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choice in the conversion of compounds for 1S0 analysis by mass spectrometry. BETTIE J. ... and nickel. W/LL/AM B. BARNETT, Perkin-Elmer Corp., Norwalk...
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A C BRIEFS Highlights of Articles in This Issue

Study of Electroplated Gold by Spark Source Mass Spectrometry Organic impurities present in hard gold electroplates appear as ions in the spark source mass spectrum with intensities 16 times higher than their bulk concentration. M. J. VASILE and D. L. MALM, Bell Telephone ries, Incorporated, Murray Hill, N.J.

Laborato-

Anal. Chem., 44, 650 (1972) Réévaluation of the Preparation of Organic Compounds for the Mass Spectrometric Analysis for Oxygen-18 Yields of carbon dioxide from pyrolyses of organic compounds indicate that stannic chloride is the sensitizer of choice in the conversion of compounds for 1S 0 analysis by mass spectrometry. BETTIE J. FONG, S. R. SMITH, and JOHN TANAKA, Department of Chemistry and Materials Science Institute, University of Connecticut, Storrs, Conn. 06268 Anal. Chem., 44, 655 (1972) Mass Spectrometric Isotope Ratio Measurements and Peak Area Integration Using the Peak-Switching Feature of the ΑΕΙ MS-902 A computerized system for isotope ratio measurements using the standard voltage peak-switching circuitry of the Α Ε Ι MS-902 mass spectometer is described, with applications to trace metal determinations as volatile chelates. Ν. Μ. FREW and T. L. ISENHOUR, Department of Chem­ istry, University of North Carolina, Chapel Hill, N.C. 27514 Anal. Chem., 44, 659 (1972) Isotopic Analysis of Chromium in Lunar Materials by Mass Spectrometry of the Trifluoroacetylacetonate An analysis for chromium in silicate rocks by mass spec­ trometry of the volatile trifluoroacetylacetonate is described. Chromium isotope ratios in Apollo 12 lunar materials, in­ cluding four crystalline rocks and two soil samples, are re­ ported, as are the chromium contents of several U.S.G.S. standards and lunar rocks. N. M. FREW, J. J. LEARY, and T. L. ISENHOUR, Depart­ ment of Chemistry, University of North Carolina, Chapel Hill, N.C. 27514 Anal Chem., 44, 665 (1972)

Heats of Immersion and Swelling of Cation Resins and Related Model Systems in Water and Nonaqueous Solvents Interactions between water or organic solvents and cation resins were studied b y calorimetric and microscopic tech­ niques. Macroreticular and microreticular cation resins, resins without charge sites, and a resin model compound were studied. ALAN D. WILKS and DONALD J. PIETRZYK, University of Iowa, Department of Chemistry, Iowa City, Iowa 52240 Anal. Chem., 44, 676 (1972) Apparatus for Supercritical Fluid Chromatography with Carbon Dioxide as the Mobile Phase An improved pressure-programmable pulseless pump with outputs up to 5000 psia, a high pressure ultraviolet detector cell, and a high pressure collection system have been de­ veloped. R. E. JENTOFT and T. H. GOUW, Chevron Research Com­ pany, Richmond, Calif. 94802 Anal. Chem., 44, 681 (1972)

Synergistic Effects in Ion Exchange in Mixed Solvents—Chloride Media The synergistic enhancement in the anion exchange of C o ( I I ) , C u ( I I ) , and U 0 2 ( I I ) in acetone-methanol-aqueous HC1 solutions has been elucidated from the absorption spec­ tral measurements in the solution and the resin. A. P. RAO and S. P. DUBEY, Chemistry Department, Institute of Technology, Delhi, New Delhi-29, India

Indian

Anal. Chem., 44, 686 (1972)

Chromatographic Separation of Molybdenum Using an Aliphatic α-Hydroxy Oxime Molybdenum(VI) is separated from other metal ions by column chromatography using an aliphatic α-hydroxy oxime as the stationary phase. The probable structure of the molybdenum complex is reported. JAMES S. FRITZ and DONALD R. BEUERMAN, Institute for Atomic Research and Department of Chemistry, Iowa State University, Ames, Iowa 50010 Anal. Chem., 44, 692 (1972)

Establishing Water Contents of Hydrogen Form Resins by Heats of Immersion Experimental steps in handling cation exchange resin and solvents in heats of immersion studies are evaluated. A method for measuring and controlling low level water con­ tents of resins is described. MERLIN D. GRIESER, ALAN D. WILKS, and DONALD J. PIETRZYK, University of Iowa, Department of Chemistry, Iowa City, Iowa 52240 Anal. Chem., 44, 671 (1972)

Acid Interferences in Atomic Absorption Spectrometry An air-acetylene flame, a single-slot burner head, and a flow spoiler help to minimize acid interferences in the atomic absorption determinations of copper, chromium, manganese, and nickel. W/LL/AM B. BARNETT, Perkin-Elmer Corp., Norwalk, Conn. 06852 Anal. Chem., 44, 695 (1972) ANALYTICAL CHEMISTRY, VOL. 44, NO. 4, APRIL 1972

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AC BRIEFS Double Modulation—Optical Scanning and Mechanical Chopping—in Atomic Absorption Spectrometry Using a Continuum Source

Electrochemistry of Substances Solubilized in Micelles. Polarography of Azobenzene in Aqueous Surfactant Solutions

A double modulated atomic absorption flame spectrometer with a continuum source is described. T h e response of the system agrees with predictions.

Aqueous solutions containing surfactant micelles which solubilize organic compounds provide a new medium for electrochemical studies. The polarography of azobenzene has been investigated to illustrate the applicability of this solvent system.

R. C. ELSER and J. D. WINEFORDNER, Department of Chemistry, University of Florida, Gainesville, Fla. 32601 Anal. Chem., 44, 698 (1972) Flame Detection Method for Determining Organic Carbon in Water A rapid thermal analysis technique is described for determining organic carbon in water down to about 0.2 ppm and differentiating the contaminants according to volatility. F. T. EGGERTSEN and F. H. STROSS, Shell Company, Emeryville, Calif.

Development

Anal. Chem., 44, 709 (1972) Electrochemistry of Phenazine at a Platinum Electrode in Aprotic Solvents Cyclic voltammctry, chronopotentiometry, and controlled potential electrolysis have been used to determine the stoichiometry, thermodynamics, and kinetics of the electron transfer processes for phenazine in dimethylsulfoxidc, dimethylformamide, and acetonitrile. DONALD T. SAWYER and RALPH Y. KOMAI, Department of Chemistry, University of California, Riverside, Calif. 92502 Anal. Chem., 44, 715 (1972)

Comparative Study of a Wide Variety of Polarographic Techniques with Multifunctional Instrumentation Using multifunctional polarographic instrumentation, a critical comparison of a large number of dc, ac, pulse, and inverse polarographic techniques is reported, with emphasis on detection limits and suitability for routine analysis. A. M. BOND, Department of Inorganic Chemistry, University of Melbourne, Parkville, 3052, Victoria, Australia, and D. R. CANTERFORD, Department of Physical Chemistry, University of Me/bourne, Parkville, 3052, Victoria, Australia Anal. Chem., 44, 721 (1972)

Theoretical and Experimental Evaluation of Multielement Analysis by Fundamental Harmonic Alternating Current Polarography Theoretical considerations of direct simultaneous determination of species with similar half-wave potentials by fundamental harmonic alternating current polarography are given. Excellent agreement with experiment is observed. A. M. BOND and J. H. CANTERFORD, Department of Inorganic Chemistry, University of Melbourne, Parkville, 3052, Victoria, Australia Anal. Chem., 44, 732 (1972)

PAMELA G. WESTMORELAND, R. A. DAY, JR., and A. L. UNDERWOOD, Department of Chemistry, Emory University, Atlanta, Ga., 30322 Anal. Chem., 44, 737 (1972) Titration Reactions of Alkylaluminum Compounds Using Phenazine Indicator T h e pyridine titration of alkylaluminum compounds using phenazine indicator has been investigated and found to involve both complexation and reduction reactions. GEORGE W. HEUNISCH, Research and Development Department, Continental Oil Company, Ponca City, Okla. 74601 Anal. Chem., 44, 741 (1972) Voltammetric Behavior of Nitrite Ion on Platinum in Neutral and Weakly Acidic Media The electrooxidation of N 0 2 - to N 0 3 _ on platinum in neutral and weakly acidic aqueous media proceeds via the reversible electrode reaction NCV ^ N 0 2 -f- e, followed by the homogeneous disproportionation of N 0 2 ; 2 N 0 2 + H 2 0 - » N 0 2 - + N O » - + 2H + . ROLANDO University PERGOLA Chemistry Italy

GUIDELLI, Institute of Analytical Chemistry, of Florence, Florence, Italy, and FRANCESCO and GIORGIO RASPI, Institute of Analytical and Electrochemistry, University of Pisa, Pisa, Anal. Chem., 44, 745 (1972)

Study of Effects of Neutral Inorganic Salts on Potentiometric Titration Curves of Weak Bases in Nonaqueous Solvents LiClOi, Mg(C10 4 ) 2 , and Lil enhance the potentiometric end point break for the titration of weak bases in acetone, methyl isobutyl ketone, and 2-butanone. Caffeine (Kb = 10 la ") can be titrated in acetone containing ZM lithium perchlorate. W. LYNN SCHERTZ and GARY D. CHRISTIAN, Department of Chemistry, University of Kentucky, Lexington, Ky. 40506 Anal. Chem., 44, 755 (1972) On the Voltammetric Behavior of the Carbon DioxideOxygen-Carbonate System in Molten Alkali Nitrates The voltammetric behavior of the system C02,0 2 /C0 3 !> " in molten alkali nitrates and the possibility of utilizing the R D E voltammetric technique to detect CO», 0 2 and CCV" present together in molten solutions arc explored and discussed. PIER GIORGIO ZAMBONIN, Istituto di Chimica Via Amendola 173-Universita', Bari, Italy

Analitica,

Anal. Chem., 44, 763 (1972) ANALYTICAL CHEMISTRY, VOL. 44, NO. 4, APRIL 1972 ·

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AC BRIEFS Simple Analog System for Simultaneous Kinetic Analysis

Indirect Spectrophotometry Determination of Oxalate Using Uranium and 4-(2-Pyridylazo)resorcinol

An analog system for automalic graphical presentation of simultaneous kinetic analysis data is presented. Application of the system is illustrated for rare earth mixtures.

Oxalate is determined indirectly at the ppm level via the diminishment in absorbance effected by oxalate on the red uranium(IV)-4-(2-pyridylazo) resorcinol complex.

JAMES B. WORTHINGTON and HARRY L. PARDUE, Department ot Chemistry, Purdue University, Lafayette, Ind. 47907 Anal. Chem., 44, 767 (1972)

ROBERT E. NEAS and JOHN C. GUYON, Department of Chemistry, University of Missouri, Columbia, Mo. 65201 Anal. Chem., 44, 799 (1972) Homogeneous Liquid—Liquid Extraction Method. Extraction of Iron(lll) Thenoyltrifluoroacetonate by Propylene Carbonate

Spectral Evaluation of a Sealed Helium Discharge Lamp for Studies in Photoelectron Spectroscopy The use of thin-film aluminum windows in constructing a sealed resonance lamp for photoelectron spectroscopy studies is described. JAMES A. KINSINGER, W/LL/AM L. STEBBINGS, RICHARD A. VALENZI, and JAMES W. TAYLOR, Department of Chemistry, University of Wisconsin, Madison, Wis. 53706 Anal. Chem., 44, 773 (1972)

The extraction rate of iron(III) thenoyltrifluoroacetonate known as a very slow one was accelerated remarkably by using a new homogeneous liquid—liquid extraction method. KATSUO MURATA, YU YOKOYAMA, and SHIGERO IKEDA, Department of Chemistry, Faculty of Science, Osaka University, Toyonaka, Osaka, Japan Anal. Chem., 44, 805 (1972) Medium Effects for Single Ions in Acetonitrile and Ethanol—Water Solvents Based on ReferenceElectrolyte Assumptions

Pulse Overlap Effects on Linearity and Signal-to-Noise Ratio in Photon Counting Systems A mathematical treatment reveals that the linearity and signal-to-noisc ratio obtained for a photon counting system are dependent on the discriminator level and the magnitude and source of the dead time. J. D. INGLE, JR., and S. R. CROUCH, Department of Chemistry, Michigan State University, East Lansing, Mich. 48823 Anal. Chem., 44, 777 (1972)

Medium effects of ions in acetonitrile and ethanol-water solvents based on the tetraphenylarsonium or tetraphenylphosphonium tetraphenylborate assumptions are identical, but differ somewhat from those based on the triisoamyl-rebutylammonium tetraphenylborate assumption. OREST POPOVYCH, ALLAN GIBOFSKY, and DAVID H. BERNE, Department of Chemistry Brooklyn College of the City University of New York, Brooklyn, N.Y. 11210 Anal. Chem., 44, 811 (1972)

Critical Comparison of Photon Counting and Direct Current Measurement Techniques for Quantitative Spectrometric Methods Signal-to-noise ratio theory is used to compare photon counting and dc techniques for analytical atomic and molecular spectrometry. Criteria for choosing between the techniques are established. J. D. INGLE, JR., and S. R. CROUCH, Department of Chemistry, Michigan State University, East Lansing, Mich. 48823 Anal. Chem., 44, 785 (1972)

Solubilities and Medium Effects of Tetraphenylgermane, Tetraphenylmethane, and Tetraphenylsilane in Acetonitrile, Methanol, and Some EthanolWater Solvents The medium effects of tetraaryl and tetraalkyl "reference ions" are generally well approximated by the sum of a Born electrostatic term and a medium effect for an uncharged tetraphcnyl compound. DAVID H. BERNE and OREST POPOVYCH, Department of Chemistry, Brooklyn College of the City University of New York, Brooklyn, N.Y. 11210 Anal. Chem., 44, 817 (1972)

Automated Colorimetric Determination of Penicillin in Fermentation Samples Using a Molybdoarsenic Acid-Mercuric Chloride Reagent

Influence of Acidity on the Reaction of Ninhydrin with Amino Acids

An automated ultramicro procedure for the determination of penicillin V and G affords the following advantages: high specificity, accuracy, and precision (M = 8764, S% = 0.9) ; increased speed of analysis; and high sensitivity.

The influence of acidity on color production in the reaction of ninhydrin with amino acids has been elucidated. A mechanistic explanation is offered for the existence of optimal p H values.

KAJ ANDRÉ HOLM, Novo Terapeutisk Laboratorium Ndr. Fasanvej 215, 2200 Copenhagen N, Denmark

PAUL J. LAMOTHE and PATRICK G. McCORMICK, Department of Chemistry, Marquette University, Milwaukee, Wis. 53233 Anal. Chem., 44, 821 (1972)

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Anal. Chem., 44, 795 (1972)

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Determination of Chain Branching in Epoxy Resins by Nuclear Magnetic Resonance Spectrometry

Notes A Swept Electron Beam Rapid Scan Spectrophotometer—Some Qualitative Aspects An application of high speed video technology to rapid scan spectrophotometry is described. The system is capable of up to sixty spectra per second, and its linearity character­ istics are evaluated. The device requires no moving me­ chanical parts. R. E. SANTINI, M. J. MILANO, H. L. PARDUE, and D. W. MARGERUM, Department of Chemistry, Purdue University, Lafayette, Ind. 47907 Anal. Chem., 44, 826

(1972)

Analysis of Surface Oxidized Wool Fiber by X-Ray Electron Spectrometry Corona discharge and low temperature discharge treatment of wool were investigated as a method of improving the surface properties. MERLE M. M/LLARD, Western Marketing and Nutrition Re­ search Division, Agricu/tura/ Research Service, U.S. De­ partment of Agriculture, Berkeley, Calif. 94710 Anal. Chem., 44, 828

(1972)

X-Ray Photoelectron Spectrometry of Platinum Compounds X-ray photoelectron spectrometry has been used to char­ acterize a number of platinum compounds. The effect of oxidation state and ligand character are clearly seen in P t 4f7/2 binding energies. W. M. R/GGS, Central Research Department, E. I. du Pont de Nemours and Company, Wilmington, Del. 19898 Anai. Chem., 44, 830

(1972)

An Examination of the Exchange of Deuterium from Deuterium Oxide in Carbon Tetrachloride Solution with Hydrogen in Glass Using Infrared Spectrometry The infrared absorbance of H O D is used to measure the rate of exchange of deuterium from D 2 0 (or hydrogen from H 2 0 ) in CCL solution with hydrogen (or deuterium) in glass. PAUL K. GLASOE and CHARLES N. BUSH, Wittenberg Uni­ versity, Springfield, Ohio 45501 Anal. Chem., 44, 833 (1972) Indirect Spectrophotometric Determination of Nanomole Quantities of Oxiranes

Trichloroacetyl isocyanate reacts rapidly with hydroxyls producing a downfield shift of associated methine proton absorption in N M R spectra. Peak area comparisons can be utilized to calculate chain branching in bisphenol-A epoxy resins. H. D. MAK and M. G. ROGERS, Research and Development Laboratory, Dow Chemical of Canada, Limited, Sarnia, On­ tario, Canada Anal. Chem., 44, 837 (1972)

Multielement Neutron Activation Analysis of Biological Material Using Chemical Group Separations and High Resolution Gamma Spectrometry A method for the determination of up to 31 elements in a variety of biological specimens is described. G. H. MORRISON and Ν. Μ. POTTER, Department of Chem­ istry, Cornell University, Ithaca, N.Y. 14850 Anal. Chem., 44, 839

(1972)

Utility of the Separated Air/Acetylene Flame in Atomic Fluorescence Spectrometry Detection limits are presented for 22 elements determined by atomic fluorescence spectrometry in an air/acetylene flame. Flame separation with argon improves detection limits by between 1 and 4 χ . R. F. BROWNER, Department of Chemistry, Imperial Col­ lege of Science and Technology, London S.W. 7, U.K., and D. C. MANNING, The Perkin-Elmer Corporation, Norwalk, Conn. 06852 Anal. Chem., 44, 843

(1972)

Non-Aqueous Acid-Base Properties of Sodium Tetraphenylboron Sodium tetraphenylboron can be titrated quantitatively with tetra-n-butyl-ammonium hydroxide in a variety of solvents. The equivalence point is detected either potentiometrically or conductometrically. RICHARD E. JENSEN and PAMELA S. ROIGER, Depart­ ment of Chemistry, Gustavus Adolphus College, St. Peter, Minn. 56082 Anal. Chem., 44, 846 (1972)

Determination of Sodium Dodecyl Sulfate in the Presence of Lauryl Alcohol

An indirect spectrophotometric method has been developed to determine epoxides in nanomole quantities. The epoxide ring is converted to carbonyls by oxidation with sulfuric acid, water, and periodic acid. The periodate-iodate concentra­ tion is measured as the starch tri-iodide complex.

Titration of sodium dodecyl sulfate with cetyl pyridinium chloride is shown to be feasible both above and below the critical micelle concentration irrespective of the presence or absence of lauryl alcohol.

H. EDWARD MISHMASH and CLIFTON E. MELOAN, De­ partment of Chemistry, Kansas State University, Man­ hattan, Kan. 66502

ROBERT D. VOLD and KASHMIR/ L. MITTAL, Department of Chemistry, University of Southern California, Los An­ geles, Calif. 90007

Anal. Chem., 44, 835

(1972)

Anal. Chem., 44, 849 ANALYTICAL CHEMISTRY, VOL. 44, NO. 4, APRIL 1972

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AC Use of Metal Tungsten Bronze Electrodes in Chemical Analysis Sodium tungsten bronzes, N a x W 0 3 , were found to function as indicating electrodes for pH, pMetal, particularly Ag(I) and H g ( I I ) , and p 0 2 , and to follow potential changes in acidbase and redox titrations. M. A. WECHTER, H. R. SHANKS, G. CARTER, G. M. EBERT, R. GUGLIELMINO, and A. F. VOIGT, Institute for Atomic Research and Departments of Chemistry and Physics, Iowa State University, Ames, Iowa Anal. Chem., 44, 850

Saltzman Method for Determination of Low Concentrations of Oxides of Nitrogen in Automotive Exhaust The Saltzman method has been modified to analyze for low concentrations of oxides of nitrogen with accuracy and precision ranging up to 3 per cent. G. E. FISHER and D. E. BECKNELL, Scientific Research Staff, Ford Motor Company, Dearborn, Mich. 48121 Anal. Chem., 44, 863 (1972)

(1972)

Role of Solvent Extraction Parameters in Liquid Membrane Ion Selective Electrodes

Estimation of the Equivalent Weights of Celluloses

Distribution equilibria of tetrahexylammonium salts including the iodide and 19 organic anions have been determined. The equilibrium constants quantitatively account for the interferences of these ions with liquid membrane ion-selective electrodes. HELEN J. JAMES, GARY P. CARMACK, and HENRY FREISER, Department of Chemistry, University of Arizona, Tucson, Ariz. 85721 Anal. Chem., 44, 853

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Equivalent weights of cellulose specimens were determined using the Kiliani reaction and were observed to range from about 23,000 to 200,000. VERNON L. FRAMPTON, Basic Cotton Research Laboratory, The University of Texas, Austin, Texas Anal. Chem., 44, 866 (1972)

(1972)

Coated Wire Ion Selective Electrodes Ion selective electrodes for a number of inorganic and organic anions have been prepared in a coated wire configuration. The response characteristics and selectivity parameters of the coated wire electrodes compare favorably with those of the more conventional barrel type electrode. HELEN J. JAMES, GARY P. CARMACK, and HENRY FREISER, Department of Chemistry, University of Arizona, Tucson, Ariz. 85721 Anal. Chem., 44, 856 (1972)

Determination of Submicrogram Quantities of Mercury by the Coulometric—lodimetric Titration of Cyanide Produced in a Ligand-Exchange Reaction Nanogram quantities of mercury(II) have been determined by coupling a lieiuid-exchange reaction with constant-current coulometry. Test conditions and interferences have also been investigated. TIMOTHY J. ROHM, HENRY C. NIPPER, and WILLIAM C. PURDY, Department of Chemistry, University of Maryland, College Park, Md. 20742 Anal. Chem., 44, 869 (1972)

Separation of Fluoride and Chloride by Solvent Extraction Using Triphenylantimony(V) Derivatives Chloride and fluoride separation from aqueous complex solutions has been obtained by solvent extraction using triphenylantimony(V) halide formation. Fluoride separation is better than 99% in almost all tested media. HENRY CHERMETTE, CLAUDE MARTELET, DENISE SAND/NO, and JEAN TOUSSET, Institut de Physique Nucléaire, Université Claude Bernard de Lyon; (Institut de Physique Nucléaire et de Physique des Particules) 43, Bd du 11 novembre 1918, 69-Villeurbanne, France

Determination of Absorptivities and Ligand Association Numbers of Carbanion Salts A simple titration procedure was devised to obtain reliable results at carbanion concentrations as low as 10"5 M. LUDVIK AMBROZ, KAM-HAN WONG, and JOHANNES SMID, Chemistry Department, State University of New York College of Forestry, Syracuse, N.Y. 13210

Anal. Chem., 44, 857 (1972)

Anal. Chem., 44, 872 (1972)

Improvements in the Determination of Sulfur Hexafluoride for Use as a Meteorological Tracer Electron absorption detection techniques have been employed to determine concentrations of SF 6 to approximately one part in 1013. Oxygen interference was eliminated by the use of a 5A molecular sieve column to elute the SFo prior to the major components of air. P. G. SIMMONDS, G. R. SHOEMAKE, and J. E. LOVELOCK, International Science Consultants, 5200 Palm Drive, La Canada, Calif. 91011, and H. C. LORD, Environmental Data Corporation, 608 Fig Avenue, Monrovia, Calif. 91016 Anal. Chem., 44, 860 (1972)

Correspondence Diffusion Barrier Model for the Cyanide Ion Selective Electrode DENNIS H. EVANS, Department of Chemistry, of Wisconsin, Madison, Wis. 53706

University

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A C BRIEFS Separation of Tellurium from Selenium and Other Fission Products by Precipitation with 1,10-Phenanthroline R. R. R/CKARD and E. I. WYATT, Oak Ridge National Laboratory, Post Office Box X, Oak Ridge, Tenn. 37831 Anal. Chem., 44, 877 (1972) Criterion for Judging the Acceptability of Analytical Methods KAREL ECKSCHLAGER, Institute of Inorganic Chemistry, Czechoslovak Academy of Sciences, Prague, Czechoslovakia Anal. Chem., 44, 878 (1972) Aromatic Hydroxylation as an Analytical Reaction KENNETH A. CONNORS and KENNETH S. ALBERT, School of Pharmacy, University of Wisconsin, Madison, Wis. 53706 Anal. Chem., 44, 879 (1972) Nuclear Magnetic Resonance Determination of tert-Butyl Hydroperoxide WILLIAM B. SMITH, Department of Chemistry, Christian University, Fort Worth, Texas 76129

Texas

Anal. Chem., 44, 881 (1972)

Aids for Analytical Chemists Simple Apparatus for Performing Reactions and Filtration Operations in the Absence of Air R. DONALD SPENCER, Carnegie-Mellon University, Mellon Institute, Pittsburgh, Pa. 15213 Anal. Chem., 44, 882 (1972) Simple Device for Introduction of Mass Calibrant into a Gas Chromatograph-Mass Spectrometer System D. M. SCHOENGOLD and W. H. STEWART, Sun Oil Company, Marcus Hook, Pa. 19601 Anal. Chem., 44, 884 (1972) Electrolytic Calibration Technique for Dissolved Nitrogen Determination in Seawater by On-Stream Stripping Gas Chromatography L. P. ATKINSON, Department of Oceanography, Dalhousie University, Halifax, Nova Scotia, Canada Anal. Chem., 44, 885 (1972) Rapid Technique for Dissolution of Nitrides DEAN H. B0LLMAN, U.S. Department of the Interior, Bureau of Mines, Albany Metallurgy Research Center, Albany, Ore. 97321 Anal. Chem., 44, 887 (1972) Simple Equation for Linearization of Data in Differential Scanning Calorimetric Purity Determinations DAVID L. S0NDACK, Eli Lilly and Company, Indianapolis, Ind. 46206 Anal. Chem., 44, 888 (1972)

Nester/Faust High-Purity Separations: Distillation or Preparative Chromatography? W e have the answer. Two Hundred Theoretical Plate Distillation System. The NFA-200, Adiabatic Teflon Spinning Band distillation column is the product of over fifteen years development and improvement in the science of spinning band fractionation. High purity separations of materials with boiling point differences as small as 0.2°C can be made with rapid throughputs at pressures as low as .005 mm Hg, with only .5 ml holdup. Automatic accessories such as auto reflux control, pot temperature control and head temperature deviation monitor allow unmatched ease of operation with minimal operator time expenditures.

We have the answer. Automatic Preparative Chromatograph The Model 750 Preparative Gas Chromatograph allows automatic injection and collection of samples of from 0.2 to 20 ml. The high resolving power of the Biwall annular columns permits preparative size samples with analytical resolution, and the unique peak selection computer provides automatic unattended collection of any fraction or shoulder. Other outstanding features include absolutely repeatable temperature programming and injection, 450°C capability and high capacity oven (up to 75' of % inch column). Options available include Flame Ionization Detector, Electrostatic Precipitator, and all-glass system. For help with your separations problems and complete descriptions, specifications and applications of the NFA-200 and Prepkromatic 750 contact Nester/Faust Mfg. Corp. at Box 565, Newark, Delaware 19711, Phone: (302) 737-6330. N E S T E R / FAUST

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ANALYTICAL CHEMISTRY, VOL. 44, NO. 4, APRIL 1972

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