HIGHLIGHTS
AC BRIEFS
TECHNICAL
OF THE
SCIENTIFIC
ARTICLES
IN T H I S
ISSUE
Nuclear Magnetic Resonance Investigation of Ligand Exchange Kinetics in the Calcium ( I I ) EDTA System
Theoretical Calculation of the Transport of Metal Vapors through the Discharge Column of a Direct Current Arc Results of the mathematical theory developed agree closely enough with experimental data to clarify the essential features of the transport mechanism. It is shown that Hie influence of transport mechanism on spectral-line intensities can be described in terms of essentially the same parameters as the excitation conditions.
The p H dependence of the exchange rate in aqueous solu tion has been evaluated, and the studies indicate that several reaction paths are available for exchange. RICHARD
J . KULA
and G E O R G E
H.
REED,
Department
of
Chemistry, The University of Wisconsin, Madison, W i s . A n a l . C h e m . 3 8 , 697 ( 1 9 6 6 )
P. W . J . M . B O U M A N S and L. de G A L E N , Laboratory for A n a lytical Chemistry, University of Amsterdam, Amsterdam,
A N D
Nether
lands A n a l . C h e m . 38, 674 ( 1 9 6 6 )
Energy Dispersion for Quantitative X-Ray Spectrochemical Analysis Unusual Adsorption Effects in the Electrochemical Reduction of Flavin Mononucleotide a t Mercury Electrodes The influence of adsorption of the oxidized form was studied with chronopotentiometry and cyclic voltammetry. It is demonstrated that the prewave resembles the Brdicka pnnvave only because during the lifetime of a mercury drop no appreciable, adsorption of the oxidized form can take place.
A multichannel analyzer and a computer program were applied in the analysis of allo3's of nearest and next near est neighbors in the transition metal group. Stainless steels and high temperature alloys were used to show that energy dispersion is best suited to the determination of major constituents (above 3%) with a precision of a few per cent. L. T. BIRKS, R. J . LABRIE and J . W . CRISS, U . S. N a v a l Research Laboratory, Washington, D. C .
A . M . H A R T L E Y and G . S. W I L S O N , Department of Chemistry and Chemical Engineering, University of Illinois, Irbana, I I I .
A n a l . C h e m . 38, 701 ( 1 9 6 6 )
61803
A n a l . C h e m . 38, 681 ( 1 9 6 6 )
Cryoscopic Titrations. Principles of a New Method of End-Point Detection An apparatus for continuously recording the variation in the freezing point depression during the course of a titra tion is described and applied to several model aqueous systems. Accuracy was approximately 1%, and the ex perimental titration curves agreed with the theoretical predictions. S T A N L E Y B R U C K E N S T E I N and N I C H O L A S
E. V A N D E R B O R G H ,
Effect of pH and Ionic Strength on the Distribution Coefficients of Alkaline Earth Metals and Nickel with Chelating Ion-Exchange Resins Results with Dowex Λ-1 indicate that nickel forms a 1:1 molar ratio chelate complex with the iminodiacetate groups at p H 4 and below and that the alkaline earths enter the resin in a 1:2 ratio at p H 4 and form the 1:1 ratio complex only at high p H after neutralization of the second hydrogen.
School of Chemistry, University of Minnesota, Minneapolis, M i n n . JERRY L. SIDES and C H A R L E S T. K E N N E R , Department of C h e m
55455 A n a l . C h e m . 3 8 , 687 ( 1 9 6 6 )
istry, Southern Methodist University, Dallas, Texas
75222
A n a l . C h e m . 38, 707 ( 1 9 6 6 )
Further Study of the Iodide-Iodine Couple a t Platinum Electrodes by Thin Layer Electrochemistry The esults show that 2 χ 10~° mole/cm. 2 of iodide ion or 2 X 10"° mole/cm. 2 of iodine is adsorbed in a nonelectroactive state, and that an additional 1 X 10" mole/cm. 2 of iodine, b u t no iodide, is adsorbed in an electroactive state. A R T H U R T. H U B B A R D ,
ROBERT A . O S T E R Y O U N G ,
Quantitative X-Ray Spectrographs Determination of Traces of Elements Using Direct Electron Excitation Limits of detection for Zn, Cu, Si, and Mg in aluminum, Co in low alloy steel, Ρ in bronze, and X a in a graphite matrix are reported.
and FRED
C . A N S O N , G a t e s and C r e l l i n Laboratories of Chemistry, C a l i f o r
C. J . TOUSSAINT
nia Institute of Technology, Pasadena, C a l i f .
C C R , Euratom, Ispra, Italy
A n a l . C h e m . 3 8 , 692 ( 1 9 6 6 )
and GILBERT
V O S , Chemistry
Department,
A n a l . C h e m . 3 8 , 71 I
VOL. 3 8 , N O . 6, MAY 1 9 6 6
(1966)
·
9 A
AC BRIEFS Computational Methods for Resolution of Mass Spectra Two computational methods, those of normal equations and of quadratic programming, are presented and their effectiveness compared. I t is concluded that for less than 40% overlap, the effect of noise is small, while for overlap greater than 70%, resolution should be difficult.
Solution Technique for Analysis of Silicates The solution, suitable for colorimetry, spectrography, or x-ray fluorescence or emission spectrometry, is effected by adding the melt of sample fused with lithium metaborate directly to cold, dilute nitric acid that contains the internal standard cobalt. Results of analyses by emission spec trometry are given for oxides of Si, Al, Mg, Ca, Sr, Ba, Ti, Mn, Fe, Cr, Cu, Zn, Zr, and Ni.
D A V I D G . LUENBERGER, Stanford Electronics Laboratories, Stan f o r d , C a l i f . , U L R I C E. D E N N I S , G e n e r a l
Electric C o . , San Jose,
Ν . Η . S U H R and C . O . I N G A M E L L S , M i n e r a l Constitution Lab oratories, The Pennsylvania State University, University Parle, Pa.
Calif.
A n a l . C h e m . 38, 730 ( 1 9 6 6 )
A n a l . C h e m . 38, 715 ( 1 9 6 6 )
Mass Spectra of Isocyanates Results of the examination of the mass spectra of isocyanic acid and 14 isocyanates are given. J O H N M . R U T H and R O G E R J . PHILIPPE, Research Department, L i g g e t t and Myers Tobacco C o . , Durham, N . C .
Flame Emission and Dual Flame Emission-Flame Ionization Detectors for Gas Chromatography Instrumentation variables of a hydrogen-air flame emis sion detector employing interference filters and standard gas chromatography instrumentation were studied. T h e influence of structure on response ratios was demon strated. Detection sensitivity was in the microgram range.
Anal. Chem. 38, 720 (1966) ROBERT S. B R A M A N , I IT Research Institute, C h i c a g o , I I I . A n a l . C h e m . 3 8 , 734 ( 1 9 6 6 )
Analysis of the Lower Free Fatty Acids from Microbial Fermentations Λ routine procedure is described for the quantitative isola tion of C1-C3 fatty acids by steam distillation and analysis by gas-liquid chromatography. T. C . G R E Y a n d B. J . STEVENS, Food Research Institute, Earlham Laboratory, Norwich, and Low Temperature Research Station, C a m
An Assay Method for Vinyl Grignard Reagents Using Gas Chromatography The content of tributylvinyltin after treatment of the vinyl Grignard reagent with an excess of tributyltin chlo ride indicates the concentration of the reactive vinyl group in the Grignard.
bridge, England A N A T O L E W O W K and S A L V A T O R E D i G I O V A N N I . M & T C h e m A n a l . C h e m . 38, 724 ( 1 9 6 6 )
icals Inc., Rahway, N . J . A n a l . C h e m . 38, 742 ( 1 9 6 6 )
The Preparation and Characterization of Lyophilized Polyacrylamide Enzyme Gels f o r Chemical Analysis The preparation of enzyme gels which can be accurately weighed and used in packed columns of a standard size to give reproducible activity measurements is described and the particles are characterized.
Determination of Petroleum W a x Odor by Gas Chromatography The results of a gas chromatographic determination of petroleum wax odor can be easily correlated with the olfactory rating of wax samples as defined b y an odor panel.
G . P. H I C K S and S. J . U P D I K E , D e p a r t m e n t of M e d i c i n e , Univer
L A R R Y R. DURRETT, Shell O i l C o . , Houston Research Laboratory,
sity of Wisconsin, Madison, W i s .
P. O . Box 100, Deer Parle, Texas
77536
A n a l . C h e m . 3 8 , 726 ( 1 9 6 6 ) Anal. Chem. 38, 745 (1966) M -
