. SOC.Anal. Chem., 6,98 (1969). (321) Jones, H. J., in ::The Practice of Gas Chromatography, L. S.Ettre and A. Zlatkis, eds., pp. 333-72, Interscience, New York, 1967 (322) Joshi, R. K., and Saxena, S. C., Indian J . Technol.,5,241 (1967). (323) Juvet, R. S., and Dal Nogare, S., ANAL.CHEM.,40 [SI, 33R (1968). (324) Juvet, R. S., and Pesek, J., Zbid., 41, 1456 (1969). (325) Juvet, R. S., Shaw, V. R., and Khan, M . A., J . Amer. Chem. SOC.,91, 3788 (1969) \----,.
(326) Kaiser, R., Chromatographia, 1, 34 (1968). (327) Zbid., p. 199. (328) Kaiser, R., Stoll, W., and Fischer, K., Zbid., 2,20 (1969). (329) Kamada, H., Iwata, K., and Ogahara. I.. Bunseki Kaaaku. 16. 1203 (1967). ’ (330) Kamada, H., and Kokubun, N., Ibid., 17,575 (1968). (331) Kambara, T., Hato, K., and Obzeki, K., J . Chromatog., 37,304 (1968). I
,
.
(332) Kambara, T., and Saitoh, K., Zbid., 35,318 (1968). (333) Karas, E. L., U. S. Patent 3,339,582 (Sept. 5, 1967). (334) Karasek, F. W., Res./Develop., 20 [4], 39 (1969). (335) Zbid., 20 (8),34 (1969). (336) Zbid., 20 (lo), 74 (1969). (337) Karayannis, N. M., and Corwin, A. H., Anal. Biochem., 26,34 (1968). (338) Karayannis, N. M., Corwin, A. H., Walter, J. A., Baker, E. W., and Klesper, E., ANAL.CHEM.,40,1736 (1968). (339) Karger, B. L., and Hartkopf, A., Zbid.. 40.215 (1968). (340) Karger, B. L.; Hartkopf, A., and Posmanter, H., J . Chromatog. Sci., 7, 315 (1969). (341) Karmen, A.,Zbid., 7,541 (1969). (342) Karohl, J. G., J . Gas Chromatog., 5, 627 (1967). (343) Karohl, J. G., in “Gas Chromatography, 1968, C. L. A. Harbourn and R. Stock, eds., pp. 359-66, Elsevier, New York, 1969. (344) Kashima, J., and Yamazaki, T., Bunseki Kagaku, 16,1379 (1967). (345) Kawahara. T.. Goto. S.. and Kash‘ iwa, T., Zbid., 18, 698 (1969): (346) Kazimerz, J., Lasa, J., and Ostrowski, K., Chem. Anal. (Warsaw), 13, 1239 (1969). (347) Kelker, H., and Verheist, A., J . Chromatog. Sci., 7, 79 (1969). (348) Kelker, H., and Von Schivizhoffen, E., in “Advances in Chromatography,” J. C. Giddings and R. A. Keller, eds., Vol. 6, pp. 247-97, RIarcel Dekker, Sew York, 1968. (349) Kelley, J. D., and Walker, J. Q., ANAL.CHEM.,41,1340 (1969). (350) Kelley, J. D., and Walker, J. Q., J . Chromatog. Sci., 7, 117 (1969). (351) King, W. H., Res./Develop., 20 (4), 28 (1969). (352) Zbid., 20 ( 5 ) ,28 (1969). (353) King, W. H and O’Connor, R. T., J . Am. Oil Chemists’ SOC..45.559 (1968). (354) Kingsley, G. R., ANAL: CHEM.,41 [ 5 ] ,14R (1969). (355) Kirkland, J. J., Ibid., 41, 218 (1969) ,-~”-,. (356) Kiselev, A. V., hligunova, I. A., Savinov, I. M., and Yashin, I., Neftekhimiya, 8, 643 (1968). (357) Kiselev, A. V., Migunova, I. A., and Yashin, Y. I., Zbid., 7,807 (1967). (358) Kiselev, A. V., Petrov, G. M., and Shcherbakova, K. D., Zhur. Fiz. Khim., 41,1418 (1967). (359) Kiselev, A. V., and Yashin, Ya. I., “Gazo - Adsorbtsionnaya Khromatografiya,” Nauka, Moscow, 1967. (360) Kishimoto, K., and Kinoshita, K., Bunseki Kagaku, 18,588 (1969). (361) Kleiman, R., Spencer, G. F., Earle, F. R., and Wolff, I. A., Lipids, 4, 135 (1969). (362) Klesment, I., J . Chromatog. 41, 1 (1969). (363) Klesment, I., and Krasnoschtschokova, R., Zbid., 37,385 (1968). (364) Knapman, C. E. H., ed., “Gas Chromatography Abstracts-1967,” Elsevier, Sew York, 1968. (365) Knapman, C. E. H., ed., “G: Chromatography Abstracts-1968, Elsevier, New York, 1969. (366) Knapp, O., Chromatographia, 2, 67 (1969). (367) Ibid., p. 111. (368) Zbid., p. 121. (369) Knox, J. H., and Saleem, M., J . Chromatog. Sci., 7,614 (1969). (370) Kochloefl, K., Schneider, P., Komers, R., and Jost, F., Collection Czech. Chem. Commun., 32, 2456 (1967). (371) Kojima, T., Seo, Y., and Nishida, J., BunzekiKagaku, 17,1496 (1968).
(372) Komers, R., and Kochloefl, K., Collection Czech. Chem. Commun.. 32. (3
(407) Levy, R. L., Gesser, H., and Hougen, F. W., Ibid., 41,1480 (1969). (408) Levy, R. L., Gesser, H. D., and Hougen, F. W., J . Chromatog., 30, 198 ( 1 967).
I
.
(1968). ’ (376) Krakow, B., ANAL.CHEM.,41, 815 (1969). (377) Krejci, M., and Rusek, M., Collection Czech. Chem. Commun.,, 33.. 3448 (1968). (378) Krugers, J., ed., “Instrumentation in Gas Chromatography,” Centrex Publishing Co., Eindhoven, 1968; distributed in the U. S. and Canada by Preston Technical Abstracts Co., 2101 Dempster St., Evanston, Ill., 60201. (379) Zbid., pp. 53-70. (380) Krugers, J. F. J., U. S. Patent 3,424,449 (Jan. 28, 1969). (381) Kupel, R. E., and Scheel, L. D., Am. Znd. Hyg. Assoc. J . , 29 [ l ] , 27 (1968). (382) Kuppens, P. S. H., “High Resolution Gas Chromato raphy in Steroid Analysis: An Introfiuction to the Use for Clinical Purposes,” Technische Hogeschool, Eindhoven, Holland, 1968. (383) Kwa, T. L., Korver, O., and Boelhouwer, C., J . Chromatog., 30, 17 (1967). (384) Kwok, J., Fett, E. R., and Mickelson, G. A., J . Gas Chromatog., 6, 491 (1968). (385) Kwok, J., Synder, R. L., and Sternberg, J. C., ANAL.CHEM.,40, 1 18 (1968). (386) Lai, C., and Roth, J. A., Chem. Eng. Sci., 22, 1299 (1967). (387) Lambert, C., U. S. Patent 3,336,493 (Aug. 15, 1967). (388) Landault, C., and Guiochon, G., Chromatographia, 1,119 1968). (389) Zbid., p. 277. (390) Langer, S. H., and Sheehan, R. J., in “Progress in Gas Chromatography,” J. H. Purnell, ed., pp. 289-323. Interscience, New York, -1968. (391) Langer, S. H., Yurchak, J. Y., and Patton. J. E., Znd. Ena. Chem.., 61.. 11 (1969): (392) Langer, S. H., Yurchak, J. Y., and Shaughnessey, C. RL, ANAL.CHEM.,40, 1747 (1968). (393) Lanning, E. W., and Weberling, R. P., Zbid., 40,626 (1968). (394) Lasa, J., Chem. Anal. (W‘arsaw),13, 1071 11968). (3951 Zbid.. i.1255. (396) Lasa, &J.,and Lesniewska, B., Zbid., 13,1247 (1968). (397) Lavoue, G., J . Gas Chromatog., 6, 233 (1968). (398) Lavrovskii, K. P., Rozental, A. L., and Denisova. T. A.., Neftekhimiva. , - , 8., 332 (1968). (399) Lebbe, J., in “Manuel Pratique de Chromatographie en Phase Gaseuse,” Jean Tranchant, ed., pp. 234-59, Masson et Cie, Paris, 1968. (400) Lehrle, R. S., Lab. Pract., 17, 696 (1968). (401) Levins, R. J., and Ikeda, R. XI., J . Gas Chromatog., 6,331 (1968). (402) Levy, E. J. (to Hewlett-Packard), U. S. Patent 3,425,807 (Feb. 4, 1969). (403) Levy, E. J., and Paul, D. G. (to Hewlett-Pacltard). Ibzd.,. 3,329,005 (July . . 4, 1967). (404) Levy, E. J., Radvany, I., Goland, D., Chant, L., and Malatesta, T. If.,in “Gas Chromatography, 1968,” C. L. A. Harbourn and R. Stock, eds., pp. 36778, Elsevier, Sew York, 1969. (405) Levy, R. L., J . Chromatog., 34, 249 ~
(1968) \----,.
(406) Levy, R. L., and Fanter, D. L., ANAL.CHEM.,41, 1465 (1969).
(409j -Levy, R. L., Gesser, H. D., and Westmore, J. B., Zbid., 32,740 (1968). (410) Levy, R. L., Walker, J. Q., and Wolf, c.J ANAL.CHEM.,41,1919 11969). (411) Liber?i, A., Nota, G., and Goretti, G., J . Chromatog., 38,282 (1968). (412) Liptay, G., Bekassy, S., and Takhcs, J., Zbid., 34, 1 (1968). (413) Liptay, G., Bekassy, S., and Takhcs, J., Magy. Kem. Folyoirat, 74,511 (1968). (414) Littlewood, A. B., Chromatographia, 1,37 (1968). (415) Ibid., p. 133. (416) Zbid., p. 223 (417) Littlewood, A. B., J . Gas Chromatog., 6,65 (1968). (418) Zbid., p. 353. (419) Littlewood, A. B., Z. Anal. Chem., 236,39 (1968). (420) Littlewood, A. B., Gibb, T. C., and Anderson, A. H., “Gas Chromatography, 1968,” C. L. A. Harbourn and R. Stock, eds., pp. 297-318, Elsevier, New York, 1969. (42ij~lewellyn, P. M., U. S. Patent 3,398,505 (Aug. 27,1968). (422) Llewellyn, P. M., and Littlejohn, D. P.. Zbid.. 3,429,105 (Feb. 15, 1969). (423) Louis, R.; Z. Anal: Chem.,’ 234, ‘161 11968). (424) Lovelock, J. E., ANAL. CHEM.,37, 583 (1965). (425) Lovelock, J. E., in “Gas Chromatography, 1968,” C. L. A. Harbourn and R. Stock, eds., pp. 95-106, Elsevier, New York, 1969. (426) Lovelock, J. E., Charlton, K. W., and Simmonds, P. G., ANAL.CHEM.,41, 1048 (1969). (427) Lubkonitz, J. A., Dissertation Abstr., 29,1580 (1968). (428) Lucero, D. P., and Haley, F. C., J . Gas Chromatog., 6,477 (1968). (429) Lucero, D. P., and Krupnick, A. C., ANAL.CHEM.40,1222 (1968). (430) Luft, R., and Pin, C., Compt. Rend., Ser. C, 266,537 (1968). (431) Lunar Sample Preliminary Examination Team. Houston. Tex.. Science, 165, 1211 (1969). (432) Lundstrom, J., and Agurell, S., J . Chromatog., 36,105 (1968). (433) Lynn, T. R., U. S. Patent 3,407,647 (Oct. 29, 1968). (434) Lysyj, I., and Nelson, K. H., AA-AL. CHEM.,40,1365 (1968). (435) Lysyj, I., and Nelson, K. H., J . Gas Chromatog., 6, 106 (1968). (436) hlacnonell, H. L., ANAL. CHEM.,40, 221 (1968). (437) hlacDonel1, H. L., and Eaton, D. L., Zbid., 40, 1453 (1968). (438) MacGregor, R. F., Clin. Chim. Acta, 21, 191 (1968). (439) RlacLeod, W. D., J . Agr. Food Chem., 16,884 (1968). (440) MacLeod, W. D., J . Food Sci., 33, 436 (1968). (441) MacLeod, W. D., and Nagy, B., ANAL.CHEM., 40,841 (1968). (442) hlajer, R. J., L K B Instr. J., 15, (l),11 (1968). (443) ‘‘Manual on Hydrocarbon Analysis,” 2nd ed., ASTM Philadelphia, 1968. (444) Martin, A. J. P., Scott, R. P. W., and Wilkins. T.. Chromatoaraphia, 2, 85 ” . (1969). (445) Rlarinetti, G. V., ed., “Lipid Chromatographic Analysis,” Vol. 2, RIarcel Dekker, New York, 1969. (446) Martire, D. E., Instr. S e w s , 18 [3]1, I
,
12-12 (1968)
(447) Martire, D. E., Blasco, y. A., Carone, P. F., Chow, L. C., and Vicini, H., J . Phys. Chem., 72,3489 (1968).
ANALYTICAL CHEMISTRY, VOL. 42, NO. 5, APRIL 1970
19 R
(448) Masukawa, S., Alyea, J. I., and Kobavashi. R., J . Gas Chromatoa., - , 6.266 . (19681. ‘ ’ (449) Masukawa, S., and Kobayashi, R., Zbid., 6,257 (1968). (450) Zbid., p. 461 . (451) Mazor, L., Molnar, E. B., Kaplar, L.. and Takhcs. J., Zbid., 6,401 (1968). (452) hlazor, L.; Papay,‘ B. K., Kiraly, K. E., and Takdcs, J., J . Chromatog., 36, 1 R (1968). \ - - - - I
(4j3) Mazor, L., Papay, AI., Rajcsanyi, P., and Takdcs, J., Magy. Kem. Folyoirat, 74,465 (1968). (454) Mazor, L., and Takdcs, J., J . Gas Chromatog., 6,58 (1968). (455) Mazor, L., and Takdcs, J., Magy. Kem. Folyoirat,73,310 (1967). (456) Zbid., 75,253 (1969). (457) hlazor, L., and Taklcs, J., Periodica Polytech., 13, 223 (1968). (458) hlccoy, Ii. W., and Cram, S. P., J . Chromatog. Sci., 7, 17 (1969). (459) hIcCrea, P. F., and Purnell, J. H., Nature, 219,261 (1968). (460) RlcCullough, R. D., J . Gas Chromatog., 5,635 (1967). (461) McKinney. C. B., and Sheppard, W. M., U. S. Patent 3,374,660 (March 26, 1968). (462) hIcKinney, R. W., Light, J. F., and Jordan, R. L., J . Gas Chromatog., 6, 97 (1968). (463) hIcLaren, L., hlyers, bl. N., and Giddings, J. C., Science, 159, 197 (1968). (464) McNair. H. hl.. and Bonelli. E. J.. “Basic Gas’ Chromatography,” ’Variai Aerograph, Walnut Creek, Calif., 1969. (465) PvlcU‘illiam, I. G., and Bolton, H. C., ANAL.CHEW,41,1755, 1762 (1969). (466) Mead, A. S., and Speakman, F. P., Chromatographia,2,211 (1969). (467) Mefferd, R. B., Summers, R. U., and Clayton, J. D., J . Chromatog. 35, 469 (1968). (468) hleier, W., and Huber, hI., Chem. Zng. Tech., 39,797 (1967). (469) hlerritt, C., Bazinet, h3. L., and Yeomans, W. G., J . Chromatog. Sci. 7, 122 (1969). (470) Mikes, O., and Chalmers, R. A., “Laboratory Handbook for Chromatographic Methods,” Van Kostrand, New York, 1967. (471) hlikkelsen, L., J . Gas Chromatog., 5, 601 11967). (472) hlilaho, B., Petrakis, I., and Borwn, P. M., Appl. Spectry. 22,574 (1968). (473) hIiller G. A., and Wells, C. E., J . Assoc. Offic. Anal. Chemists., 52.. 548 (1969). 1474) hlirva. S.. and Tatematsu. A.. Bunseki Khgakh, 17,816 (1968). (475) hlitchell, T. H., Ruzicka, J. H., Thomson, J., and Wheals, B. B., J . Chromatog., 32, 17 (1968). (476) Nohnke, hl., J . Gas Chromatog., 6, 117 (1968). (477) hlohnke, RI., Piringer, O., and Tataru, E., Zbzd., 6, 117 (1968). (478) blolera, hl. J., Dominquez, J. A. G., and Biarae. J. F.. J . Chromatoa. Sci.. 7. 305 (196$).’ (479) Rlorrow, R. W.,Dean, J. A., Shults, W. I)., and Guerin, bl. R., Zbid., 7, 572 (1969). (480) hlotley, R., and Meloan, C. E., Separation Sci., 3, 285 (1968). (481) hlunnik, J., and Fabrie, C. C. hl., 2. Anal. Chem., 236,5l (1968). (482) Alyakishev, G. Y., l i s p . Khim., 36, 1484 (1967). (483) hlyakishev, G. Y., and Vitt, S. V., Vestn. H o s k . Univ., Ser., Khim., 1967, 27. (484) hlyers, A., and Watson, L., Xature, 223,964 (1969). (485) Nakagawa, T., Miyajima, K., and Uno, T., J . Gas Chromatog.,6,292 (1968). ~
I
\
I
I
,
I
20 R
.
(486) Nakashima, S., and Toei, K., Talanla, 15,1475 (1968). (487) Nebel. C.. and Mosher. W. A.. J . Gas Chromatog.,6,483 (1968j. (488) Neidhardt, J. W., Dissertation Abstr., 28,3265B (1968). (489) Nelson, K. H., and Lysyj, I., Water Res., 3, 357 (1969). (490) Nishi, S., and Horimoto, Y., Bunseki Kagaku, 17,75 (1968). (491) Zbid., p. 1247. (492) Nonaka, A.,Zbid., 16,1166 (1967). (493) Novak, J., and Janak, J., U. S. Patent 3,354,696 (Kov. 28,1967). (494) Novak, J., Wicar, S., and Janak, J., Collection Czech. Chem. Commun., 33, 3642 11968). (495) Novo&, hI., Chromatographia, 2, 350 (1969). (496) Novotny, hI., and Tesarik, K., Zbid., 1,332 (1968). (497) Nowak. A. V..’ Dissertation Abstr.. 29; 510 B (1968). (498) Nowak, A. V., and Malmstadt, H. V., AKAL.CHEM.,40,1108 (1968). (499) Nowak, A. V., and hlalmstadt, H. V., J . Chem. Educ., 45,519 (1968). (500) Noweir, M. H., and Cholak, J., Environ. Sci. Technol.,3,927 (1969). (501) Nunnikhoven, R., Z. Ana!. Chem., 236,79 (1968). (502) Oberholtzer, J. E., and Rogers, L. B., ANAL.CHEM.,41,1234 (1969). (503) Zbid., p. 1590. (504) Obst, D., J . Chromatog., 32, 8 (1968). (506) Odland, R. K., Glock, E., and Bodenhamer, N. L., J . Chromatog. Sci., 7, 187 (1969). (506) O’Donnell, J. F., Amer. Lab., 1969, 31. (507) O’Donnell, J. F., U. S. Patent 3,357,157 (Dec. 12,1967). (508) O’Keefe, P. W., Wellington, G. H., Stouffer, J. R., and Mattick, L. R., J . Food Sci., 33, 188 (1968). (509) Onuska. F.. and Janak. J.. Chem. ‘ Ziesli, 22,929 (1968). (510) Oster, H., and Oppermann, F., Chromatographia, 2, 251 (1969). (511) Otte, E., Zbid., 1,231 (1968). (512) Overfield, C. V., and Winefordner, J. D., J . Chromatog.,30,339 (1967). (513) Pacdkovl, V., and Smolkovl, E., Chem. Anal. (Warsaw), 14,3 (1969). (514) PaclkovA, V., and SmolkovB, E., J . Gas Chromatog.,6,426 (1968). (515) Padberg, G., and Smith, J. hI., J . Catalysis, 12, 172 (1968). (516) Page, F. hl., and Woolley, D. E., ANAL. CHEM.,40, 210 (1968). (517) Palamand, S. R., and Thurow, D. O., J . Chromatog., 40,152 (1969). (518) Papendick, V. E., Sutherland, J. W.,and Williamson, D. E., ANAL. CHEM.,41 [ 5 ] , 190R (1969). (519) Parcher, J. F., Dissertation Abstr., 28,1387 (1967). (520) Parkinson, R. T., and Wilson, R. E., J . Chromatog.,37,310 (1968). (521) Pattison, J. B., “A Programmed Introduction to Gas-Liquid Chromatography,” Sadtler Research Laboratories, Philadelphia, 1969. (522) Paukov, V. N., Rudenko, B. A., and Kucherov. V. F.. Zh. Analit. Khim., 23,1247 (1968). (523) Paushmann, H. H., J . Gas Chromatog., 6,321 (1968). (524) Pauschmann, H., VIth Symposium on GC, Berlin, Abstracts of Papers, pp. 429-38, hlay 1968. (525) Pease, H. L., J . Agr. Food Chem., 16,54 (1968). (526) Pease, H. L., and Kirkland, J. J., Zbid., 16,554 (1968). (527) Pecsok, R. L., and Windsor, M. L., ANAL. CHEM.,40,92 (1968). (528) Zbid., p. 1238. \
-
,
~
ANALYTICAL CHEMISTRY, VOL. 42, NO. 5, APRIL 1970
I
,
(529) Pennington, S. N., J . Chromatog., 36,400 (1968). (530) Perry, S. G.,“ in ‘‘Advances in Chromatography, Vol. 7, J. C. Giddings and R. A. Keller, eds., pp. 221-40, Marcel Dekker, New York, 1968. (531) Perry, S. G., J . Chromatog. Sci., 7, 193 (1969). (532) Perry, S. G., Proc. SOC.Anal. Chem., 6,98 (1969). (533) Petho, A., and Schay, G., Chromatographia, 2,158 (1969). (534) Petryayeva, G. S., Timofeyeva, Y. A., and Shuykin, N. I., Neftekhimiya, 8, 628 (1968). (53.5) Petsev, N., and Dimitrov, C., J . Chromatog., 34,310 (1968). (536) Phen, Chon-Ton, Chim. Anal. (Paris),50,601 (1968). (537) Philippe, R., and Merlin, J. C., Bull. SOC.Chim. France, 1968,1247. (538) Phillips, C. S. G., “Progress in Gas Chromatography,” J. H. Purnell, ed., pp. 121-52, Interscience, New York, 1968. (539) Pitak, O., Chromatographia, 2, 304 (1969). (540) Pitt, P., Zbid., 1,252 (1968). (541) Porker t, H., Glas-Znstr.-Tech., 13, 557 (1969). (542) Pommier. C.. and Guiochon., G.., Chromatographia,2,346 (1969). (543) Popov, A. G., Zh. Prikl. Khim., 41, 127 (1968). (544) Porasil C., product of Waters, Inc., Framingham, Mass. (545) Porael, R., Exptl. Tech. Physik, 15, 173 11968). (546) Prager, M. J., and Deblinger, B., Environ. Sci. Technol., 1, 1008 (1967). (547) Pratt, G. L., and Langer, S. H., J . Phvs. Chem.,73,2095 (1969). (548j Preston‘ Technical Abstracts Co., 2101 Dempster St., Evanston, Ill., 60201: abstracts, Journd of Chromatographic Science, and literature retrieval devices. (549) Prevot, A., Andreani, J. C., and Taboureau, J., Rev. Franc, Corps Gras., 15,465 (1968). (550) Price. J. G. W.. Dissertation Abstr., 28; 114B j1967). ’ (551) Price, J. G. W., Fenimore, D. C., Simmonds, P. G., and Zlatkis, A., ANAL. CHFM.,40,541 (1968). (552) Proksch, E., Bruneder, H., and Granzer, V., J . Chromatog. Sci., 7, 473 (1969). (553) Purer, A., Hoffman, C. A., and Smith, D. R., J . Gas Chromatog., 6, 153 (1968). (554) Purnell, J. H., ed., “Progress in Gas Chromatography,” Interscience, New York, 1968. (555) Ramachandran, S., Rao, P. V., and Cornwell, D. G., J . Lipid Res., 9, 137 ~
~
flSA81. j - _ _ _
(556) Rassoul, S. A., J . Chromatog. Sci., 7, 380 (1969). (557) Reichke, A., Wandel, M.,Borger, H., and Tengler, H. (to Farbenfabriken Baver Aktienaesellschaft), U. S. Patent 3,421,857 (Jar;. 14,1969). ’ (558) Reiner, E., Beam, R. E., and Kubica G. P., Am. Rev. Respirat. Diseases, 99, 750 (1969). (559) Reiner, E., and Kubica, G. P., Zbid., 99,42 (1969). (560) Reznikov, S. A., Zh. Fiz. Khini., 42, 1730 (1968). (561) Riva. M.. and Carisano,. A.,. J . Chromatoo.. 36.269 (1968). (562) Robeits, D‘. R., ’ J . Gas Chromatog., 6, 126 (1968). (563) Rohrschneider, L., Chromatographia, 1,108 (1968). (564) Rohrschneider,. L... J. Chromatog., 22; 6 (1966). (565) Zbid., 39,383 (1969). ~
~
(566) Rohrschneider, L., J.Gas Chromatog. 6 , 5 (1968). (567) Rohrschneider., L.,. Z. Anal. Chem.. 236,149 (1968). (568) Kosen, A. A,, Safferman, R. Mashni, C. I., and Romano, A. Appl. hlicrobiol., 16,178 (1968). (569) Ross, W. D., and Sievers, R. ANAL.CHCM.,41, 1109 (1969). (570) Ross, W. D., and Sievers, R. Talanta, 15,87 (1968). (571) Rotin, V. A,, Zavodsk. Lab., 1446 (1967). (572) Roy, F., J . Gas Chromatog., 245 (1968). (573) Rudenko, B. A.. Zh. Analit. Kh ‘ 23; 341 (1968). (574) Ryan, J. AI., Timmins, R. S., and O’Donnell, J. F., Chem. Eng. Progr., 64 [ 8],53 (1968). (575) Hyhage, R., and Sweeley, C. C., Chem. Eng. A‘ews, 44 (lo), 48 (19G6). (576) St. John, L. E., and Lisk, D. J., J . Agr. Food Chem., 16,48 (1968). (577) Ibid., p. 408. (578) Saint-Yrieix, A., and Lesimple, C., Bull. SOC.Chim. France, 1967,4365. (579) Sanders, H. J., Chem. Eng. News, 47 [43],33(1969). (580) Sanders, W. K., and Maynard, J. B., ANAL.CHhM., 40,527 (1968). (581) Sanford, I
