Gas Chromatography - Analytical Chemistry (ACS Publications)

Anal. Chem. 1994,66, 621R-633R

Gas Chromatography Gary A. Eiceman' Department of Chemistry and Biochemistry, New Mexico State University, Las Cruces, New Mexico 88003-000 1 Herbert H. Hili, Jr. Department of Chemistry, Washington State University, Pullman, Washington 99 164 Behnam Davani Sigma Chemical Company, St. Louis, Missouri 63 178 Review Contents Column Theory and Techniques Column Theory Column Techniques Liquid Phases Synthetic Organic Phases Chiral Phases and Natural Phases Inorganic Salts and Metal-Based Phases Production of Liquid Phases Solid Supports and Adsorbents Natural Adsorbents Synthetic Adsorbents Sorption Processes and Solvents Structure/Retention Studies Aspects of Solubility Thermodynamic and Physical Parameters Wall Coated Open Tubular Columns and Multidimensional Chromatography Wall Coated Open Tubular Columns Multidimensional Chromatography GC Detection Methods Gas-Phase Ionization Photometry Electrochemistry Bulk Property Detection Multiple Detection Methods Gas Chromatography/Mass Spectrometry Qualitative and Quantitative Analysis Methods, Standards, and Interlaboratory Studies Simulations, Predictions, and Optimizations Quantitative Approaches to Retention Indexes Quantitative Advances

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This review of the fundamental developments in gas chromatography (GC) includes articles published from 1990 to 1991 and some works that appeared late in 1989. The literature was reviewed principally using CA Selects for Gas Chromatography from the Chemical Abstracts Service and some significant articles from late 1991 may be missing from the review. The related technique of gas chromatography/ mass spectrometry (GC/MS) is also incorporated in this review. Notable changes have been made in the organization and content of the review this year to reflect changes and trends within the practice or understanding of gas chromatography. 0003-2700/94/0366-0621$14.00/0 0 1994 American Chemical Society

Multidimensional chromatography was noted in the last review as a growing trend and has been merged with the section previously devoted to Wall Coated Open Tubular Columns. Additionally, the content within Qualitative and Quantitative Analysis has been wholly revised to stress the growing importance of computational tools for handling chromatographic information. The implications of such tools for studies at a fundamental level, or for new insights into chromatographic principles, have not been fully delineated. Summaries from some categories have been added as tables this year to shorten and clarify activity in those areas. Furthermore, emphasis has been made here, as in the recent past reviews, on providing a synopsis of major trends in GC rather than in compiling a comprehensive literature review. Previous reviews contained a section entitled Miscellaneous Information and this was eliminated for the current review. The whole of GC literature contains far more reports on the applications of gas chromtography than on the study of fundamental or elementary questions. However, the current review is a reminder that vigorous and diverse investigations and developments still are occurring in the subject of gas chromatography principles.

COLUMNTHEORYANDTECHNIQUES Column Theory. In this section, the understanding and influence of column parameters on chromatographic performance has been emphasized over investigations of solute/ solvent interactions or thermodynamics (vide infra). Column temperature was found to affect the polarity of a number of liquid phases and this was particularly evident with Carbowax, which exhibited a decline in polarity with increased temperature ( A I ) . Temperature effects on separation number (TZ) and height equivalent to a theoretical plate (HETP) occurred with a decreased T Z and HETP at elevated temperatures ( A 2 ) . This contradictory trend resulted in a net improved column efficiency, and results suggested that the T Z concept is based on sound chromatographic principles. The relative importance of mixed retention from partition versus adsorption was examined using alumina beads modified with bonded 0-phenethyl groups (A3). The relationship between number of surface groups and peak shape and retention volume was linear in agreement with a mixed mechanism providing a measure of the adsorption interactions. AnalyticalChemisiry, Vol. 66, No. 12, June 15, 1994 621R

Gary A. Eiceman is Professor of Chemistry at New Mexico State University in Las Cruces, NM. He received his Ph.D. in 1978 at the University of Colorado in Boulder, CO, and was a postdoctoralfellow at the University of Waterloo (Ontario, Canada) from 1978 to 1980. I n 19871988, he was a Senior Research Fellow at the U.S. Army Chemical Research, Development, and Engineering Center at Edgewood, MD, and in 1992 was a Senior Associate for the National Research Council fellowship program. He has been on the faculty at New Mexico State University since 1980. His research interests presently include the development of gas chromatography/ion mobility spectrometry, principles of gas-phase ion-molecule chemistry at atmospheric pressure, and the chromatography of natural materials. He has authored or co-authored over 100 research articles, reviews, or chapters and a book, Ion Mobility Spectrometry (CRC Press). He regularly teaches at undergraduate and graduate levels in electronics, quantitative analysis, and separations chemistry. *

Herbert H. Hill, Jr., is a professor of Chemistry at Washington State University where he directs an active research program in the development of instrumentation for trace organic analysis. His research interests include gas chromatography, supercritical fluid chromatography, ion mobility spectrometry, ambient pressure ionization sources, and mass spectrometry. He received his B.S. degree in 1970 from Rhodes College in Memphis, TN, his M.S. degree in 1973 from the University of Missouri, Columbia, MO and his Ph.D. degree in 1975 from Dalhousie University, Halifax, Nova Scotia, Canada. I n 1975 he was a postdoctoral fellow at the University of Waterloo, Ontario, and in 1983-1984 he was a visiting professor at Kyoto University, Kyoto, Japan. He has been on the faculty at Washington State University since 1976. Behnam Davani is Manager of the Chromatography Section in the Analytical Labe ratory, Sigma Chemical Co., St. Louis, MO. a He received his Ph.D. in 1985 at New Mexico State University. He was a postdoctoral research fellow at the U.S. Department of Energy, Morgantown Energy 6 Technology Center, Morgantown, WV, in 1986. Prior to joining Sigma Chemical Co., Dr. Davaniheld positions as Project Leader at Midwest Research Institute, Kansas City, MO (1987-9) and Analytical Organic Department Manager at Hall-Kimbrell Environmental Services in Lawrence, KS (1987-1 989). His research interests are the development of analytical techniques for separating and identifying organic compounds in chemical and pharmaceutical products using GC, GC/MS, LC, and capillary electrophoresis. Other areas of interest include the characterization and fate of trace organic compounds in complex environmental and energy related matrices. Dr. Davani has taught undergraduate cources at Maryville University, St. Louis, MO, as an Adjunct Faculty member.

Retention on columns was probed through comparisons with infrared spectrometry measurements to determine the stoichiometries of strong H-bond donor phases with solutes (A4). Hydrogen bond basicity of solutes was measured or scaled for 1:1 complexes; disagreements between retention and the free energies of complexation were attributed to changes in stoichiometriesof the complexes. A comparative study of retention on four unequally polar phases showed that programmed temperature retention indexes could be calculated using cubic spline interpolation; small differences against experimental findings existed for only a few solutes on a lowpolarity column (A5). The content of the reports in the 622R

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section above, the examination of past trends, and the absence of further reports suggest a mature or possibly stagnant condition for the subject of column theory. Column Techniques. Several new column methods were proposed with the hope that certain fundamental principles could be elucidated or explored. A step and pulse method was described to allow thecollection of equilibrium and kinetic data for multicomponent systems with emphasis on adsorption interactions (A6). Also, sorption effect chromatography was characterized for causes of noise (atmospheric pressure fluctuations) and recommendations were given to minimize noise in this method (A7). Continuous countercurrent gas/ liquid chromatography, long considered impractical, was evaluated in laboratory studies with simple mixtures (A8). Optimum conditions for a double-programmed GC (control of both temperature and column pressure) was accomplished using a new relationship utilizing separation numbers (A9). Column activity was degraded by acidic residues from oncolumn pyrolysis of lipid material and chromatographic activity was restored by treating the column with a diethylenetriamine scavenger (AZO). Chromatograms were simulated using dynamic phenomena to determine enantiomerization barriers and to distinguish between enantiomerization in the dissolved state versus the complexed state ( A l l ) . Precalculation of retention indexes through symbolic programming was successfully shown for alkanes and cycloalkanes (AZ2). Retention times were also used for deriving or estimating physical properties of polychlorinated biphenyls (AZ3). . Other developments in column techniques could be broadly classified as the sample to column interface (i.e., inlets) and high-speed chromatography as summarized in Table 1. Ifiterest in high-speed chromatography has increased, and the number and content of reports are suggestive of an intermediate state of development: some impressive findings have been reported (AZ6, A23) yet an understanding of core issues is incomplete, requiring parametric analysis (A22, A22). Activity with inlets for gas chromatographs was noteworthy for the interest in extending current limitations associated with traditional methods of introducing sample into a column.

LIQUID PHASES The themes of this section included the development and characterization of new or modified stationary phases for enhanced selectivity,thermal stability, and chiral recognition. The mechanisms of separation and solute/liquid-phase interactions were also evaluated through thermodynamic parameters obtained from retention data. The references cited below feature studies of an elementary nature. Synthetic Organic Phases. Several liquid crystals were investigatedto study the retention behavior of specific organic compounds and to assess the polarity and selectivity of these stationary phases. The retention behavior of dibenzothiophene derivatives was evaluated on a smectic liquid crystalline polysiloxane stationary phase (BZ). Theretention, in addition to vapor pressure and polarity, was greatly influenced by the molecular geometry of the solutes with the major contributing factor being the length-to-breadth ratio. The mechanism of interaction between a disk-shaped liquid crystal and a series of selected isomers was proposed (B2). Other crystalline

Table 1. Reports on Column Technology high-speed gas chromatography

refs

pressure programming for fast gas chromatography analysis of essential parameters for efficiency in high-speed GC description of high-speed GC for industrial hygiene monitoring ambient air analysis using fast gas chromatography microchip GC for ambient air analysis; a review consideration of the general elution problem by fast GC signal processing by neural systems in fast GC examination of influence of column diameter and film thickness on sample capacity and minimum detectable levels optimization of short column for GC/MS enantiomeric separations using short-column GC inlet or sample introduction methods

A22 A23

refs

large volume on-column technique with solvent distillation method solvent elimination for injections of large volumes on-line thermogravimetry GC/MS thermal modulation inlet for gas chromatography optimization of inlet parameters for aromatic hydrocarbon determination by GC liquid jet evolution from GC injector sample evaporation in conventional split/splitless injector

stationary phases were assessed for polarity (B3), thermal stability ( B 4 ) , and selectivity (B5). Stationary phases based on crown ethers were reported (B6,B7). The improved thermal stability of the adsorbent was attributed to a more uniform distribution of crown ethers on thesupport surfaceafter y-irradiation (B6).Theenhanced selectivityof crown ether polysiloxane phases for several groups of position isomers was ascribed to hydrogen bonding and the extent of fitting between the analytes and the crown ether cavity (B7). Highly selective phases based on arsenic and phosphoro-organic derivatives were reported (B8). In another study (B9), the roles of hydrolysis and oxidation under chromatography conditions for thermostable phases of siloxane polymers were discussed. Chiral Phases and Natural Phases. The most common chiral stationary phases were based on cyclodextrin and cylcodextrin derivatives (BIO-Bl7). The mechanisms of separation based on hydrophobic interactions and the change in cylcodextrin confirmation (BIO), steric interaction (BI I), and the size of inclusion cavity (BIZ) were discussed. The influence of the diluting phases on enantioselectivity (BI3) , the effect of analyte structure on stereoselectivity (BI 4 ) ,and contributions of the entropic and enthalpic parameters to chiral recognition (BZ5) were evaluated for modified cyclodextrins. Other mechanistic models for separation of special compounds such as epoxides and alcohols were derived (BI6,BI7). The chiral recognition mechanism on diamide chiral stationary phase was discussed (BI8). Coconut and hydrogenated soybean oils were used as natural stationary phases and evaluated for polarity and stability (BI9). Inorganic Salts and Metal-Based Phases. Only a few fundamental works were found in these areas. In one study, lithium, aluminum, and zinc nitrate solutions were used as liquid stationary phases for separation of unsaturated hydrocarbons (B20). Other reports described separation based on selective clathration for metal-amine (B21) and dithiocarbamate resin-metal complexes (B22). This last system was examined for those factors affecting retention and selectivity (B22). Production of Liquid Phases. A branched high molecular weight hydrocarbon with a single hydroxy group was syn-

A14 A15 A16 A17 A18 A19 A20 A2 1

A24 A25 A26 A27 A28 A29 A30

thesized to study polar forces in the separation processes (B23). Other new stationary phases based on crown ether derivatives were prepared and characterized for thermal stability and selectivity (B24-B27). The immobilization of the phase and the factors which affect the retention mechanisms including dipole/dipole interactions, hyrogen-bonding forces, and steric hindrance were also discussed in these articles.

SOLID SUPPORTS AND ADSORBENTS The emphasis in this section, as shown in the articles cited below, was solid surface characterization, surface modification or treatment, and determination of surface properties. Inverse gas chromatography (IGC) was a common method used to study adsorption processes and the interactions between the solid surface and the probe solutes. Natural Adsorbents. Several studies were reported on the characterization and chromatographic determination of the physicochemical parameters on carbon material (CI-C7). The effects of carbon surface modification using oxidation processes (CI-C3)and microwave plasma treatment (C4)were studied. The surface properties of activated carbon were examined from the results of the thermodynamic functions of adsorption (C5, C6). The surface polarity for a graphitized carbon fiber was measured based on linear free energy relationships (C7). Virial analysis of chloroflurocarbon adsorption on a microporous carbon was also reported (C8). The surface properties of silica modified with an aminopropyl group (C9), and amine and hydroxyl groups (CIO) were studied. The residual silanol groups in silica-based packings for liquid chromatography were estimated from gas chromatography retention data (CI I). Armstrong et al. (CI2, CI3)used cyclodextrins linked or bonded to silica gel as the packing support for separating a wide variety of inorganic gases (CZ2) and volatile hydrocarbons (CI3). Multiple retention mechanisms were observed for these solid stationary phases, and separation selectivities and efficiencies were compared to analogous silica gel support columns. A new numerical method was developed for calculating the adsorption energy distribution function from retentionvolume data (CI4). This parameter provided information about the interaction of solute molecules with solid surfaces and was used for Analytical Chemistry, Vol. 66, No. 12, June 15, 7994

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characterizing heterogeneous solids, glass, and silica gel. Chemically bonded alumina beads modified with 8-phenethyltrichlorosilane (C15) and colloidal aluminas (C16) were characterized for surface properties including retention behavior, surface energy, and acid/base interaction parameters. Roles and Guiochon (C17) used adsorption isotherm data for the study of the surface energy distribution of alumina ceramics. Two other natural materials studied were clays and cellulose. A review discussed the properties of bentons as sorbents for GC, colloid stationary phases based on bentons, their use for the separation of organic phases, and the mechanism of modification by liquid phases (C18). Isomeric cresols were separated on columns packed with Benton-34 + Castorwax on diatomaceous supports (C19). The adsorbents based on cellulose were also reported (C20, C21). The adsorption characteristics of alkanes on these modified cellulose materials were evaluated from the results of the thermodynamic functions and the London dispersive component of the surface free energy (C20, C21). Synthetic Adsorbents. Acid/base properties were characterized using IGC for polycarbonate (C22),chloride-doped polypyrrole (C23),and polydimethacrylates (C24). In another study, the chromatographic properties of Chromosorb- 103 were characterized in the variant of surface-layer sorbent (C25), Others studied radiation-modified sorbents containing nitro groups (C26) and Co(I1)-modified aminated methacrylate copolymers (C27). The contributions of nonspecific and/ or specific interactions were examined for these modified polymers. In another work (C28),a mathematical model used to calculate the strength characteristics of polymer composites was proposed.

SORPTION PROCESSES AND SOLVENTS The emphasis of this section is based on the development of models or equations to study different aspects of sorption and solubility. These topics have been grouped in the following three different categories with occasional and significant overlap among the sections. Structure/Retention Studies. Models were developed to study the relationship between the structures of tetra-nalkylsilanes and tetra-n-alkylgermane and retention using topological indexes (01). Most of the equations for these models were later improved for the same solutes ( 0 2 ) . The ability of a molecular connectivity model to predict retention indexes was evaluated for pesticides (03), tetralones, coumarins ( 0 4 ) , and structurally related compounds ( 0 3 , 0 4 ) . Several studies employing quantitative structure/retention relationship (QSRR) were reported for polychlorinated dibenzodioxines ( D 5 , 0 6 )and alkylbenzenes ( 0 7 ) . In another report (08),the relationship between chromatographic retention and thermal reactivity of polynuclear aromatic hydrocarbons was investigated. Methods for predicting the retention indexes from chemical structure were described for a wide range of compounds ( 0 9 , 010). Other models to predict the retention indexes for specific class of compounds such as alkylimidazoles (011), alkylbenzenes (D12), halogenated dioxins (Dl3-015), and hydrocarbons from naphthas (016) were also reported. The retention behavior of alkylated phenanthrenes on a smectic liquid cyrstalline phase was 824R

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explored ( 0 1 7 ) . In this work, the retention was related to molecular shapeconsiderations, and the influenceof the arclike shape of the phenanthrene molecule was investigated. In a noteworthy paper, the inclusion properties of dibenzo-24crown-8 ether were evaluated using retention behavior of a homologous series of alkanes, alcohols, ethers, aromatics, and halogenated hydrocarbons (018). Additionally, the interactions of crown ether with these substances were characterized and discussed in detail. Aspects of Solubility. Recent advances in solvation models for stationary-phase characterization and the prediction of retention were outlined by Poole et al. ( 0 1 9 ) . Also, two solvation energy models were compared for characterizing selectivity of stationary phases ( 0 2 0 ) . Good agreements between the two models were demonstrated for the contributions to retention in termsof cavity formation. Linear solvation energy relationships (LSER) were used to characterize stationary phases, and various terms in the LSER were related to different types of intermolecular interactions ( 0 2 1 ) . Carr proposed a triangle scheme for classification of gas chromatographic phase basedon thesolvatochromic linear solvation energy relationship ( 0 2 2 ) . The retention for a large number of solutes, spanning a very wide range in size, dipolarity, and hydrogen bond acceptor and hydrogen bond donor strength, as examined ( 0 2 3 ) . Other works on solvation parameters for alkylaromatic hydrocarbons (D24),alkylbenzenes ( 0 2 5 ) ,and a large number of other solutes were reported ( 0 2 6 , 0 2 7 ) . Tetraalkylammonium alkanesulfonate phases were examined as model solvents to quantitatively characterize the influence of fluorine substitution on retention ( 0 2 8 ) . Inverse gas chromatography was used to study polymer/solvent interactions ( 0 2 9 ) and polymer/solvent diffusion and equilibrium parmameters (030). Furthermore, Laffort solubility factors and topological indexes were evaluated and discussed in terms of structure/polarity relationships ( 0 3 1 ) . Thermodynamic and Physical Parameters. The focus of most of the research activities in this area included determination of enthalpies, entropies, free energies, and the activity coefficients. These measurements were used to describe the retention behavior as well as to characterize the solute/ stationary-phase interactions. The change in the enthalpy and entropy of methylene unit sorption for homologous series of carbonyl-containing compounds was shown to be due to interamolecular interaction between neighboring methylene andcarbonyl groups ( 0 3 2 ) . The retention behavior of a heterogeneous group of solutes on different stationary phases was examined ( 0 3 3 ) . The free energy relationship was used to predict retention of a series of aliphatic and aromatic compounds on fluoropolymer sorbents ( 0 3 4 ) . In this study, a correlation was established between the retention characteristics and Taft (inductive) substituent constants. Additionally, a mechanism was proposed for adsorbate/ polymer interaction. In other studies, the thermodynamic parameters of polymers with some aliphatic and aromatic probes were used to characterize the solute/surface interactions ( 0 3 5 , 0 3 6 ) . The activity coefficients in binary liquid mixtures were measured and deviations from the theoretical values as well as contributions from different factors were discussed (037,038).

TaMe 2. Multiple Dhnenrlon Chromatography gas chromatography/gas chromatography

refs

pattern determinations for terpenes in essential oils separation of chiral monoterpenes by GC/GC description of dual traps between column 1 and column 2 polarity changes in temperature programming coplanar conger separations of polychlorinated biphenyls identification of compounds in thinner chiral analysis of linalool in essential oils from fruits isomeric separations of chlorinated dioxins and furans characterization of gas from cracking process separations of polychlorinated biphenyls resolution of flavors by GC/GC/MS determination of vinyl chloride in poly(viny1 chloride) patent on switching system for column/column interface

E20 E2 1 E22 E23 E24, E25 E26 E27 E28 E29 E30-E32 E33 E34 E35

liquid chromatography/gas chromatography

refs

elimination of water in LC/GC interface with aqueous mobile phase direct silylation and determination of minor components in edible oils and fats detection of components in irradiated fat-containing foods determination of levamisole in milk determination of organophosphorus pesticides in fruits by LC/GC characterization of polar fraction of diesel particulate matter mixing in loop-type interface for LC.GC

E36, E37 E38 E39 E40 E4 1 E42 E4 3

supercritical fluid chromatography/gas chromatography

refs

description of interface for SFC/GC

E44

WALL COATED OPEN TUBULAR COLUMNS AND MULTIDIMENSIONAL CHROMATOGRAPHY The formative principle of wall coated open tubular (WCOT) columns, i.e., the chemistry of bonding and crosslinking, is no longer the subject of rapid advancement or innovation. The subject is relatively mature in the absence of dramatic advances in separation principles. However, there still exist innovations in WCOT column technology and these are occurring through creative applications of principles. Moreover, the dramatic rise in multidimensional chromatography of all types of configurations illustrates an instance where the practice of chromatography is leading to an appropriate theoretical framework including predictive and interpretive tools or optimization methods. Wall Coated Open Tubular Columns (WCOT). The development of metal WCOT columns as rugged alternatives to fused silica WCOT columns is based on the deposition of thin layers of silica on the inner wall of metal capillary tubing. The silica layer is then used for bonding stationary phases created for fused silica WCOT columns. Procedures for creating metal WCOT columns are still under development, and the deactivation or bonding chemistry in such columns was featured in several articles (EI-E3). Metal WCOT columns have been considered attractive because the coil radii can be made smaller than that possible for fused silica WCOT columns, for high mechanical durability, and for stability at elevated temperatures (>400 "C). Some activity occurred with conventional fused silica WCOT columns. Key components of modern capillary columns, i.e., immobilizing and cross-linking, were reported for immobilizing of chiral phases (E4-E6), free-radical crosslinking of chelate-laden phases (E7)and effects of cross-linking conditions on column performance ( E 8 ) . Notably, Berezkin et al. (E9) reported on mixed immobilized phases with WCOT columns, a possible advance in optimization of WCOT column performance when linked to chromatographic windows methods.

Column performance and the parameters that affect column performance peculiar to WCOT columns were investigated. For example, optimum performance from WCOT columns was attained through calculations from thermodynamic data (EIO). Moreover, the entire concept of column performance was reexamined and an original theoretical approach was proposed ( E l I). The challenge of introducing samples onto WCOT columns was approached using temperature-programmed injections ( E I 2 ) ,large-volume injections (EI3),and corrections of inlet discrimination from septum purge flows ( E I 4 ) . Matrix dependence for measurements using WCOT columns was shown to be associated with vaporization in the injector ( E I 5 ) , and decisions on split or splitless injection were associated with solvent polarity (EI6). Refined or subtle effects concerning WCOT columns were addressed in several articles. The isotope effect is theobserved differences in retention between a compound and a I4C-labeled or stable isotope analog (Le., isotopomers). Rosenblatt et al. ( E I 7 ) discussed the treatment of results for isotopomers by GC-MS, and Matucha associated lower molar volumes of isotopomers with elution order ( E I 8 ) . Compressibility in packed and WCOT columns was examined by Janssen et al. (EI9), who found that decompression of the mobile phase caused capacity factors to increase but HETP per unit time was unaffected. Multidimensional Chromatography. The subject of multidimensional chromatography (also known as two-dimensional chromatography or coupled column chromatography) has emerged in recent years as a substantial trend in gas chromatography. This area has been preoccupied previously with the mechanics of a suitable couple, or interface, between multiple GC columns or liquid chromatography (LC) with GC columns; this is now not the exclusive concern in multidimensional chromatography. The uses of multidimensional chromatography (see Table 2) have become numerous. Unfortunately, little has occurred in the elementary aspects of multidimensional chromatography such as optimization Analytical Chemistry, Vol. 66, No. 12, June 15, 1994

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or predictive modeling; however, nascent developments for information processing and future configurations of gas chromatographs may be anticipated to affect either abilities to make basic studies or provide a new challenge to those hoping to implement predictive or interpretive capabilities. For example, an integrated effort to create an estimate of total resolution of a GC/GC experiment was not evident in the literature reviewed. An objective in this section is to highlight patternsof activity within multidimensional chromatography so theoretical challenges or opportunities might be recognized. Currently, there are few, if any, theoretical foundations for multidimensional chromatography and no tools or rules for establishing data bases. Thus, the practice of multidimensional chromatography is highly empirical and not likely to be systematized. Nonetheless, several patterns in the current literature may be recognized. Serial GC/GC has been applied largely to determinations of flavors and chlorinated pollutants; a second column is used to further resolve constituents isolated from a single peak of a first column. In this configuration, differences in partition on a phase different from that of a first column provide a basis for improved isolation of a specific constituent from a complex matrix. Such is the case for essential oils (E20), paint thinner (E26), and flavors (E33). Other uses of GC/GC include the separation of highly similar molecules such as isomers of polychlorinated dibenzo-p-dioxins (E28) or polychlorinated biphenyls (E24, E25). The challenging combination of liquid chromatography with GC is seemingly in a level of development comparable to GC/GC. However, LC/GC seems to have been applied largely for natural products such as milk, fruits, and airborne particulate matter. With this configuration and with supercritical fluid chromatography, the interface is likely to remain as a component in need of further improvement. As with GC/GC, no attempts have been made to provide a theoretical foundation to the method and reports have been highly empirical to date.

GC DETECTION METHODS Criteria by which all chromatographic detectors can be compared are sensitivity, selectivity, band broadening, and response time ( F I ) . In addition, chromatographic detection methods can be categorized according to their mode of operation. Most GC detectors are based on one of several mechanisms: gas-phase ionization, photometry, electrochemistry, or bulk property measurements. The following sections discuss comparative criteria and fundamental advancements reported for GC detectors during the last two years for each of the categories listed above. Gas-PhaseIonization. Under the general category of gasphase ionization detection resides a number of well-known chromatographic detectors: the flame ionization detector, the helium ionization detector, the photoionization detector, the nitrogen/phosphorus detector, the surface ionization detector, the electron capture detector, and the ion mobility detector. Each of these detectors has experienced continued interest during the past two years. Flame Ionization Detector (FID). The flame ionization detector remains the most widely used detection methods for gas chromatography (F2). Response studies for esters (F3, 626R

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F4), paint solvents (F5),and polycyclic aromatic compounds (Fd)were reported for standard FIDs while in other research projects FID parameters were modified to obtain enhanced selectivity. The addition of a cracking reactor and catalytic hydrogenation microreactor between a column and an FID enabled the selective determination of oxygenated compounds (F7). Addition of methane to the remote FID (RFID) and flame thermionic ionization detector (FTID) improved selectivities of both detectors against carbon-containing compounds (F8). Detection limits of 1 pg/s for lead, tin, and phosphorus were reported with a selectivity over carbon of lo6. For standard FIDs, however, it was demonstrated once again that it is important to keep detector gases as clean as possible for minimal background and maximal response (F9). Clean gases and low flow rates permitted detection limits as low as 0.1 pg for several hydrocarbons (FIO). In addition to parametric studies, design modifications to the FID have been reported for a variety of applications and investigations. In one study, a fast-response FID (FRFID) was constructed to monitor hydrocarbons exhausted from individual cycles of auto engines (FI1). Instrumental aids for FIDs used as continuous hydrocarbon monitors include the addition of a second glow plug for greater efficiency (FI2) dual FID and GC-FID configuration (FI3), an air diluter (FI4), use of a Venturi nozzle for GC carrier gas (FI5,F l d ) , and a separate supply of calibration gas (FI7). Helium Ionization Detector (HID). The modern helium ionization detector offers sensitive analysis of higher molecular weight compounds (FI8). It is currently one of the most sensitive detectors available for gas chromatography. A new design for the detector was introduced in which a nonradioactive pulsed high-voltage discharge serves to generate and collect electrons in a helium atmosphere (FI9). A pulsed discharge helium ionization detector (PDHID) was found to be universal with detection limits on the order of 1-20 pg and a linear dynamic range of over 4 orders of magnitude. Photoionization Detector (PID). Designs for photoionization detection with capillary gas chromatography have improved significantly over the past few years (F2O). An ideal example of GC-PID is the determination of trace isoprene and monoterpenes in the atmosphere (F2I). A cylindrical UV lamp with a pin-shaped collecting electrode was able to detect benzene at the 5-pg level (F22). New designs coupled with multiphoton ionization approaches have received considerable attention over the past two years. A fiber-optic multiphoton ionization detector with detection limits down to 0.12ng was described for polycyclic aromatic hydrocarbons (F23). A graphite furnace was coupled to a miniflame laser enhanced-ionization detection system to provide 10-fgdetection limits for magnesium and indium (F24). NitrogenlPhosphorus Detector (NPD). Basic detector components, theory of operation, and response characteristics of this popular selective detector were reviewed (F25). New investigations with this detector revolved around response characterization after megabore capillary column chromatography (F26, F27) and a comparison of its response with that of the surface ionization detector discussed in the next section (F28). Surface Ionization Detector (SZD). The SID is similar in concept but broader in scope than the NPD. Its detection

mechanism involves positive surface ionization (F29). Response characteristics for phenothiazine derivatives (F30), diphenylmethane antihistaminic drugs (F31),and pentazocine (F32) were evaluated. Detection limits were about 2-5 pg for the best responding compounds. Electron Capture Detector (ECD). After the FID the ECD is the most used detector for gas chromatography. The constant-current ECD is the most common mode of operation but fixed frequency (FF-ECD) and chemically sensitized (CS-ECD) are often employed for specific objectives (F33). Response studies included methylmercury (F34), the antifungal drug fluconazole (F35) and nitroglycerin along with its mono- and dinitrate metabolites (F36). A particular disadvantage to ECD has been the need for a radioactive source to produce electrons. A novel nonradioactive source for generating electrons was presented based on the interaction of far-IR irradiation with amines (F37). Another type of ECD which did not require a radioactive source was based on a pulsed, high-voltage discharge in helium (F38). Called a pulsed-discharge electron-capture detector (PDECD), its operation is similar to the pulsed-discharge emission detector (PDED), and the pulsed-discharge helium ionization detector described elsewhere in this review. Test applications of this PDECD for CFCs and halogenated pesticides gave detection limits in the subpicogram and low-femtogram range. Zon Mobility Detector (ZMD). An IMD is more sensitive than FID or PID with sensitivity similar to the ECD and offers multiple response modes which make it a versatile, sensitive, and selective detector for gas chromatography (F39). Molecular selectivity of the IMD against matrix interferences was demonstrated by the detection of mammalian lignans in urine and blood (F40). Qualitative and quantitative investigations were conducted for a variety of halogenated compounds (F41).Large variations in the responses of these compounds were noted as a function of IMS temperature and composition of the carrier gas. Responses of a variety of pesticides were obtained and compare with that of a pulsed ECD (F42). The pulsed ECD was found to be more sensitive tocarrier gas flow conditions that the IMD. As an alternative to the radioactive source normally employed in the IMD, a photoionization source was proposed for the detection of explosives (F43). It was claimed that the detector could detect explosives 10-100 times lower than conventional explosive detectors. Finally, the concept of portable hand-held gas chromatography ion mobility spectrometry was introduced with the construction of a portable GC-IMS device and the separation and detection of mixtures of phosphonates, phosphates, alkyl ketones, and chlorophenols in under 2 min (F44,

F45). Other Ionization Detectors. Many of the energy sources which produce light emission and are discussed below also produce ionization. The ionization responses of many of these sources were also considered as detection methods for GC. By comparing the signal immediately before and after a long delay relative to a high-voltage spark discharge, slow mobility ions can be observed (F46). Microwave ionization detection methods were also investigated. Ionization in the MIP source occurs by MIP emitted photons and electrons (F47) with detection limits for benzene at the 2 pg/mL level (F48).When this detector was interfaced to a portable GC, results compared

well with conventional portable GC thermal conductivity detection (F49). The last typeof ionization detector presented in this review is the radioactivity detector. One novel detector was for the detection of halides of short-lived nuclides. Separated according to their volatility by gas chromatography, these nuclides then passed into an ionization chamber (F50). The entire system was called a heavy element volatility instrument (HEVI). In another method, the gas stream was entrained in a flowing liquid solvent so that some of the analytes were transferred into the liquid phase. Detection was accomplished with a liquid radioactivity monitor (F.51). Photometry. GC detection based on the interaction of matter with light includesatomic emission, molecular emission, atomic absorption, and molecular absorption. Atomic Emission Detection. The majority of research and development in photometric detection after gas chromatography has been in the area of atomic emission spectrometry (AES) (F52). The primary energy sources used for GC detection have been microwave-induced plasmas (MIPS). Detection and response have been evaluated for petroleum products (F53.F M ) , halogenated compounds (F55),organotin compounds (F56, F57),organomercury compounds (F58), and organometallics in general (F59). One of the more novel applications of GC/AES was the determination of metals in soils by supercritical fluid complexation and extraction followed by GC/AES detection (F60). Investigationsof cavity designs for inexpensive construction (F61) and atmospheric operation (F62) were reported. Interferences from solvents were eliminated with a novel solvent-venting technique while incorporating a reversed-flow step while the solvent is eluting from the column (F63). Vacuum-assisted solvent elimination was also described (F64). In a factorial analysis of parameters, forward power and flow rate of the plasma gas were found to be the most critical (F65). Noise from reflected power was found to be a function of the degree of power coupling to the cavity and to the flow rate of the plasma gas (F66). Temperature did not appear to have a major effect on noise. Radio frequency plasmas (RFPs) were found to have an oxygen/carbon selectivity of 1000 with a detection limit of 100 pg/s (F67). By doping an RFP with oxygen, detection limits of about 1 pg/s were achieved for bromine and chlorine with an element to carbon selectivity of 1000 (F68). The newly described pulsed-discharge emission detector (PDED) is similar in design to the pulsed-discharge helium ionization detector described above, except that emitted light serves as the analytical response (F69). Complete characterization of the PDED has not yet been done. Atomic emission spectra for metals in flames were also reported (F70). Detection limits were considerably lower than those reported for MIP and RFP methods. Molecular Emission Detection. While AES methods may also give rise to molecular emission spectra (F71), the most common GC detectors which involve the emission of light from molecules are the flame photometric detector (FPD) and the chemiluminescence detector (CD) (F72). For the FPD, burner configuration was investigated as a function of temperature distribution (F73) and the glass viewing window was heated to prevent response loss due to condensation of water (F74). A novel detector was based on adjusting a combustible gas flow rate to the point where it cannot sustain Analytical Chemktry, Vol. 66,No. 12, June 15, 1994

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a continuous flame (F75). Called a pulsed flame photometer detector (PFPD), this flame provides pulsed emitted light such that time domain information can be obtained from the detector signal. The main advantages claimed for the PFPD are improved detection sensitivity, higher selectivity, lower gas consumption, reduced emission quenching, temporal information, and the ability todetect other elements. Detection limits were reported to be 0.2 pg/s for S , 10 fg/s for P, 5 pg/s for N, and 60 pg/s for C. Chemiluminescence was investigated for the detection of nitrogen (F76-F78) and sulfur-containing compounds (F79). A novel method for detection of sulfur compounds was described in which a flameless combustion system was developed (F80).When this flameless S chemiluminescence detector was applied to the detection of sulfur compounds in petroleum products, it was found to be more sensitive than conventional sulfur detectors and performed with precision, linearity, and selectivity at least as good as conventional detectors (F81). Atomic Absorption Detection. In general, light-absorbing detection methods are less sensitive than light-emitting methods of detection because the presence of a positive signal on a blank background can be detected with higher sensitivity than can a small decrease in a large signal. Nevertheless, development of atomic absorption (AA) methods for GC has proved useful in several cases. For example, the determination of organotin compounds in water and sediment samples can be achieved with GC/AA techniques (F82). Molecular Absorption Detection. While molecular absorption detection methods are common in liquid chromatography, they are a novelty in gas chromatography. A lownoise, rapid-scanning UV/visible absorbance detector has been described for GC (F83) although the cell was designed for remote flow detection. The rapid-scan feature allowed onthe-fly collection of gas-phase absorption spectra. Far-UV absorption detectors have been developed from photoionization detectors and appear to provide increased sensitivity for many compounds (F84). By far the most commonly used GC detector based on molecular absorption of light is the infrared (IR) detector. Infrared absorption detection after gas chromatography has become routine over the past few years and although it remains less sensitive than many GC detection methods the rapid-scan capabilities of Fourier transform infrared detection offers the advantages of on-the-fly qualitative information (F85). Electrochemistry. The most widely used and accepted detection method based on electrochemistry is the electrolytic conductivity (F86) detector with application to halogen-, sulfur-, and nitrogen-containing compounds. Its detection chemistry and various detector designs have been adapted for capillary chromatography (F86). While the electrolytic conductivity detector relies on the absorption of ionizable gases into liquids for conductivity measurements, other electrochemical detectors have been investigated for direct gas-phase detection. An electrochemical gas/liquid chromatography detector was developed based on diffusion f plasticization phenomena (F87). Voltammetry, using a microring electrode, was investigated for organic vapors but did not appear to be sufficiently sensitive for trace analysis (F88). Fundamental investigations of microelectrodes found that response changed with time and was strongly influenced by the amount of sample 620R

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injected (8'89). These response characteristics were explained by high internal resistances coupled with nonlinear absorption of the components in the thin electrolyte layer. Bulk Property Detection. Detection methods falling into this category include thermal conductivity detectors (TCD), surface acoustic wave (SAW) crystal detectors, and detectors based on pressure and flow fluctuations. While TCDs have traditionally required detector volumes too large for efficient use with capillary chromatography, reduced-volume TCDs have been reported (F90), while quantification with TCDs has been facilitated by the development of a rapid diffusion method for determination of relative sensitivity coefficients (F91).The high response speed of SAW sensors enable their use with high-speed gas chromatography in which chromatographic elution and detection can be accomplished in 10-15 s (F92). Themost novel ofthe bulksensitivedetection methods was a detector which measured the change in pressure as a result of sorption effects of the analyte in the chromatographic column (F93). The sensitivity of this detector is limited by pressure noise due to atmospheric pressure fluctuations. These fluctuations can be caused by stormy weather or simply activity near the chromatograph. Methods to minimize pressure noise are described. Multiple Detection Methods. When two or more detectors are used for the same chromatographic separation, response ratios provide additional information for qualitative analysis. For years Aue and co-workers have demonstrated the advantages of multiple detection. Recently they developed a computer algorithm for multiple detection (F94). Using the response ratios from a dual-channel flame photometric detector, they illustrated the presence and nature of FPDactive elements. They also point out that response ratios can be used to assess peak homogeneity, confirm peak identity, and facilitate subtraction and element-specificchromatograms. Combinations of detectors have been used for a variety of applications. Riekkola and her group used PID/FID response ratios to corroborate retention index identifications of various chemical warfare agents (F95).The ECD was combined with the FID for the detection of 71 volatile organic compounds with detection limits from 0.09 to 0.01 pg/L (F96,F97). Even when mass spectrometry is available, the use of alternate detection methods helps to identify and quantify GC components. For complex mixtures the addition of Fourier transform infrared and atomic emission spectrometric detection aid in identification and structure elucidation (F98).An FPD was used to help a mass spectrometer speciate and quantify tributyltin compounds in aquatic matrixes (F99). While this section has focused on the novel and the highly technical innovations in GC detection during the past two years, it was comforting to note that one of the most complex, sensitive, and oldest GC detectors was still being utilized and developed. Selective detection using olfactometry was combined with nonselective detection to compare odor profiles of pinot noir wines (F100)from which wines from 1988 contained more odor-active peaks than those from 1987. GAS CHROMATOGRAPHY/MASS SPECTROMETRY The developments emphasized in the subject of gas chromatography/mass spectrometry (GC/MS) involve those concepts associated with (A) processing information to glean

Table 3. Summary of Qualltatlvo and Quantltatlvo Analyses methods, standards, and interlaboratory studies

refs

multivariate analysis of round robin of chlorophenols in fish oil validation for large carboxylic acids in medicinal products method 1613. Isotope dilution GC/MS for PCDDs and PCDFs interlaboratory validation of method 1613 standardized method for tetrachloroethylene in olive oil interlaboratory reproducibility of retention indexes interlaboratory study on chlorobiphenyl determination

H1 H2 H3 H4 H5 H6 H7

simulations, predictions, and optimization

refs

stationary-phase recommendation by expert system computer-assisted optimization of separation expert system for arson analysis by GC/MS prediction of retention and separation knowledge-based interpretation of GC results fitting of models for retention index data prediction of retention via computer-calculated molecular properties numerical simulation of temperature programming simplex optimization for separation of polychlorinated biphenyls (PCBs)

H8 H9 H10 H11 H12 H13 H14 H15 H16

pattern recognition and multivariate analysis of chromatographic results

refs

pattern recognition of chromatograms and sensory principle component analysis of pepper and sensory wine analysis by GC neural nets for vegetable oil characterization coca butter analysis classification through unique chemical markers in complex mixtures multivariate decision and detection limits 3-Dmultivariate visualization qualitative analysis, matching chromatograms with new algorithm multivariate analysis for quantitative GC jet fuel spills and pattern recognition GC biological activity of PCBs and RI as molecular descriptors

h17 H18 H19 h20 H21 H22 H23 H24 H25 H26 H27 H28

quantitative approaches to retention indexes (RI)

refs

review: recent advances in solvation models molecular connectivity indexes for chlorinated pesticides prediction of RI Kier-Hall total topological index oxygenated benzenes basic questions of reliability of retention time estimates for nonadsorbed gas variations in GC conditions on RIs total solubility parameter for RI calculations unified retention indexes comparison of four methods for RI prediction elution order calculation quantitative structure retention relationships for PCDDs

H29 H30 H3 1 H32 H33 H34 H35 H36 H37 H38 H39 H40

quantitative difficult challenges

refs

ion band multicomponent resolution method coelution and dual-isotope dilution by GC/MS relative response in dual-isotope dilution GC/MS tandem detectors for quantitative determination of overlapping peaks response ratio chromatography from dual-channel detector FID response factor using effective carbon number instrumental effects in isotope ratios by GC/MS

H41 H42 H43 H44 H45 H46 H47

additional information from data or (B) exploiting the unique capabilities of mass spectrometers to enhance the specificity of gas chromatographs. One such example was that of evolving factor analysis in GC-MS (GI) for computational resolution of overlapping chromatographic peaks. This was attempted using a large number of detection channels or nominal masses with multivariate techniques for data manipulation. Deconvolution of overlapping GC peaks was also the attempted with time array detection by time-of-flight mass spectrometry (GZ). Also, poor resolution in selected ion monitoring methods for complex mixtures was improved using a magnetic sector mass spectrometer with resolution of 3000 (G3).

A philosophy of handling data arose from highly complex data sets (i.e., pyrolysates of nucleosides) and was presented using feature selection and fingerprinting (G4). These two, when combined, showed GC-MS suitable for pattern recognition of different classes of nucleosides. Pattern recognition tools were also utilized for unresolved complex mixture of hydrocarbons after chemical oxidation. Clusters of data were observed through a multidimensional scaling program (G5). Eiceman et al. (G6)evaluated the logistic and economical principles for GC-MS in large-scale agricultural studies as a warning to those intending to use GC-MS for routine uses. The balance between using selectivity of the mass spectrometer Analytical Chemistry, Vol. 66, No. 12, June 15, 1994

62SR

in substitution of pretreatment of samples contain elevated backgrounds of interferences can lead to unanticipated compromises or elevated costs in management of environmental studies. Ion trap mass spectrometers were featured in two articles where a new ion trap scan function employed alternate mass selective storage for coeluting isotopically labeled internal standard and analyte (G7). Huston described the manipulation of ion trap parameters to enhance qualitative or compoundspecific information. In contrast, the quantitative (molar) responses for polychlorinated dioxins were shown to be structure dependent (G8). In a slightly different approach, to collect information from a chromatogram, daughter ion spectra were a basis for the determination of chemical warfare agent (G9). The growth in plasma mass spectrometry as a GC detector was evident in a review with 71 references (GIO). Several reports concerned on-site GC/MS (GI I, GI 2 ) with results that were statistically equivalent to standard laboratory-based EPA methods.

QUALITATIVE AND QUANTITATIVE ANALYSIS The contents of this section are completely redone from the 1992 review to reflect current challenges in qualitative and quantitative analyses. One trend has been to view chromatographic patterns as raw information, rather than as a finished product, for further manipulations. Such manipulations, based on computation capabilities in the current generation of desktop computers are potentially available now to a wide community of investigators. This subject has been subdivided into four categories of (A) Methods, Standards, and Interlaboratory Studies, (B) Simulations, Predictions, and Optimizations, (C) Quantitative Approaches to Retention Indexes, and (D) Quantitative Advances. Methods, Standards, and Interlaboratory Studies. Interlaboratory studies listed in Table 3 encompass diverse challenges for quantitative measurements involving samples with complex matrixes. In one study, Franke et al. ( H 6 ) proposed that temperature dependence in Kovat's retention indexes could be ameliorated using a homologous series of certain amine or nitro compounds; an improvement was reported for interlaboratory reproducibility with a drug mixture of 25 retention indexes with the polar homologs in comparison to 60 retention indexes for the same compounds referenced to normal alkanes. A second interlaboratory study was made on the quantitative determination of chlorinated biphenyl (CP) congeners (H7). Sixty-two laboratories from 16 countries participated in determination of CPs and deviations were attributed to incomplete calibrations (i.e., operating outside the linear range of an electron capture detector, reported here as only 15-750 pg) and difference or variations in resolution between two congeners. Simulations, Predictions, and Optimizations. Noteworthy in this section was the extraction of information from chromatographic data through principal-component analysis (H24). Nonorthogonally mapped matrixes were used to show clustering of similar chromatographic parameters to compare replicate analyses and to reduce the chromatogram to a single valueor coordinate. Applications were illustrated. A number of approaches were taken (Table 3), all toward a common 830R

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goal of recognizing similarities or differences in highly complex chromatographic profiles derived usually from natural materials such as foods or bacteria. Sahota and Morgan (H22) showed that recognizing chemical markers in chromatographic data should best be viewed with an understanding of the chemical basis for discrimination. Yet, Narasimhan et al. (HI8 ) demonstrated that even in the absence of molecular details, principal component analysis could direct or identify the key six compounds governing black pepper quality from over 25-30 peaks in the chromatogram of an oxygenated fraction. It is not clear presently how these computation tools will affect gas chromatography principles or practices. However, the use of such tools in probing chromatographic processes does not seem to be widely appreciated or applied. Quantitative Approaches to Retention Indexes. Solvation models continued to be an active area of study though the trend has been toward less activity in the last eight years. Specific uses of such models for the calculation of retention indexes has been especially subdued with fewer than a dozen articles identified for inclusion here. A trend in this review was the use of models for retention index calculation (i-e., prediction) with molecules which have comparatively large molecule weights, complex structures, and nontrivial intermolecular interactions. For example, models of several kinds were used successfully in the past two years for RI predictions with pesticides (H30), chemical warfare agents (H35), oxygenated benzenes (H33),and coumarins ( H 3 I ) . This was evident in the 1990 review and is notably different from the mid- to late- 1980s, when homologous series of alkanes, alcohols, amines, and substituted benzenes were core subjects of such models. Clearly, the sophistication and suitability of these models have improved during the last decade. QuantitativeAdvances. The primary interest in quantitative determinations by gas chromatography was the subtle effects observed with methods such as isotope based GC-MS (i.e., internal standard techniques), When stable isotope analogs elute at times different from the target chemical, ionization efficiencies may be variable due to effects from background interferences on MS ion source conditions. This is evident in complex samples with changing and occasionally unresolved backgrounds. Thomas (H42, H43) proposed that forced coelution of the target vapor and the isotopically labeled internal standard should result in comparable ionization efficiencies and improved certainty. Approaches to handling coelution occurred for both GCMS with an ion band method (H4I) and for dual detectors of FID with PID (H44). This latter method is rooted in solving multiple equations for response from detectors exhibiting differences in response to members of a coeluting pair. Aue et al. (H45) described response ratio chromatograms from a dual-channel flame photometricdetector to impart a chemical dimension to the physical dimension of quantity and retention.

LITERATURE CITED

(A2j (A3) (A4)

6

Jones, L. A.; Relss. W. Glennon, J.'J.'f Gerlg,, T. M. J. C / u m w . 1992, 5981-2). 221-38. WRo, K.; Kudo, K.;Takel, S. dnal. Sd. 1992, 42), 169-72. Ll, J.; Zhang, Y.; Ouyang, H.; Cam, P. W. J. Am. Chem, Soc. 1992, 114(25), 9813-28.

(A5) (AB) (A7) . . (AB) (Ag)

Garcla Domhrguez, J. A.; Santluste, J. M. J. C h m t o g r . 1992,627(12), 203-17. Granger, J.; Chue, K. T.; Kabk, H.; Remy, P.; Chanel, S.; Tondeur, D. Recents Rcg. Qenk Recedes 1991, 5, 29-35. Buffham, B. A.; Mason, G. J. Chmmatw. Sci. 1992, Meacham, R. I.; 3ql I), 459-64. Sato, K.; Motokawa, 0.; Watabe, K.; Ihara. T.; Hobo, T. Sep. Sci. Techno/. 1993, 28(7), 1409-20. Jones, L. A.; annon, J. J.; Relss, W. H. J. Ckomatogr, 1992.595(12). -,. 209-19. ---

(A10) Rrettl, M. V.; Paglluca. 0. J. Chromatog. 1991, 585(2), 342-4. ( A l l ) Jung, M.; Schurlg. V. J. Am. Chem. Soc.1992, 714(2), 529-34. (A12) Gautzsch, R.; Zlnn, P.; Haffer. C. M. Chemom. Intell. Lab. Syst. 1991, 72(1), 81-90. (A131 Flscher, R. C.; Wittllnger, R.; Ballschmiter, K. Fresenius J. Anal. Chem. 1992, 3434-9, 421-5. (A14) Peters, A.; Sacks, R. J. Chromatogr. Sci. 1992, 3 ~ 7 9 ,187-91. (A15) Vanes, A. J. J. Report 1990, ETN-91-98481. Order No. N9l-16113. Avail. NTIS. From: &v. Rep. Announce. Index 1991. 97(12), Abstr. No. 130,628. (A16) Mouradian, R. F. Report 1990, Order No. PB91-188631. Avail. NTIS. From: &v. ReD. Announc. Index 1991. 91f161. Abstr. No. 142.574. (A17) Ke. H.; Levlne, ‘s. P.; Berkley, R. J. Air Wasie &nap. Assoc. 1992, 4211). 1446-52. Cahey, K. R.; Wong, R. L.; Overton, E. 8.;Jacklsch, M. A.; Steele, C. F. Sampllng Anal. Alrborne Pdlut. 1993, 21-37. Ruby, W. A. J. High Re~dui.C h r ~ ~ ~ t o1991, g r . 74(6), 542-8. Palmer, D. A.; Achter, E K.; Lleb. D. Roc. SfE-Int. Soc. Opt. €ng. 1993, 7824, 109-19. VanEs, A. J. J. Report 1990, ETN-91-98481. Avail. NTIS. From: Sci. T&. AefOSp. Rep. 1991, 29(8), Ab&. NO. N91-16113. Rossl. S. A.: Johnson, J. V.; Yost, R. A. 8/01.Mess Smtrom. 1992, 27(9), 420-30. Undstrom, M. J. H&h Resolut. Chromatogr. 1991, 74ll), 785-7. Hller, J. F.; McCabe, T.; Morabito, P. L. J. Hi& Resolut. Chromatogr. 1993, 78(1), 5-12. Stanlewski, J.; Rljks, J. A. J. High Resdut. Chromatogr. 1993, 78(3),

.-- ..

lA3-7

(A26) Chung. H. L.; Aldrldge, J. C. Anal. Instrum. 1992, 2q2-3), 123-35. (A27) Sacks, R. D.; Klemp, M. A.; Rankln, C. L. US. Patent US 5,141,534 1992, US Appl. 590,174, 1990. (A281 Trevelln, W. R.; Vidal, L. H.; Landgraf, M. D.; Slhra, I.C. E.; Rezende, M. 0. Anal. Chim. Acta 1992, 2641). 67-71. (A29) Qlan, J.; Polymeropoulos, C. E.; Ullsse, R. J. Chromatog. 1992,609(12), 269-76. (A30) &ob, K.; Brem, S. J. Hhh Resdut. Chromatagr. 1992. 781l), 715-22. LIOUID PHASES

Budzlnskl, H.; Garrlgues, P.; Bellocq, J. J. Chromatog. 1992, 590(2), 297-303. Kraus, A.; Schumann, U.; Kraus. G.; Kohne, B.; Praefcke, K. J. UUOmatogr. 1992, 609(1-2), 277-81. Bet& T. J. J. ChrOt?78t*f. 1992, 605(2), 276-80. Krestov, A. 0.;Blokhlna, S. V.. Olkhovlch. M. V. Zh. Anal. Khim. 1992, 47(10-ll), 1864-8. Sojak, L.; Ostrovsky, L; Kubinec, R.; Kraus, G.; Kraus, A. J. Chromatogr. 1992, 609(1-2). 283-8. Chernoplekova, V. A.; Kovaleva. N. V.; Grlgor‘ev, E. L; Trakhtenberg. L. I.; Schcherbakova. E. S. Zh. Flz. Khlm. 1981, 657(11), 3028-32. Wu. C. Y.; Cheng, J. S.; Zeng. 2. R. Chromatographla 1993, 35(1-2), 33-7. Novlkov, V. F. Zh. Fiz. Khim. 1893, 67(4), 848-53. Fokln, A. A.; Sidel’nlkov, V. N. Sib. Khim. Zh. 1991, 3, 5-23. Venema, A.; Henderlks, H.; Van Geest, R. J. High Resolut. Chromatogr. 1991, 74(10), 676-80. StOeV, G. J. ChrOtnatOgf. 1992, 589(1-2), 257-63. Andrews, A. R. J.; Wu, 2.;Zhtkls, A. Chromatograph& 1992,34(9-IO), 457-60. Blcchl, C.; Artuffo, G.; D’Amato, A.; Manzln, V.; Galll, A.; Galll. M. J. High Resolut. Chromatogr. 1993, 76(4), 209-14. Smnh. I.D.; Slmpson, C. F. J. High Resolut. Chromatogr. 1992, 75(12), 800-6. Schurlgh, V.; Jung, M. Recent A&. Chiral Sep., [Roc. Chromatog. Soc. Int. Symp. Chhal Sep.], 2nd 7989 1990, 117-33. Relher, T; Hamann, H. J. J. High Resolut. Chromotogr. 1992, 75(5), 346-9. Koehler, J. E. H. ; Hohla, Ma.;Richters, M.;Koenlgh, W. A. Angew. Chem. 1992, 104(3), 362-4. Lou. X.: Llu. X.: Zhu. D.: Wana, Q.; Zhou. L. J. Chromatow 1992, 626(2), 231-8. Husain. S.: Sarma, P. N.; Sastw G. S. R.; Swami, G. Y. S.K.; Raju, N. P. Indhn J. Technoi. 1993. 37(2), 103-8. Berezkln, V. 0.; Viktorova, E. N. Zh. Anal. Khim. 1992. 47(5), 635-9. M. De& J. Sci. 1989, 73(1), 228-46. Soad, 2.M.; ECZeln, S. M; Yeh,C.F.;Chyueh,S.;Chen.W.S.;Fang.J.D.;Liu,C.Y. J.Chromatog. 1992. 63U1-2\. 276-85. Du&, J. C. Synthesis 1982, 10, 981-4. Zeng.Z.R.;Wu,C.Y.;Yan.H;Huang,Z.F.;Wang,Y.T.ClvometogrepMe 1992, 341-2), 85-90. Fu, R.; Jlng, P.; Gu, J.; Huang, 2.; Chen, Y. Anal. Chem. 1993, 65(15), 2141-4. Zeng, 2.;Wu, C.; Fang, X.; Huang, 2.;Wang. Y. J. Chromatogr. 1992. 589(1-2), 368-74.

Maw,

(827) Wu, C.; Cheng, J.; Gao, W.; Zeng. 2.;Lu, X.; Gong, S. J. C)vometog: 1992, 5941-2), 243-51. SOLID SUPPORTS AND ADSORBENTS Jagielb, J.; Bandosz, T. J.; Schwarz. J. A. J. &/MInterface Sci. 1992, 15(12), 433-45. (c2) Jagielb, J.; Bandosz, T. J.; Schwartz, J. A. Chromatogephle 1992. 33f9-10). 441-4. __ .- ~ . .(C3) Jacobasch, H. J.; Cirundke, K; Maeder. E.; Fretag, K. H.; Panzer. U. J. A ~ s Sci. . T&MI. 1992. 8112). 1381-96. (c4) Donnet, J. B.: Park, s. J.; kendC, M. carbon 1992, 3q2), 263-8. (C5) (Laljek, H.; Neffe,S.; Witklewkz, 2. J. Chrometogr. 1992, 6Oql). 6777. (C6) Lopez-Garcla, F. J.; Domlngez-Garcia,M.; Pyda, M. Leng7mk1993,9(2), 531-6. (C7) Park, J. H.; Lee, Y. K.; Donnet, J. B. Chromatopph/a 1992, 33(3-4), 154-8. (C8) Ryboit, T. R; Zang, X.; Wall, M. D.; Thomas, H. E.; Mullinax, L. E.; Lee, J. R. J. COWInterface Sci. 1992, 7482). 359-66. (C9) Dsvydov, V. Y.; Mandrugin, A. A.; Morozova, Y. G.; Roshchlns. T. M.; Fllatova, G. N. Zh. Fk. Khim. 1992, 68(3), 736-43. (C10) Grenterloustabt, M.-F.; Renotte-Greco, D.; Grenier, P. Ew. pdym. J. 1993, 29(9), 1185-96. (C11) Takeuchl, T.; Mlwa, T.; Nagae, N. Chrometograph& 1993, 35 (7-8), (C1)

,.---

375-80. .. .

(C12) Reid, G. L., III;Wall, W. T.; Armstrong, D. W. J. Chromatog. 1993, 6381-2). 143-9. (C13) R e d G.’.L., 111; Monge, C. A.; Wall, W. T.; Armstrong, D. W. J. Chrometogr. 1993, 633(1-2), 135-42. (C14) Heuchel, M.; Jaroniec, M.; Gilpln, R. K. J. Chromatop. 1993, 628(1), 59-67. (C15) Naito, K.; Kudo, K.; Takel, S. Anal. Sci. 1992, 42), 189-72. (C16) Papker, E.; Perrin, J. M.; Slffert, B. Frog. CdlddPdym. Sci. 1991, 84 (Trends Colbld Interface Sci. 5), 257-61. (C17) Roles, J.; Oulochon, G. J. Chromatog. 1992, 59(1-2), 233-43. (C18) Klrsch, S. L.; Vigdergauz, M. S. Zh. Anal. Khlm. 1991, 48(12), 2294313. (C19) Nardllb, A. M.; Castells, R. C.; Castells, C. 8. Chromatogmphia 1991, 3a9-10). (C20) Lee, H. L.; Luner, P.. J. WoodChem. Techno/. 1993, 13(1), 127-44. (C21) Kamdem, D. P.; Rledl, B. J. &l/oM Interface Sci. 1992, 750(2), 507-16. (C22) Panzer, U.; Schrelber, H. P. Mecromolecules 1992, 25(14), 3633-7. (C23) Pigoia-Landureau. E.; Chehlml, M. M. J. Appl. h w m . Sci. 1993, 49(1), 183-6. (C24) . . Voelkel. A.; Andrzelewsks, E.; Mega, - R.; Andrzelewskl. M. Po/ynw 1993, 3414), 3109Lll. (C25) Andronlkshvlll, T. G.; EprlkashvlHI, L. G.; Abulashvlll, E. L.; Leonldze, N. 219-23. M.; Kordzadhh. T. N. Izv. Akad. Muk @w.Ser. K h h . 1991, 77(3), (C26) Shepelenko, T. S.; Zlbarev, P. V. Sib. Khh. Zh. 1993, (2), 34-7. (C27) Platonova, N. P.; Ubgov, V. 0.: Hradll, L; Cvec, F. Zh. Flz. Khlm. 1992, 68(4), 1043-8. (C28) Babenko, E. V.; Kkplchnlkov. P. A.; Muratova. 0. Y.; Manyurov, I.R. Zh. ffikl. Khlm. 1992, 65(10), 2345-9. SORPTION PROCESSES AND SOLVENTS KUpChlk, E. J. J. Chrot7WtOQf. 1992, 603(1-2), 223-30. KUpchk E. J. J. ChfOnWW. 1993, 645(l),182-4. Helnzer, V. E. F.; Yunes, R. A. J. Chrometogr. 1992, 596(2), 243. Armde, A. C.; Helnzen, V. E. F; Yunes, R. A. J. Chromatop. 1992, 630(1-2), 251-6. Needham, M. D.; Jurs, P. C. Anal. Chim. Acta 1992, 258(2), 183-98. Needham, M. D.; Adams, K. C.; Jurs, P. C. Anal. Chlm, Acta 1992, 2542). 199-218. Mekenyan D. N.; Enchev, V. Anal. CMm. Acta 1992. 26ql). 69-74. GuHlen, M.D.; I@esks, M.J.;Do~guez,A.;Hlanco,C.G.J. chrometog. 1992, 597(1-2), 287-95. Peng, Y. 2. C.; Ding, S. F. J. Chmmatogr. 1991, 50, 85-112. Peng C. T. J. RadiOenal. Nucl. Chem. 1992. 76q2). 449-60. Golovnyss, R. R. ; Zhuravleva, I.L.; Sal’kova, M. A. Zh. Anal. Khim. 1992, 47(7), 1269-75. Peng,C.T.; Hua,R. L.; Maltby, D. J. Chromatgr. 1992.589(1-2). 231-9. Sovocod,G.W.;Donnelly,J.R.;Munsbw,W.D.Orgenohekgen~. 1990, 2(EPRI PCB-Semln., Anal. AQIQC. Brom. Compd., Short-Chaln AliPhatiCS), 361-4. Donnelly J. R. ; Sovocool G. W. J. Chromatog. 1992, 594(1-2), 28973. Maklno, M.; Kamlya. M.; Matsushlta, H. Chemosphere 1992, 25(12), 1839-49. Woloszyn, T. F.; Jurs, P. C. Anal. Chem. 1993, 65(5), 582-7. Budzlnskl, H.; Radke, M; Garrlgues, P.; Wise, S. A; Belkcq, W.H. J. chrometogr. 1992, 627(1-2). 227-39. Mnuk, P.: Smdkova-Keulemansova, E.: Feitl. L. J. Chromtogr. 1992. 623(2). 297-304. Poole, C. F.; Kollle, T. 0.; Poole. S. K. Chromatogaphh 1992.34(5-8). 281-302. Kollle. T. 0.; Poole. C. F.; Abraham, M. H.; Whitlng. 0. S. Anal. Chh. Acta 1992, 259(1), 1-13. Ballantine, D. S., Jr. J. Chrometogr. 1993, 628(2), 247-59. LI, J., Zhang. Y.; Carr, P. W. Anal. Chem. 1992, 64(2), 210-8. Ll, J.; Zhang, Y.; Carr, P. W. Anal. Chem, 1983, 65(15), 1969-79. Abraham, M. H.; Whiting, 0. S. J. Chromatogr. 1992, 594(1-2), 22941. Zhang, H.; Hu, 2 . Chromatograph& 1992, 33(11-12), 576-80.

Analytical Chemistry, Vol. 66, No. 12, June 15, 1994

631R

Akeham,M.H.;Whltlng,Q.S;Doherty,R.M.;~ly,W.J.Chtvmatog. 1991, 587(2), 213-28. Abraham, M. H.; Walsh, D. P. J. Chromatcg, 1992, 627(1-2). 294-9. Kollle, T. 0.; POOle, C. F. Clwomrtog.aphle 1992, 99111-12), 561-9. MpaobBaranyi, e, Hslao, C. K.; Spes, M.; OdeH, P. G.; Burt. R. A. J. A M . pd)m,Scl.: ApplP0l)m. Symp. 1992,51(Pdym. Anal. Charact. IV), 195-208. Romhane, I.H.; Danneir, R. P. A I M J. 1993, 39(4), 625-35. Voelkel, A. J. Chmmtogr. 1992, 629(1), 63-91. (klovnya, R. V.; c.Llgor’eva,b. N.; VasH‘ev, A. V. J. Redut. Chrometo@. 1991, 14(11), 741-4. Mehran, M.; Cooper, W. J.; Gdkar, N.; Nlckelsen; M. 0.;Mrmefehdn, E. R.; OUtMe, E.; Jenning, W. J. H&h ResoM. Chmmtogr. 1991, 741I), 745-50. Uiinskaya, N. N.; Shadrina, N. E.; Korsakov, V. 0.;Ivanchev, S. S. Zh, F k Khkn. 1992, 68(8), 2235-9. YHmaz, F.; Cankurtaran. 0. G.; Baysal, 6. M. Polymer 1992, 33(21), 4563-8. Zaltseva, V. V.; ArkusMne, V. I. Ep&s&ye, Al’nye Akr&tnye Mkn. 1990, 68-74. Kolledkne, A.; KareQkskls, G.; Katsanos, N. A.; Roth, M. J. Chmnatogr. 1992, 5931-2), 237-46. Castells, R. C.; Castells, C. B., J. SoMlon Chem. 1992,21(2), 129-46. WALL COATED OPEN TUBULAR COLUMNS AND WLTIDIMEMIONAL CHROMATOGRAPHY (€1)

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Zou, N.; Tsd, Y.; Sun,J.; Lu, W. J. Mgh Resofut.Chwnatcgr. 1993, 76(3), 188-91. Schuyler, A.; Stauffer, J. W.; Loope, C. E.; Vargo, C. R. ~ s s C o n t r o l Oual. 1992, q1-4), 187-71. Vonk, N.; De Zeeuw, J.; Buyten,J. Process ContfolOual. 1992, ql-4)’ 137-44. A b . I.; Kobara, H.; Wasa, T. Chm”o@aphb 1999,35(9-12). 503-

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iwancz, 2.; Qroilmwrd. K.; Francotte, E. CWab‘ly 1992,47), 459-61. Armstrong, D. W.; Tang, Y.; Ward, T.; Nichols, M. Anal. Chem. 1093. 638), 1114-7. Kowalski, W. J. Chrometogaphla 1092, 345-a), 266-8. Sandra, P.; Davld. F.; McNak, H. M. Anal& 1992, 2q3), 117-20. Berezkin, V. 0.;Smlryaeva, V. E.; Popova, T. P. Zh.Anal. M.1992. 47(5), 825-31, Leclercq, P. A. J. H$$I Resdut. chromatogr. 1992, 188). 531-4. Gaspar, 0. J. High Resolut. Chromatop. 1992, 15(5), 295-301. Stanlewskl, J.; RlJks,J. A. J. C h f o m s w . 1992, (Val), 105-13. Qrob.K.;Brem,S. J.~ResoIut.chrometogr.l992, lqll),715-22. Hinshaw, J. V. J. Resolut. Ctnumaw. 1999, 18(4), 247-53. E m y , D. R.; Wbsple, A. M.; Oilvydls, D. M.; Poole, C. F. J. Ckomtogr. 1998, 634l), 57-63. Qabran, M. T.; Moyano, E. J. Ctromtcgr. 1992, 607(2), 287-94. Rolenblatt,J.;Chinkes, D.;Wolfe, M.; WMe,R. R.Am. J. physiol. 1092, 2633, Part I). €584-96. Matucha, M.;Jockisch, W.; Verner, P.; Anders, G. J. Chnmatogr. 1991, 5841-2), 251-8. Janssen, H. G.; Snijders, H.; Cramers, C.; Schoenmakers, P. J. HI@ ReSdUr. C h m t m . 1002, 15(7), 458-86. Engewald, W.; Knobloch, T.; Haute, G.; Mueller, M.; Pohris, V. Fresenlus J. Anal. them. 1991, 347(10), 641-3. Askari, C.; Hener, U.; Schmarr, H. G.: Rapp, A.; Mosandl, A. Fresenlus J. AMI. Chem. 1991, 34q12), 768-72. Ragunathen, N.; Krock, K. A.; WUkins, C. L. Anel. Chem. 1993, 65(8), 1012-6. Chansgrlhe, N.; Eaallouamer, A. J. Ctwmtogr. 1993,6331-2), 163-

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Himberg, K. K.; Slppda, E. Chemosphere 1999, 27(1-3), 17-24. “ b s r g , K.; slppok E. W J W ~ 1990, ~ 4, 183-8. K M , K. A.; Wiklns, C. L. Anal. Chh. Acta 1999, 27312). 381-8. Bemreuther, A.; Schreier. P. phytochm. Anal. 1991, q4), 167-70. Dew, F.; Sandra, P.; Hoffmann, A.; Gerstd, J. chrome-@& 1992, 345-8), 259-65. Yang, H.; Ren, S.; Lu, W. Sepu 1992, l q l ) , 9-13. Kannan, N.; Petrlck, 0.;Schulz, D. E.; Dulnker, J. C.; Boon, J. P.; Van Arnhem, E.; Jansen, S. W n m m Con@. 1990, 2, 165-8. Kannan, N.; Sohulz-Bull, D. E.; Patrlck, G.; Duhrker, J. C. Int. J. Envkon. AMI. them. 199P, 413). 201-15. Larsen. B.; Bowadt, S.; Faccheffl, S. Int. J. fnvkon. Anal. Chem. 1992, 47(3), 147-66. N k . S.: Weinrelch, B.;Drawert, F. J. H@hReso/ut.Chmarogf. 1002, 136). 387-9 1. Wrlght. D. W.; Mahler, K. 0.; Davis, J. J. Chmmatop. Sei. 1992, 30(8), 291-5. Ugon. W. V., Jr. US. Patent US 5,108,468, 1991. Mol. H. G. J.; Staniewski, J.; Jansm, H. G.; Cramers, C. A.; Qhijsen, R. T.; “ e n , U. A. T. J. Chnmmtop. 1992, 63@1-2), 201-12. Heo,0. S.; Suh,J. K. Anal. Sc/. Techno/. 1990, 39,355-65. A M . A.; &ob, K.; Marlanl, C. Fen W s . Techmi. 1993, 95(5), 17680. BIBdermam,M.; &ob. K.; Froehkh, D.;Meier, W. 2.Lebensm.-Unters. F m c h . 1992, 795(5), 409-16. ChaPPek C. G.; Creaser, C. S.; Shepherd, M. J. J. Chnmatqr. 1092, 628(2), 223-30. De Paoli, M.; Barbha, M. T.; Mondini, R.; Peuoni, A.: Valentino, A.; &Ob. K. J. chnxnatop. 1992, 62&1), 145-50. Kelly, G. W.: Bartle,K. D.; Clifford, A. A.; Robinson, R. E. J. MghResolut. C W O m w . 1992, lq8), 526-30.

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Analytical Chemistry, Vol. 66, No. 12, June 15, 1994

(E43)

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QC DETECTION METHODS

Hill, H. H.; McMinn, D. 0. I n U6tstus fw CapWty chromstogvsqphy; HM, H. H., McMlnn. D. G., EQ.; John Wiley & Sons, Inc.: New York, 1992; Chapter 1. HWI, H. H.; McMlnn, D. G. In Detectors fw C a p b y Ctwvmntob*ephyr HI, H. H., W n n , D. G., EQ.; John Wlby & Son8, Inc.: New York, 199% Chapter 2. Staby, A.; ‘BorcMensen. C.; Mdlerup, J.; Jensen, E., J. Chromatop. 1993, M I ) , 221-32. M a l , M.; Palyka, I.; Moinar-Ped. I. J. Chmnarogv.&I. 1992,sqll). 148-52. .Kuhn, L. A. plet. M.F M . 1992, 79(10). 16-7. Blanco,D.G.;CanQa,J. S.;Dcnnlnguez,A.; I@esles,M. J.;QuWen, M.D. J. Chmmaw. 1992, 607(2), 295-302. SkFi. A.; Verge, G. Eur. Pat. Appi. EP 538,678, 1993, Patterson, P. L. CtwvmnISSS, 36, 225-33. Jewry, D. J.; Stack, G. C.; W , H. M. Am. W .wO2,2416), 48. Tsujlno, Y.; Kuwata, K. J. Chroma-. 1993, 812(1-2), 383-8. Woods, W. A.; Brown, P. 0.; Sogut, 0. S. h e . Inst. iMech. €n@, I M C E Conf. 1992, 193-203. RatRbclr, W. Ger. 0th.DE 4,138,080, 1993. Ratfisch. W. Qer. Wen. DE 4,136,413, 1993. RatRaCh, W. Qer. Wen. DE 4,138,660, 1993. RatRech, W. Qer. Otten. DE 4,138,660, 1993. Ratthch, W. Qer. Wen. DE 4,136,412, 1993. RatRaCh, W. Ger. Offen. DE 4,131,412, 1993. Ramsey. R. S.; Anbawes, F. F. I n Detectors fw capllbry Chrome~@y;HWI,H.H.,MoMkm,D.G.,EQ.;JohnWlleydSone,Inc.: New York. 1992; Chapter 3. Wentwath, W. E.; Vasnin, S. V.; Steams, S. D.; Meyer. C. J. m 1992, 345-8). 219-25. Driscdl, J. N. I n Detectors fw G@”Y Chrometopaphy; HUI, H. H., MoMkm.D.G.,Eds.;JohnWlley&Sons, Inc.: NewYork, 1992Chapter 4. Lu, M.; Wang, Y.; Jing, S.; Chen. 2. Huen/&?gHuamre1992, 11(2), 21-5. bsa, J.; Siiwke, I.; Kms, A,; Berskl, M.;Cygank, S. Poi. PL 154,924, 1991. YamadamS. Anal. chkn.Acta 1992, 261(1), 1-6. Smlth, E. W.; Pstruccl, G. A.; Badini, R. 0.; Wlnefordneir, J. D. Inst. p h 9 . Cont. W.1992. No. 128, 309-12. Patterson, P. L. I n Detectors fw CapWty Chromatobwephy; Hill, H. H., McMlnn, D. G., Eds.; John Wlley & Sons. Inc.: New York, 1992;Chapter 7. Tereda. M.; SNnOzuka, T.; Yasuda, M.: Yanaglda, J.; Wakasugi, C. -U 1992. 7q2), 142-3. Sew, Y.; Tsunoda, N.; Ohta, H.; Shhrohara, T. Anal. Chin?.Acta 1099, 278(2), 247-59. Kageua, M.;Fujwara, Y.; Hare, K.; Hleda. Y.; Kashimws, S. & c h W u 1992, lq2), 144-5. HII. ; Fuji, T.; Arimoto, H. I n Detectors fw C a p h y Ct~mmphy H. H., McMlnn, D. G., Eds.; John Wlley & Sons, Inc.: New York, 1992 Chapter 8. Ham,H.; Yamamto, 8.;Iwata, M.;Takadame,E.; Yamada,T.; Suuki, 0. J. chromatog: 1992, 579(2), 247-52. Hattd, H.; Yamamoto, S.; Iwata, M.; Tqakadrlma, E.; Yamada, T.; SUrUki, 0.J. 1092, 581(2), 213-8. Hattorl, H.; Suzukl, 0.; Seno. H.; Yamada, T. HochucWu 1993. 11(1), 31-8. m u d , E. P. I n Detectors for Caplkwy chromemphx Hili, H. H., McMnn,D. G., Eds.; John Wileyb Sons, Inc.: NewYork, 1992 Chapter 5. Bailey, E.; EI’OOkS, A. (3. F. MWOChkn. Acta 1992, 109(1-4). 1219. Benljnen. J. H.; Meenhorst, P. L.; Van Gib, R.; Hazelager, W. A.; Koks. c. H. W.; Underberg, W. J. M. J. phaftn. M.AMI. 1992, 7q4), 315. Hen, C.; Eumbieton, M.; Lao, D. T. W.; Benet, L. 2. J. ChKXnetogr. 1992. 579(2), 237-45. Osato, I.Jpn. Kokal Tokkyo Koho JP 04,303,759, 1992. Wentwath, W. E.; D’Sa, E. D.; Cai, H.; Steams,S. J. Wnvmetcgr. Scl. 1992, 3@12),478-85. Hill, H. H.; W n n , D.G. I n Detectors for Cap&ty Chwnato6waphyr Hill, H. H., McMinn, D. G., Eds.; John Wiby i Sons. Inc.: New York. 1992 ChaDtW 12. Atklnson, D. A,; HHI, H. H.; Shuk, T. D. J. Chnmatogr., Biomed. Appl. 1999, ei7(2), 173-9. Karpas, 2.;Wang, Y.-F.; Elceman, G. A. Anal. W m . Acta 1993,282(1), 19-31. TaNir, E. E.; Hill, H. H. Fresenlus’J. Anal. Chem. 1992, 34410-11). 453-9. LeWigham. K.; Marsha#, A. &It. UK Pat. Appl. QC 2,262,990, 1993. Snyder, A. P.; Harden, C. S.; Bmteln, A. H.; Kkn, M. G.: Arnold, N.S.; Meuzelaar. H. L. C. Am. Lab. 1092, 21(15), 328. Snyder, A. P.;Harden, C. S.; BrHhh, A. H.; Kim M. G. Amokl, N.S.; Meuzelaar, H. L. C. Anal. Chem. 1998, 65(3), 299-306. Wentworth, W. E.; Steams, S. D. PCT Int. Appl. WO 92 15,874,1992. Yu, A.; Xu, W.; Wang. F.; Wang, X.: Liu, Y. Jin, Q. Chem. Res. Chh. Univ. 1991. 7(4), 243-4. Yu, A.; Wang. X.; Jin, 0. Gaaodeng Xwxlao H w w Xuebao 1002. 7312). 1533-5.

mw.

Yu,A.; Wang,X.;Yang, W.; J1n.Q.; Wang, F. FenxlHuaxuel993,21(6), 736-9. Kadkhodayan, B.; Turler, A.; Gregorlch. K. E.; Nurmla. M. J.; Lee. D. M.; Hoffman, D. C. Nwl. Inshum. Methodsphys. Res., Sect. A 1992, A317(1-2), 254-61. Markham, D. A.; Langvardt, P. W. U.S.Patent US 5,242,471, 1992. Uden. P. c. I n Detectom for Capll&ty chromatogaphy; Hill, H. H., McMlnn, D. G.,Eds.; John Wiley& Sons, Inc.: New York. 1992; Chapter 10. Qulmby, B. D.; Giarrocco, V.; Suiihran, J. J.; McCleary, D. A. J. H@h Resolut. Chromatog. 1992, 15(11), 705-9. Koman, J. J.; Lukco, R. 0. J. Chromatop. W. 1093, 31(3), 88-94. Kovacic, N.; Ramus, T. L. J. Anal. At. Spectrom. 1992, 7(6), 999-1005. Davld, F.; Sandra, P. Analusis 1992, 20(8), M53-4. Ceulemans, M.; Szpunarloblnska, J.; Dlrkx, W. M. R.; Loblnskl. R.; Adams, F. C. Int. J. Envkon. Anal. Chem. 1993, 5al-4). 113-25. Lansens, P.; Meuleman, C.; Lalno,C. C.; Baeyens, W. Appl. Organomet. Chem, 1993, 7(1). 45-51. Loblnskl, R.; Adams, F. C. Trends Anal. Chem. 1093, 12(2), 41-9. Llu, Y.; Lopez-Avlla, V.; Alcaraz, M.; Beckert, W. F.; Helthmar, E.M. J. ChrmtOgf. SCl. 1993, 31(8), 310-6. Park, Y. J.; Yoo, H. S.; Lee, N. S. Bull. Korean Chem. Soc. 1992, 13(4), 349-5 1. Yu, A.; Jln, a. Jllln Daxue Zlran Kexue Xuebao 1991, (4), 99-102. Birch, M. E. Anal. Chkn. Acta 1993, 282(2), 451-8. Tomberg, W. L.; Dlck-Hennes, E.; Buenlng-Pfaue, H. J. H/gh Resolut. C h m m t q . 1992, 15(4), 279-80. Caetano, M.; Goldlng, R. E.; Key, E. A. J. Anal. At. Spectrom. 1992, IS), 1007-11. Ahrarez-Bolainez, R. M.; Boss, C. 8. Anal. Chim. Acta 1992. 269(1), 89-97. Pedersen-Bkrgaard, S.; Grelbrokk, T. J. High Resokrt. Chromatcgr, 1992, lqlO), 677-81. Pedersen-Bjergaard,S.; Grelbrokk, T. Anal. Chem. 1993,65(15), 19982002. Vasnln. S. V.; Wentworth, W. E.; Stearns, S. D.; Meyer, C. J. ChfOmatOgrephle 1992, 345-8), 226-34. Sun, X. Y.; Mllller B.; Aue, W. A. Can. J. Chem. 1992, 7q4), 1129-42. Qulmby, B. D.; Dryden, P. C.; Sullhran, J. J. Synth. Appl. Isot. Labelhi Compd. 1991, Roc. Int. Symp., 4th 1991 1992, 128-32. Hutte, R. S.; Ray, J. D. I n Detectors forCapll&ryChromatogrephy;Hill, H. H., McMlnn. D. G..Eds.; John Wllev & Sons. Inc.: New York. 1992: Chapter 9. Verga. G. R. J. H@h Resolut. Chromatcgr. 1992, l5(4), 235-7. Shlbata, S. Jpn. Kokai Tokkyo Koho, Patent No. 05 87,737, 1993. Cheskls, S.; Atar, E.; Amlrav, A. Anal. Chem. 1993, 65(5), 539-55. Flddler, W.; Doerr, R. C. J. AOAC Int. 1993, 7@3), 578-81. Been. S. M.; Myung. K.; Fujlnarl, E. M. Dev. Food. Scl. 1993, 65-73. Hayakawa, K.; Butoh, M.; Mlyazakl, M. Anal. C h h . Acta 1992,26@2), 251-6. Sye, W. F.; Zhao, 2. X.; Lee, M. L. Chromatograph& 1992, 3x111112), 507-13. Shearer, R. L. Anal. Chem. 1992, 64(18), 2192-6. Shearer, R. L.; Pooh E. B.; Nowalk, J. B. J. Chromatog. Scl. 1993, 31(3), 82-7. Dlrkx, W. M. R.; Adams, F. C. MlkroChlm. Acta 1992, 109(1-4), 79-81. Bornhop, D. J.; Verge, G. R. Trends Anal. Chem. 1992, 11(5), 194-9. Hayhurst, J. S.; Driscoil, J. N. Anal. Roc. 1993, 3q2), 90-2. Gurka, D. F. In Detectors for Caplliary Chromatography; Hili, H. H., McMlnn, D. G.,Eds.; John Wtley& Sons, Inc.: New York, 1992; Chapter ii

Hei,R. C. I n Detectorstorcapwychmtoqa~y;HIM,H. H., McMlnn, D. Q., Eds.; John Wiley & Sons, Inc.: New York, 1992; Chapter 6. Barbour, C. J. Unhrersity of NorthCarollna Dlssertation, Unhr. Microfilms Int. Order No. DA9135225; Diss. Abstr. Int. B 1992, 52(7), 3569. Kabasawa, A.; Nlshina, T.; Matsue, T.; Uchida, I. Denkl Kagaku oyobl KObyO Buts& DaQRkU 1993, 61(7), 825-6. Lu, J.; Tlan, C. J. Electraenal. Chem. 1993, 345(1-2), 27-42. Lechner-Fish. T. J.; Cordill, L. D.; Cooper, 0.W.; Combs, 0. L. Am. L8b. 1992, 24(11), 28. Zakharova, L. V. Zavod. Lab. 1992, 58(4), 9-11. Watson, G.;Horton, W.; Staples. E. Ultrason. Symp. Roc. 1992, 1, 305-9. Mecham, R. 1.; Buffham, B. A.; Mason, G. J. Chromatogr. Sci. 1992, 3ql l), 459-64. Mllller. B.; Sun, X. Y.; Aue, W. A. Anal. Chem. 1993. 65(2), 104-11. Kalpalnen, A.; Kostiainen, 0.;Rlekkola, M. L. J. MlwocdumnSep.1992, 4(3), 245-51. Kessels, H.; Hoogerwerf, W.; Llps, J. Analusis 1992, 20(8), M55-60. Kessels, H.; Hoogerwerf, W.; Llps, J. J. Chromatogr. Scl. 1992, 3q7),

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9A7-55

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Bicchi. C.; Frattinl, C.; Pellegrlno, 0.;Rubblo, P.;Raverdino, V.; Tsoupras, G. J. ChrOmatOgf. 1992, 609(1-2), 305-13. Dachs. J.; Bayona, F. M. M/kroChlm. Acta 1992, 709(1-4), Tolosa, I.; 87-91. (F100) Mlranda-Lopez,Rlta; Llbbey. Leonard M.; Watson, Barney T.; McDaniel. M. R. J. Food SC/. 1992, 57(4), 985. QAS CHROMATOaRAPHY/MASS SPECTROMETRY (GI) (02)

Roach, L.; Gullhaus, M. Org. Mas Spectrom. 1992, 27(10), 1071-6. Schuk, G.A.; Chamberlln, B. A.; Sweeley, C. C.; Watson, J. T.; Alison, J. J. ChrOmtW. 1992, 59q2), 329-39. (a)Bonln, M. A.; Ashley, D. L.; Cardlnail, F. L.; McCraw, J. M.; Patterson, D. G., Jr. J. Am. Soc.Mess Spsctrom. 1992, 3(8). 831-41. (a)Sahota. R. S.; Morgan, S. L. Anal. Chem. 1993, 65(1), 70-7.

Revill, A. T.; Carr. M. R.; Rowlend, S. J. J. Chromatog. 1992,589(1-2), 281-6. (G6) Elceman, 0. A.; Urquhart, N. S.; OConner, 0. A. J. Envkon. Qual. 1993, 22(1), 167-73. (G7) Klelntop, B. L.; Yost, R. A.; Abolln, C. R. J. Am. Soc. Mess Spectmn. 1892, 3(1), 85-8. (G8) Schlmmei, H.; Schmid, B.; Bacher, R.; Ballschmlter, K. Anal. Chem. 1993, 65(5), 640-4. (G9) D’Agostlno. P. A.; Porter, C. J. RapM Commun. h s s Spec-. 1992, e l l ) , 717-18. (G10) Olson, L. K.; Heltkemper. D. T.; Caruso. J. A. ACSSymp. Ser. 1992, No. 479, 288-308. (011) Robbat, A., Jr.; Llu, T. Y.; Abraham, B. M. Anal. Chem. 1992, 64(13), 1477-83. (012) Robbat, A., Jr.; Llu, T. Y.; Abraham, B. M. Anal. Chem. 1992. 64(4), 358-64. (G5)

QUALITATIVE AND QUANTITATIVE ANALYSIS

(H19) (H20) (H21) (H22) (H23) (H24) (H25) (H26) (H27) (H28) (H29) (H30) (H31) (H32) (H33) (H34) (H35) (H36) (H37) (H38) (H39)

Tande, T.; Brehrik, H.; Aasoldsen, T. J. Am. O/l Chem. Soc. 1992, 69(1l), 1124-30. Mlsra, R. K.; uthe,J. F.; Muslal, C. J. AnaNst 1992, 177(7), 1085-91. o w . Telllard. W. A.; McCarty, H. 8.; King, J. R. Organohalogen C 1990, 2, 303-6. Telllard, W. A.; McCarty, H. B.; Rlddlck, L. S. Chempherel993,27(13), 41-6. Pocklington, W. D. J. Am. OllChem. Soc. 1992, 69(8), 789-93. Franke, J. P.; Wljsbeek, J.; De Zeeauw, R. A. J. Forensic Scl. 1990, 3q4), 813-20. De Boer, J.; Duinker, J. C.; Calder, J. A.; Van der Mar, J. J. AOAC Int 1992, 75(6), 1054-62. Xu, 0.; Zhang, Y.; Lu, P. Sepu 1993, 11(2), 65-8. Jayatllaka, A.; Poole, C. F. J. Chromatogr..,Biomed. Appl. 1993.617(1), 19-27. Holzer, 0.; Bertsch, W.; Zhang, a. W. Anal. Chkn. Acta 1992,258(2), 225-35. @ob, R. L.; Barry, E. F.; Leeplpatplboon. S.; Ombaba, J. M.; Colon. L. A. J. ChfOmatOgf. SCl, 1992, 3q5),177-83. Scheuer, K. Chemom. Intell. h b . Syst. 1993, 19(2), 201-16. Dwenbeck. C.; Zinn, P. J. Chem. Inf. Comput. Sci. 1993,33(2), 21 1-9. Makino, M.; Kamlya, M.; Matsuihlta. H. Envkon. Int. 1993, l9(2), 20310. Snow, N. H.; McNalr, H. M. J. Chromatop. Scl. 1092, 3q7). 271-5. Jlmener, 8.; Tabera, J.; Hemandez, L. M.; Gonzalez,M. J. J. Chromatog. 1992, 607(2), 271-8. Lln, J. C. C.; Nagy, S.; Kllm, M. Food Chem. 1993, 47(3), 235-45. Narasimhan, S.; Rajalakshmi, D.; Chand, N. J. FoodQuel. 1992, 15(1), 67-83. Forcen, M.; Mulet, A.; Bera, A. J. Scl. FoodA@c. 1992, 6q2). 229-38. Francelln, R. A.; Gomlde, F. A. C.; Lancas. F. M. Chroma&” 1993, 35(3-4), 160-6. Plno, J.; Nuner de Vlllavlcencio, M.; Roncai, E. N m n g 1992, 38(3), 302-6. Sahota, R. S.; Morgan, S. L. Anal. Chem. 1992, 64(20), 2383-92. Singh, A. Anal. Chlm. Acta 1993, 277(2), 205-14. Gelser, F. 0.; Gok, C.; Kung, L., Jr.; Justlce, J. D.; Brown, B. L. J. Chometog. 1993, 63(1-2), 1-13. Mason, J. P.;Klrk, I.; Windsor, C. G.; Tipler, A,; Spragg, R. A.; Rendle, M. J. High Resolut. Chromatog. 1992, 15(8), 539-47. Hide, M.; Okuyama, S.; Mksui, T.; Mlnaml, Y.; Fujlmura, Y. ChroNltWfaPhia 1993, 35(9-12), 643-8. Lavine, B. K.; Stlne, A.; Mayfield, H. T. Anal. Chlm. Acta 1993, 277(2), 357-67. Klappa, S. A.; Long, G. R. Anal. Chlm. Acta 1992. 259(1), 89-93. Poole, C. F.; Kollle, T. 0.; Poole, S. K. Chromatographle 1992,34(5-8), 28 1-302. Helnzen, V. E. F.; Yunes, R. A. J. Chromatcgr. 1902, 598(2), 243-50. Arruda. A. C.; Helnren, V. E. F.; Yunes, R. A. J. C h m t c g r . 1992, 63q1-23, 251-6. KUpchlk, E. J. J. Chromatog. 1992, 63411-23, 233-40. Hassanl, A.; Meklatl, B. Y. Chromatogrephla 1992, 33(5-6), 267-71. Zenkevich, I.0.; Shchepanyak. L. M. Zh. Anal. Khh. 1992, 47(3), 507-13. KOkkO, M. J. ChfOmBtogr. 1992, 63q1-2), 231-49. Zhang, H.; Hu, 2. Chromatographie 1992, 3x11-12), 575-80. Skrbic, 8. D.; Cvejanov, J. D. Chrometographla 1992, 341-2), 83-4. Castello, G.;Motetti,P.; Vezzani, S. J. Chromatog. 1993,635(1), 10311. Mehran, M.; Cooper, W. J.; Golkar, N.; Nickelsen, M. 0.;MltHefhldt, E. R.; -,,eGuthrle, E.; Jennings, W. J. HighResolut. Chromatog. 1991, 14(1I), CII

I

*a-au.

Needham, M. D.; Jurs, P. C. Anal. Chim. Acta 1992,25&2), 183-98. Lokshln, A. Int. J. Mess Spectrom. Ion processes 1992. 12011-2). 117-27. Thomas, L. C.; Weichmann. W. J. Chromatog. 1991,587(2), 255-62. Thomas, L. C.; Welchmann. W. Ta&nta 1992, 39(3), 201-6. Herman, F. L. Anal. Chem. 1993, 65(8), 1023-7. Mlllier. B.; Sun, X. Y.; Aue. W. A. Anal. C h m . 1993, 65(2), 104-11. Molnar-Perl, I. J. CMomatogr. Scl. 1992, 341I), Morval, M.; Palyka, I.; 448-52. Eakln. P. A.; Failick, A. E.; Gerc, J. Chem. -1. 1992, lOl(1-2). 71-9.

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