AC BRIEFS

The solid form of the ureide of L-valine isopropyl ester was shown to give ... particle and 18F as “signal” for oxygen present in copper at ... Ce...
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BRIEFS

Highlights of Articles in This Issue

An Analytical Method for Polynuclear Aromatic Compounds in Coke Oven Effluents by Combined Use of Gas Chromatography and Ultraviolet Absorption Spectrometry

Ensemble Averaging in Gas Chromatography The ensemble averaging technique has been shown to be applicable in gas chromatography by making analysis of ultratrace samples of methane.

The polynuclear aromatic compounds are collected in gas chromatographic fractions and then quantitatively mea­ sured by ultraviolet absorption spectrophotometry. T. D. SEARL, F. J. CASSIDY, W. H. KING, and R. A. BROWN, Esso Research and Engineering Company, Ana­ lytical & Information Division, Linden, N. J. Anal. Chem., 42, 954 (1970) Determination of Composition of Polyamide Resins by Trimethylsilylation and Gas Chromatography The trimethylsilyl derivatives of diamines, dibasic acids, and ω-amino acids are determined. Triethylamine is added as a hydrochloric acid scavenger and the catalyst for silylation. SADAO MORI and MOTOHISA FURUSAWA, Laboratory of Chemistry, Faculty of Engineering, Yamanashi University, Kofu, Japan, and TSUGIO TAKEUCHI, Department of Syn­ thetic Chemistry, Faculty of Engineering, Nagoya Univer­ sity, Nagoya, Japan Anal. Chem., 42, 959 (1970) Sources of Error in Measurement of Retention Times A theoretical and experimental study shows how it is possi­ ble to account for the effects of the signal noise and of fluctuations of column temperature, inlet and outlet pres­ sures, which determine the error of measurement of reten­ tion times. MICHEL GOEDERT and GEORGES GU/OCHON, Depart­ ment de Chimie, Ecole Polytechnique, 17 rue Descartes, Paris 5ème, France Anal. Chem., 42, 962 (1970) The Palladium Generator-Separator—A Combined Electrolytic Source and Sink for Hydrogen in Closed Circuit Gas Chromatography An electrochemical cell generates hydrogen carrier gas for a gas chromatograph and subsequently removes the hydrogen prior to the chromatographic detector. Sample enrichment, flow, and pressure programming are facilitated. J. E. LOVELOCK, P. G. SIMM0NDS. and G. R. SHOEMAKE, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, Calif. Anal. Chem., 42, 969

L. J. LORENZ, R. A. GULP, and L. B. ROGERS, Department of Chemistry, Purdue University, Lafayette, Ind: 47907 Anal. Chem., 42, 979 (1970)

Separation of Rare Earth Ions by Precipitation during Electromigration Rare earth ions are precipitated by oxalate in an agar gel column, and the free ions move over the precipitation products under the influence of direct current. The separation which results can be ascribed to exchange reactions. JORIS DEMAN, Kliniek voor Radiothérapie en Kerngeneeskunde, Akademisch Ziekenhuis, Rijksuniversiteit Gent, Belgium Anal. Chem., 42, 9S3 (1970)

pH Effects on Fluorescence of Umbelliferone The three fluorescence bands are assigned to the excited state acid-base species and to photolysis product. The choice of p H and excitation wavelength extends the useful range of emission properties. DAVID W. FINK and WALTER R. K0EHLER, Lever Bros. Research and Development, 45 River Road, Edgewater, N. J. 07020 Anal. Chem., 42, 990 (1970)

Determination of Oxygen in Copper by Helium-3 Activation Analysis A radioactivation analysis using low-energy 3 He as incident particle and 18 F as "signal" for oxygen present in copper at concentrations in the ppb range or higher is presented. The method is nondestructive, extremely sensitive, and rapid. DIANA M. LEE, CYNTHIA V. STAUFFACHER, and SAMUEL S. MARK0WITZ, Department of Chemistry and Lawrence Radiation Laboratory, University of California, Berkeley, Calif. 94720 Anal. Chem., 42, 994 (1970)

(1970)

Improved Gas Chromatographic Separations of Enantiomeric Secondary Amine Derivatives The solid form of the ureide of L-valine isopropyl ester was shown to give much faster separations of the enantiomers of secondary amine derivatives than the liquid form. J. A. CORBIN and L. B. ROGERS, Department of Chemistry, Purdue University, Lafayette, Ind. 47907 Anal. Chem., 42, 974 (1970)

Calibration Method for lron-55 X-Ray Sulfur Gauges without Sulfur Standards Pure hydrocarbons only are required with œ F e . Exact mass absorption coefficients are not used; instead literature values of /us/Vc and JUH/JUC are used to simplify the calibration. B. A. FRIES, Chevron Calif. 94802

Research

Company,

Richmond,

Anal. Chem., 42, 999 (1970) ANALYTICAL CHEMISTRY, VOL. 42, NO. 9, AUGUST 1970

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AC BRIEFS Ion-Selective Electrode Study of Trace Silver Ion Adsorption on Selected Surfaces The feasibility of using a silver ion-selective electrode for monitoring trace silver ion adsorption is demonstrated. Adsorption levels at 30 days increased in the order: Vycor(28%) < Polyethylene;uTeflon < Desicoted Pyrex < Pyrex(48%). RICHARD A. DURST and BENJAMIN T. DUHART, institute for Materials Research, National Bureau of Standards, Washington, D. C. 20234 Anal. Chem., 42, 1002 (1970) Effect of Static Magnetic Field on Oscillopolarography, Polarographic Maxima in Oscillopolarography I t is revealed that, b y the application of static magnetic field, certain types of oscillopolarographic peak currents are reduced and this fact can be utilized for the elucidation of the second kind of maxima in oscillopolarography. SHIZUO FUJIWARA, YOSH/O UMEZAWA, TERUHIKO KUGO, and MASARU H/KASA, Department of Chemistry, Faculty of Science, The University of Tokyo, Hongo 113, Tokyo, Japan Anal. Chem., 42, 1005 (1970) Photoluminescence Decay Curves: An Analysis of the Effects of Flash Duration and Linear Instrumental Distortions The effects of finite flash duration, various degrees of linear instrumental distortion, and alternate techniques of data reduction on experimentally measured values for photoluminescent decay times are described and analyzed. J. N. DEMAS and G. A. CROSBY, Department of Chemistry, Washington State University, Pullman, Wash. 99163 Anal. Chem., 42, 1010 (1970) Alternate Current Polarography: On the Existence of Inductive and Negative Faradaic Admittances Arising from Coupled Homogeneous Chemical Reactions Theoretical evidence is presented for two cases in which kinetic influence of coupled homogeneous chemical reactions can give rise to inductive or negative faradaic admittances under ac polarographic conditions. DONALD E. SMITH and HAROLD R. SOBEL, Department of Chemistry, Northwestern University, Evanston, III. 60201 Anal. Chem., 42, 1018 (1970) Apparatus Using Semiconductor Electrodes for the Measurement of Acid Concentrations A novel method and apparatus combining an ammonium fluoride electrolyte with a low resistivity iV-silicon anode is described. A variety of organic acids as well as inorganic acids containing metal salts can be analyzed. J. P. MCKAVENEY, Garrett Research and Development Division, Occidental Petroleum Corporation, La Verne, Calif. 91750, and C. J. BYRNES, Crucible Materials Research Center, Colt Industries Inc., P. 0. Box 988, Pittsburgh, Pa. 15230 Anal. Chem., 42, 1023 (1970)

Atomic Fluorescence Spectrometry of Aluminum, Molybdenum, Titanium, Vanadium, and Zirconium in Inert Gas Separated Nitrous Oxide-Acetylene Flames Aluminum and vanadium gave detection limits of 0.1 and 0.07 jug/ml, respectively, in an argon separated N2O/C2H2 flame. Among 23 ions studied none interfered with the former and only Al, Co, and W with the latter element. R. M. DAGNALL, G. F. KIRKBRIGHT, T. S. WEST, and R. WOOD, Chemistry Department, Imperial College, London S.W.7., U.K. Anal. Chem., 42, 1029 (1970)

Interelement Interferences in Atomic Absorption Analyses with the Nitrous Oxide-Acetylene Flame The effect of flame and instrumental variations on cation interferences was studied and significant reductions were achieved with proper selection of parameters. A new, more pertinent method of expressing flame conditions is presented. J. Y. MARKS and G. G. WELCHER, Advanced Materials Research & Development Laboratory, Pratt & Whitney Aircraft, Middletown, Conn. Anal. Chem., 42, 1033 (1970)

Flame Emission Method for Determining Heats of Combustion of Selected Compounds The flame spectroscopy method described in this paper appears to be a fast and simple way of determining heats of combustion. J. J. KROETEN, H. W. MOODY, and M. L. PARSONS, Department of Chemistry, Arizona State University, Tempe, Ariz. 85281 Anal. Chem., 42, 1040 (1970)

Computerized Analysis and Correction of Differential Scanning Calorimetric Data for Effects Due to Thermal Lag and Heat Capacity Changes A computer technique is presented for calculating the contour of the base line during a thermal transition from a single experimental DSC trace. Thermal lag and heat capacity changes are taken into account. H. M. HEUVEL and K. C. J. B. LIND, AKZO Research and Engineering n.v., Arnhem, The Netherlands Anal. Chem., 42, 1044 (1970)

Computer-Based System for Neutron Activation Analysis The computer program, the instrumentation, and the analytical procedure described have each been designed to fit into the overall scheme of analysis. D. D. TUNNICLIFF, R. C. BOWERS, and G. E. A. WYLD, Shell Development Company, Emeryville, Calif. Anal. Chem., 42, 1048 (1970) ANALYTICAL CHEMISTRY, VOL. 42, NO. 9, AUGUST 1970

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AC BRIEFS Fixed-Time Digital Counting System for Reaction Rate Methods

Identification and Determination of Freezing-PointDepressant Anti-Icing Additives in Hydrocarbon Fuels by Infrared Spectrometry

A fixed-time instrument is described for reaction rate mea­ surements which uses digital computation circuitry. Per­ formance of the instrument on synthetic signals and phos­ phate samples indicates excellent precision, accuracy, and noise immunity.

Hexylene glycol, methoxy glycol, methanol, and isopropanol in gasolines, and methyl Cellosolve in jet fuel are iden­ tified and determined by their OH stretching bands in dilute solution.

J. D. INGLE, Jr., and S. R. CROUCH, Department of Chemistry, Michigan State University, East Lansing, Mich. 48823 Anal. Chem., 42, 1055 (1970)

R. K. RITCHIE and D. KULAWIC, Gulf Oil Canada Limited, Research and Development Department, Sheridan Park, Ontario Anal. Chem., 42, 1080 (1970)

Analysis of Thin Films by Ion Microprobe Mass Spectrometry

Notes

An ion microprobe mass spectrometer has been used to in­ vestigate isotopic and compositional gradients in thin films. With sputter rates of 0.5 A/sec, depth resolutions of the order of 20 A have been realized.

Quantitative Analysis of Ternary and Quaternary Semiconducting Alloys with Electron Microprobe

C. A. EVANS, Jr. and J. P. PEMSLER, Ledgemont Labora­ tory, Kennecott Copper Corp., Lexington, Mass. 02173 Anal. Chem., 42, 1060 (1970)

Application of Photoelectron Spectrometry to Pesticide Analysis. Photoelectron Spectra of Five-Membered Heterocycles and Related Molecules The analytical significance of the photoelectron spectra of 5-membered heterocycles and related compounds is dis­ cussed and it is shown that they could be used for qualita­ tive identification. A. D. BAKER, D. BETTERIDGE, N. R. KEMP, and R. E. KIRBY, Chemistry Department, University College of Swansea, Singleton Park, Swansea, U.K. Anal. Chem., 42, 1064 (1970)

This method employs theoretical calibration curves for mi­ croprobe analysis of a number of ternary semiconducting alloys formed by compounds from the II-VI, IV-VI, III-V, and III-VI groups. MARY C. FINN, Lincoln Laboratory, Massachusetts tute of Technology, Lexington, Mass. 02173

Insti­

Anal. Chem., 42, 1084 (1970) Spectrophotometric Determination of Trace Amounts of Mercury(ll) by Extraction with Bindschedler's Green The tri-bromo-mercury(II) complex anion is extracted with the Bindschedler's green into 1,2-dichloroethane. Beer's law is obeyed over the range of 8 χ 10"' — 4 χ lO^ilf of mercury(II) with molar absorptivity of 1.7 Χ 105 mole" 1 cm"1 liter at 740 ταμ. MASAHIRO TSUBOUCHI, University, Tottori, Japan

Faculty

of Education,

Tottori

Anal. Chem., 42, 1087 (1970) Amperometric Determination of Mercury in Organomercurials and Proteins

Determination of Actinides in Biological Samples with Bidentate Organophosphorus Extractant A sequential analytical procedure for nine actinides using a new extractant is presented. Recovery of these elements from biological samples exceeds 90% with a sensitivity of 0.02 d / m / s a m p l e .

Bis(2-hydroxyethyl) dithiocarbamate was used as a reagent for submicro quantitative amperometric titrations of mercury(II) at platinum electrode. A procedure is presented for the rapid and accurate determination of 10-150 /tg of mercury ( I I ) .

F. E. BUTLER and R. M. HALL, E. I. du Pont de Nemours & Company, Savannah River Laboratory, Aiken, S. C. 29801 Anal. Chem., 42, 1073 (1970)

SARAH EHRLICH-ROGOZINSKY and RUTH SPERLING, Departments of Biophysics and Chemical Physics, The Weizmann Institute of Science, Rehovot, (sraef Anal. Chem., 42, 1089 (1970)

Anodic Oxidation of Lithium, Cadmium, Silver, and Tetra-n-Butylammonium Nitrates

Ultraviolet Spectrophotometric Determination of Sulfur Dioxide

Evidence is presented to indicate that anodic oxidation of nitrate is an irreversible process leading to a species that reacts very rapidly with other system components.

In \M H 2 SOi the molar absorptivity of SO= at 276 nm is 500. This fact forms the basis of a rapid method to mea­ sure S 0 3 in liquid or gaseous samples when iodometrie pro­ cedures fail.

R. R. RAO, S. B. MILLIKEN, S. L. ROBINSON, and C. K. MANN, Department of Chemistry, Florida State Univer­ sity, Tallahassee, Fla. 32306 Anal. Chem., 42, 1076

(1970)

M. W. SCOGGINS, Research and Development Division, Phillips Petroleum Company, Bartlesville, Okla. 74004 Anal. Chem., 42, 1091 (1970) ANALYTICAL CHEMISTRY, VOL. 42, NO. 9, AUGUST 1970

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AC BRIEFS Simultaneous Detection of Tritium and Radiocarbon in Solid Scintillation Thin-Layer Radiochromatography

Application of Isotopically-Labeled Bromine for the Determination of Trace Unsaturation in Alkanes

By multichannel pulse-height analysis of scintillations si­ multaneous two-label detection has been proved to be possible. Anthracene was added as scintillator. Criteria for optimizing the detection method are given.

A radiometric procedure is outlined for the quantitative determination of trace ( > 6.4 χ 10~* mole/ml) olefinic impurities in pure hydrocarbon solvent. Using radiogas chromatography, qualitative identifications were possible for concentration > 5 χ 10"" mole/ml.

T. B. MELO and SVE/N PRYDZ, institute of Physics, Uni­ versity of Oslo, Blindera, Oslo 3, Norway Anal. Chem., 42, 1093 (1970)

Potentiometric Titration of Halides in Their Mixtures A method is presented for a convenient determination of halides in their mixtures by potentiometric titration with silver nitrate in nonaqueous medium using 8-hydroxyquinolinc (oxine) to eliminate interference of Γ and Br" ions. THEODORE S. PROKOPOV, Department of Upper Iowa College, Fayette, Iowa 52142

Chemistry,

Anal. Chem., 42, 1096 (1970)

O. C. GADEKEN, R. L. AYRES, and E. P. RACK, Depart­ ment of Chemistry, University of Nebraska, Lincoln, Neb. 68508 Anal. Chem., 42, 1105 (1970) Determination of Picomole Amounts of Enzymatically Formed Adenosine 3,5-Cyclic Monophosphate by High Pressure Anion Exchange Chromatography High pressure pellicular anion exchange chromatography coupled to a sensitive 254 ηιμ flow cell has been used to quantiate adenosine 3',5'-cyclic monophosphate formed from A T P by the enzyme adenyl cyclase. GARY BROOKER, Departments of Medicine and Biochem­ istry, University of Southern California, School of Medi­ cine, Los Angeles, Calif. 90033 Anal. Chem., 42, 1108 (1970)

Spectrophotometric Studies of Complexes of 2-Benzoylpyridine-2-Pyridylhydrazone The use of 2-benzoylpyridine-2-pyridylhydrazone (BPPH) for the trace determination of selected metal ions is de­ scribed. JOHN E. GOING and RONALD T. PFLAUM, Department of Chemistry, University of Iowa, Iowa City, Iowa Anal. Chem., 42, 1098 (1970)

New Semimicroprocedure for Determination of Ferrous Iron in Refractory Silicate Minerals Using a Sodium Metafluoborate Decomposition The sample is decomposed by fusion with (NaF)2B 2 0 3 in an argon atmosphere. The melt is dissolved in excess standard dichromate and the excess is determined by titration with standard ferrous solution. ROBERT MEYROWITZ, United States Geographical Survey, Washington, D. C. 20242 Anal. Chem., 42, 1110 (1970)

Determination of Cobalt Using Cobalt-60 and Paper Chromatography

Aids for Analytical Chemists

Cobalt in NBS steel standards is equilibrated with °°CO, chromatographed on paper, and determined by beta count­ ing. As little as 0.1 microgram may be determined with a precision of 2%.

Preparation and Properties of Thin Gold and Platinum Films on Glass or Quartz for Transparent Electrodes

ROBERT S. MORSE and GEORGE A. WELFORD, Health and Safety Laboratory, U. S. Atomic Energy Commission, New York, Ν. Y. 10014 Anal. Chem., 42, 1100 (1970)

WILLIAM VON BENKEN and THEODORE KUWANA, Depart­ ment of Chemistry, Case Western Reserve University, Cleveland, Ohio 44106 Anal. Chem., 42, 1114 (1970) An Automatic Sample Changer for Infrared Spectrometry

Determination of Nitrogen Dioxide and Nitric Oxide in the Parts per Million Range in Flowing Gaseous Mixtures by Means of the Nitrate-Specific-Ion Electrode

EDWARD J. BAKKER, J. STUART FROST, and GORDON D. OGILVIE, Research Department, ICI Fibres Limited, Hookstone Road, Harrogate, England Anal. Chem., 42,1117

(1970)

Determination of 0.1 to 6 ppm total nitrogen oxides by means of a nitrate-specific-ion electrode is reported. Least squares data analysis yields a correlation coefficient of 0.9885.

Improved Exponential Dilution Flask for Gas Chromatography

RAYMOND D/ MARTINI, The Port of New York Authority, 111 Eighth Ave. at 15th St., New York, Ν. Υ. 10011

L. J. LORENZ, R. A. GULP, and R. T. DIXON, Department of Chemistry, Purdue University, Lafayette, Ind. 47907

Anal. Chem., 42, 1102 (1970)

Anal. Chem., 42, 1119 (1970) ANALYTICAL CHEMISTRY, VOL. 42, NO. 9, AUGUST 1970

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