A C BRIEFS

the burner air supply. The detection limit for the method, calibrated by a filtration technique, is ca. ... BRIAN P. CAUGHLEY, Wellington Polytechnic,...
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A C BRIEFS Highlights of Articles in This Issue

Real-Time Computer Optimization of Stationary Electrode Polarographic Measurements

Novel Impedance Measurements on Ion-Selective Liquid-Membrane Electrodes

Results indicate an improvement in quantitative resolution of overlapping reduction signals, provided a minimum E1/2 separation of about ISO mV is present.

Evaluation of several commercially available membrane electrodes was carried out in detail as a function of frequen­ cy and solution variables.

S. P. PERONE, D. 0. JONES, and W. F. GUTKNECHT, Department of Chemistry, Purdue University, Lafayette, Ind. 47907

M. J. D. BRAND and G. A. RECHNITZ, Chemistry Depart­ ment, State University of New York, Buffalo, Ν. Υ. 14214 Anal. Chem., 41, 1185 (1969)

Anal. Chem., 41, 1154 (1969)

Fitting of Analytical Functions with Digital Computers in Spectrochemical Analysis One of two procedures presented is for computers allowing conversational-mode operation; the other is for batch-load­ ing systems. Both have provisions for selecting the proper functions and for rejection of aberrant data. MARVIN MARGOSHES and STANLEY D. RASBERRY, Spec­ trochemical Analysis Section, National Bureau of Stand­ ards, Washington, D. C. 20234

Optimizing Concentration Determinations in the Presence of Adsorption Phenomena Using the Vibrating Dropping Mercury Electrode The V D M E is shown to be significantly superior to the D M E for most analytical purposes where adsorption phe­ nomena can inhibit electrode response. JAMES G. CONNERY and RICHARD E. COVER, Depart­ ment of Chemistry, St. John's University, Jamaica, New York 11432 Anal. Chem., 41, 1191 (1969)

Anal. Chem., 41, 1163 (1969) Electrochemistry of Manganese(lll)-(ll) Hematoporphyrin IX Couple Direct Determination of Silver in Air by Atomic Absorption Spectrometry Air containing finely divided silver iodide is introduced in the burner air supply. The detection limit for the method, calibrated by a filtration technique, is ca. 3 Mg/m3. HARRY W. EDWARDS, Department of Mechanical Engineer­ ing, Colorado State University, Ft. Co///nsr Colo. 80521

Adsorption of these compounds is extensive at mercury elec­ trodes. Several coupled chemical reactions are found to be associated with the electron transfer reaction. DONALD G. DAVIS and JOSEPH G. MONTALVO, Jr., De­ partment of Chemistry, Louisiana State University in New Orleans, New Orleans, La. 70122 Anal. Chem., 41,1195

(1969)

Anal. Chem., 41, 1172 (1969) Selectivity Studies on Liquid Membrane, Ion-Selective Electrodes Volatility of High Boiling Organic Materials by a Flame Ionization Detection Method An apparatus and method are described for the rapid and sensitive determination of the volatilization pattern and vapor pressure of high boiling organic materials. F. T. EGGERTSEN, E. E. SEIBERT, and F. H. STROSS, Shell Development Co., Emeryville, Calif.

Selectivity ratios are shown to depend on concentration lev­ els. A procedure for the consistent numerical determination of selectivity ratios is presented. K. SRINIVASAN and G. A. RECHNITZ, Department of Chemistry, State University of New York, Buffalo, Ν. Υ. 14214 Anal. Chem., 41, 1203 (1969)

Anal. Chem., 41, 1175 (1969)

Total Luminescence of Coumarin Derivatives Isolated from Expressed Lime Oil The crystalline components responsible for the room tem­ perature fluorescence, low temperature phosphorescence, and low temperature fluorescence of expressed lime oil have been isolated and identified.

Difference between the Inflection Point and the Equivalence Point in Coulometric Titrations of Weak Acids Coulometric titrations of boric acid in media containing dif­ ferent concentrations of mannitol are used to verify the the­ oretical relationship between potentiometric inflection point and equivalence point.

HOWARD W. LATZ and BROOKS C. MADSEN, Department of Chemistry, Ohio University, Athens, Ohio 45701

GEORGE MARINENKO and CHARLES E. CHAMPION, In­ stitute for Materials Research, National Bureau of Stand­ ards, Washington, D. C. 20234

Anal. Chem., 41, 1180 (1969)

Anal. Chem., 41, 1208 (1969)

VOL. 41, NO. 10, AUGUST 1969 · 9 A

A C BRIEFS High-Frequency Titrimetric Determination of Total Base Number of Lubricating Oils This high-frequency method eliminates the possibility of contamination of the electrodes, always obtains a sharp break in the graph at the end-point, and yields more reproducible and meaningful results. BRIAN P. CAUGHLEY, Wellington Polytechnic, Private Bag, Wellington, New Zealand, and MICHAEL V. JOBLIN, British Petroleum (New Zealand) Ltd., Waiwhetu, Wellington, New Zealand Anal. Chem., 41, 1211 (1969)

Dielectrometric Titrations: Acid-Base Titrations

Quantitative

Titrations between picric acid and triethylamine or N,N-dimethylbenzylamine in benzene were performed as examples of the technique described. ROBERT MEGARGLE, GEORGE L. JONES, Jr., and DONALD ROSENTHAL, Department of Chemistry, Clarkson College of Technology, Potsdam, New York 13676

Precise Gas-Chromatographic

Measurements

Digital control of sample injection, digital data acquisition, a ±0.02 °C column temperature control, and 0.01% carriergas flow rate control are combined in a high-precision chromatograph. J. E. OBERHOLTZER and L. B. ROGERS, Department Chemistry, Purdue University, Lafayette, Ind: 47907

of

Anal. Chem., 41, 1234 (1969)

Silylation of Asphalts within Gas-Liquid Chromatographic Columns. Effects on Inverse GLC Data and Infrared Spectra Phenol and propionic acid interact strongly with phenolic and carboxylic acid OH groups either initially present in asphalts or formed on oxidation. S. M. DORRENCE and J. C. PETERSEN, Laramie Petroleum Research Center, Bureau of Mines, U.S. Department of the Interior, Laramie, Wyo. 82070 Anal. Chem., 41, 1240 (1969)

Anal. Chem., 41, 1214 (1969)

Thermal Field-Flow Fractionation of Polystyrene Samples Multicomponent separations are effected using "reverse" temperature programming and fixed temperature increments. T h e methods separates molecular weights ranging from 3600 to 860,000. GARY H. THOMPSON, MARCUS N. MYERS, and J. CALVIN GIDDINGS, Department of Chemistry, University of Utah, Salt Lake City, Utah

Characterization and Gas Chromatography of Alkoxides of Aluminum and of Some Group IV Elements Al-tris-isopropoxide, tetrakis-isopropoxides of Ti, Zr, Hf, Si, and Ge, and tetrakis-tertiary amyloxides of Ti, Zr, and Hf are synthesized and characterized. L. M. BROWN, University of Cincinnati, Cincinnati, Ohio 45221, and K. S. MAZDIYASNI, Air Force Materials Laboratory, Wright-Patterson Air Force Base, Ohio 45433 Anal. Chem., 41, 1243 (1969)

Anal. Chem., 41, 1219 (1969)

Determination of Asphalt Molecular Weight Distributions by Gel Permeation Chromatography Various associated problems are examined: sample-size effects, detector response factors, sample adsorption, and molecular wt-elution vol correlations. An accurate procedure is described. L. R. SNYDER, Union Oil Co. of California, Research Center, Brea, Calif. 92621

Gas Chromatography of Catecholamine Metabolites Using Electron Capture Detection and Mass Spectrometry Pentafluoropropionates were the best derivatives in terms of stability, separation characteristics, high EC-response, and well-defined mass spectra. ERIK ANGGARD and GORAN SEDVALL, Department of Pharmacology, Karolinska Institutet, Stockholm, Sweden Anal. Chem., 41, 1250 (1969)

Anal. Chem., 41, 1223 (1969)

Rapid Analysis of Ribonucleosides and Bases at the Picomole Level Using Pellicular Cation Exchange Resin in Narrow Bore Columns The fovir major bases or nucleosides of R N A are analyzed at the subnanomolc level in less than 6 min using 3-m columns and high-flow velocities.

Quantitative Determination of 9-Methylcarbazoles in Cigarette Smoke The mainstream smoke of an 85-mm U.S. nonfilter cigarette contained 103 ng of 9-methylcarbazole, 11.8 ng of 1,9-dimethylcarbazole, 19.9 ng of 2,9- and 3,9-dimethylcarbazole, and 5.7 ng of 4,9-dimethylcarbazole.

CSABA HORVATH and S. R. LIPSKY, Section of Physical Sciences, Yale University School of Medicine, New Haven, Conn. 06510

DIETRICH HOFFMANN, GUNTER RATHKAMP, and STEPHEN NESNOW, Division of Environmental Cancerigenesis, Sloan-Kettering Institute for Cancer Research, New York, N.Y. 10021

Anal. Chem., 41, 1227 (1969)

Anal. Chem., 41, 1256 (1969) VOL. 41, NO. 10, AUGUST 1969 ·

11 A

A C BRIEFS Measurement of /^-Emitting Nuclides Using Cerenkov Radiation

Mechanisms in Coprecipitation of Berkelium(IV) with Cerium(IV) lodate from Homogeneous Solution

The specific variables studied were : sample volume, pulseheight distribution, detention efficiency, index of refraction, directional response, and gamma photon effects.

Removal of Bk from NaBrOs-HNOa solutions at room temperature usually follows a logarithmic law involving the difference in oxidation potentials of Bk and Ce.

H. H. ROSS, Analytical Chemistry Div., Oak Ridge National Laboratory, Oak Ridge, Tenn.

JOHN J. FARDY and BOYD WEAVER, Oak Ridge National Laboratory, P.O. Box X, Oak Ridge, Tenn. 37830

Anal. Chem., 41, 1260 (1969)

Anal. Chem., 41, 1299 (1969)

Neutron Activation Analysis of Uranium in Geological Material by Measuring Tellurium-132 The method which incorporates neutron activation of U, radiochemical separation of a fission product, Te1S2, and gamma spectrometry can determine U at the submicrogram level. A. D. SUTTLE, Jr., BARBARA C. O'BRIEN, and D. Wf MUELLER, Department of Chemistry, Texas A&M University, College Station, Tex. 77843

Determination of Oxygen in Lithium by the Vacuum Distillation Method The method is shown to be reliable for determining oxygen in lithium to the 30 ppm level. Reproducibility for the sample weight determined by this technique is ± 2 % . RANDALL F. GAHN, Lewis Research Center, National Aeronautics and Space Administration, Cleveland, Ohio Anal. Chem., 41, 1303 (1969)

Anal. Chem., 41, 1265 (1969)

Dielectric Method for Analysis of Water in Particulate Solids

Techniques for Measuring Surface and Bulk Optical Properties of Polyethylene Films

Accurate analysis is based on extracting water into p-dioxane and comparing the change in dielectric constant to the change produced by adding a known amount of water to dioxane.

Techniques are presented which allow the total light attenuated by the film to be divided into the attenuation caused by the individual phases.

SEYMOUR KATZ, WILLARD W. BACH, and WILLIAM A. REICHE, General Motors Research Laboratories, Warren, Mich.

BERT H. CLAMPITT, DALE E. GERMAN, and H. D. ANSPON, Gulf Research and Development Co., Kansas City Division, Merriam, Kans. 66202 Anal. Chem., 41, 1306 (1969)

Anal. Chem., 41, 1270 (1969)

Study of Thermal Effects Observed by Differential Thermal Analysis. Theory and Its Application to Influence of Sample Parameters on a Typical DTA Curve A mathematical model is developed to study the effects of sample and block parameters on the transfer of heat in a D T A apparatus. R. MELL7NG, F. W. WILBURN, and R. M. MclNTOSH, R&D Laboratories, Pilkington Brothers Limited, Lathom, Ormskirk, Lancashire, England

Extraction Equilibria for the System Toluene-3,4-Dithiol and Zinc Zinc is well extracted as either an ion association complex or as a mixed ligand complex. Several other divalent ions are also shown to extract with toluenedithiol. HOBART G. HAMILTON and HENRY PREISER, Department of Chemistry, University of Arizona, Tucson, Ariz. 85721 Anal. Chem., 41, 1310 (1969)

Anal. Chem., 41, 1275 (1969)

Theory of Curved Molar Ratio Plots and a New Linear Plotting Method By introducing an idea of "normalized absorbance" into the familiar molar ratio method, theoretical general equations are shown to describe curved plots encountered with weak complex systems. KOZO MOMOKI, JUN SEKINO, HISAKUNI SATO, and NOBORU YAMAGUCHI, Laboratory for Industrial Analytical Chemistry, Faculty of Engineering, Yokohama National University, Ooka-machi, Minami-ku, Yokohama-shi, Japan Anal. Chem., 41, 1286 (1969)

NOTES Polarography of Uranium(VI) Complexes with N-Hydroxyethyl-Ethylenediamine-Triacetic Acid Three kinds of chelate species, U0 2 (H 2 A) 2 , U 0 2 ( H A ) ^ and U02A*2 were confirmed polarographically and the distribution as a function of p H was determined. TSAI-TEH LAI and SHI-TSEUN LEE, Chemical Engineering Department, Cheng Kung University, Tainan, Taiwan, China Anal. Chem., 41, 1316 (1969) VOL. 41, NO. 10, AUGUST 1969 ·

13 A

A C BRIEFS Determination of Potassium-40 by Gamma Ray Spectrometry for Potassium-40/Argon-40 Geochronology K40 can be routinely determined by this method with a pre­ cision and accuracy satisfactory for most minerals used in K - A r work if at least 1-2 grams of sample are available. LUCIA CIVETTA and PAOLO GASPARINI, Istituto di Fisica Terrestre, Universita di Napoli, Largo S. Marcellino 10, Napo/i, Italy, and JOHN A. S. ADAMS, Department of Geology, Rice University, Houston, Tex. 77001

Weight of Unit Sheets in Petroleum Residues by Proton Nuclear Magnetic Resonance Proton N M R studies of G P C fractions of a petroleum resi­ due yield "unit sheet" weights consistent with currently held theories of residual structure. F. E. DICKSON, B. E. DAVIS, and R. A. WIRKKALA, Gulf Research & Development Co., Pittsburgh, Pa. Anal. Chem., 41, 1335 (1969)

Anal. Chem., 41, 1319 (1969) Polarographic Determination of Hydroxylamines and Some Hydrazine Derivatives The method employs the anodic waves produced by these compounds at the D M E in an aqueous solution of alkaline sodium sulfite. PALLE E. IVERSEN and HENNING LUND, Department of Organic Chemistry, University of Aarhus, 8000 Aarhus C, Denmark Anal. Chem., 41, 1322 (1969) Detection of Thioureido Groups in Open Chain and Heterocyclic Compounds by Hydrazinolysis Results indicate that all thioureido derivatives whether open chain or cyclic are potential precursors of the triazole. R. G. DICKINSON and N. W. JACOBSEN, Department of Chemistry, University of Queensland, Brisbane, Australia Anal. Chem., 41, 1324 (1969) Direct Determination of Fluoride in Phosphate Rock Samples Using the Specific Ion Electrode A citrate buffer is used to prevent interference from Al. Results for standard phosphate rock samples are in good agreement with those obtained by other methods. C. R. EDMOND, The Australian Mineral Laboratories, Adelaide, South Australia

Development

Anal. Chem., 41, 1327 (1969) Potentiometric Acid-Base Titrations in Tetramethylurea A glass-modified calomel electrode system was used to moni­ tor the progress of the titrations. Recoveries were satisfac­ tory for both acids and bases. SIEGMOND L. CULP and JOSEPH A. CARUSO, Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221 Anal. Chem., 41, 1329 (1969) Gas-Liquid Chromatographic Determination of Neomycins Β and C The method is based on silylation and chromatography of the derivatives on an OV-1 column. All active hydrogens on both the hydroxy and amine groups of neomycin are silylated.

Fractionation of Polyvinyl Alcohol on Deactivated Porous Silica Beads by Gel Permeation Chromatography Deactivation is demonstrated by reduced retention of pyri­ dine. Dextran calibration standards are shown to exhibit skewed distribution. KARL J. BOMBAUGH, WILLIAM A. DARK, and JAMES N. LITTLE, Waters Associates, Inc., 61 Fountain St., Framingham, Mass. 01701 Anal. Chem., 41, 1337 (1969)

Pressure Programming in Gas Chromatography with Open Tubular Columns Equations are obtained which related retention time to pro­ gramming rate. Experimental data are included and com­ pared with the theory. J. DANIEL KELLEY and JOHN Q. WALKER, McDonnell Laboratories, McDonnell Douglas Corp., St. Louis, Mo. 63166 Anal. Chem., 41, 1340 (1969)

Separation of Asphaltic Materials by Reversed Phase Partition and Adsorption Chromatography. Comparison of the Fractions by Infrared Spectrometry The effect of using liquid-liquid chromatography preceding liquid-solid chromatography to enhance the separation of asphaltics is studied. R. V. HELM, Laramie Petroleum Research Center, Bureau of Mines, Laramie, Wy. 82070 Anal. Chem., 41, 1342 (1969)

Spectrophotometric Determination of the Critical Micelle Concentration of Some Alkyldimethylbenzylammonium Chlorides Using Fluorescein CMC's are determined by the spectral-dye method using fluorescein and are in agreement with those obtained from surface tension measurements.

KIYOSHI TSUJI and JOHN H. ROBERTSON, Control Ana­ lytical Research and Development, The Upjohn Company, Kalamazoo, Mich. 49001

JOHN W. LEDBETTER, Jr., and JAMES R. BOWEN, Depart­ ment of Chemistry, Medical College of South Carolina, Charleston, S. C. 29401

Anal. Chem., 41, 1332 (1969)

Anal. Chem., 41, 1345 (1969)

VOL. 41, NO. 10, AUGUST 1969 · 15 A