ANALYTICAL CHEMISTRY
NEWS
Special Analytical Techniques Highlight LSU Symposium Recent extensions to analytical theory as applied to prob lems described b y noted speakers
Baton R o u g e , L a . Unusual applications of analytical methods added special interest to this year's Louisiana State University Symposium on M o d e m Methods of Analytical Chemistry neld J a n u a r y 25-28 T e n speakers, each of whom gave two one-hour lectures, covered such diverse topics as use of induced reactions in analytical chemistry, analysis of semiconductor materials, a n d phosphorimetry. T h e more t h a n 300 who registered for t h e symposium also saw exhibits of t h e latest models of laboratory a n d analytical equiprnen.. b y 22 suppliers. As i r previous years several outstaridmt, speakers iroir E u r o p e d e scribed their recent work. F r o m E i g and's Atomic E n e r g y Research E s t a b lishment a t Harwell, I>r. G. W . C Alilrier discussed polar ography with special emphasis on pulse technique. Jv. R o b e r t Mitchell of t h e Macaulay Institute for Soi: Research, Aberdeen, Scotland, covered spectrochemical methods for trace analysis of soils. I n d u c e d R e a c t i o n s . E v e n though induced reactions provide a serious nuisance to t h e interpretation of reaction mechanisms, D r . I . M . Kolthoff of the University of Minnesota told how these reactions are useful in very sensitive detection a n d determination of trace amounts of metals. Induced reactions occur in reactions of F e + 4 , C - + 6 , Mn + T As + 3 , a n a T e ^ ' . lor example. Understanding t h e reaction mechanism aids in using induced reactions or in éliminaΜ,',Ε their a p p a r e n t effects Free radicals n a y be caused b y m auceci reaction.-: In s'-me cases, D r . Kolthoff sail! an intei ;ediate vaience state exista uuriug or:· ation-reductio:·^ reactions, u c ; e •· i t η-.robe.·· of elec trons clonal. ; a reducing agent is different from tm- m i m ' . ; r acceptée b> an oxidizing agent. MoWm ^ " m^rf *. sen v ' )f 10 Iifetn ^OÎ renie ι ' a lin m « λ
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QUICK! Which sink takes the sulphuric?
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tensity and steadiness of the signals in flame photometry and atomic absorption spectroscopy. In both techniques, air-fuel ratio, flame position, and sample feed rate have important effects. Generally, said Robinson, flame photometry is most useful for determining group 1 and 2 elements and many transition elements. It is of little use for noble metals, the zinc sub-group, and non-metals. Atomic absorption spectroscopy works well for noble metals, the zinc sub-group, and transition elements, but not for the analysis of non-metals and metals such as aluminum and vanadium that form refractive oxides. Best operating conditions for the two methods vary widely. A low feed rate (0.06 ml. per min.) and use of the spectrum from the tip of the inner cone is best for flame photometry. On the other hand, atomic absorption spectroscopy works best with a feed rate limited to the rate of combustion of the solvent in the flame and with a signal from the flame's outer cone. Ion Exchange Separations. Several variations of ion exchange technique were described by Dr. James S. Fritz of Iowa State University. Complexing with EDTA (ethylenediamine tetraacetic acid) and close control of pH gives excellent quantitative separation of metal ions with short—five cm. —columns. On the basis of studies of individual ions, Dr. Fritz said that separation of mixtures may be predicted. Another use of ion exchange columns is separation of metal groups by
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CHEMICAL CERAMICS
DIVISION
U. S. S T O N E W A R E AKRON 9, OHIO
105-G
Circle No. 14G on Readers' Service Card
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ANALYTICAL CHEMISTRY
U. S. and foreign speakers were on the LSU program. One of the foreign visitors. Dr. Robert Mitchell, Macaulay Institute for Soil Research, Aberdeen, Scotland (left) is shown with Dr. James W . Robinson, Esso Laboratories, Baton Rouge, La.
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