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feature, " P h o t o n Counting for Spec trophotometry," page 63 A, is the first of a series of four feature ar ticles on modern a u t o m a t e d instru mental methods of analysis b y H o w a r d V. M a l m s t a d t and his co workers a t the University of Illi nois. Other articles in t h e series, planned for publication later this year, include a Report for Analyti cal Chemists entitled "Automated R e a c t i o n - R a t e Methods of Analy sis," an I n s t r u m e n t a t i o n feature, " I n s t r u m e n t s for R a t e D e t e r m i n a tions," a n d a feature on a u t o m a t e d atomic fluorescence instrumenta tion. Professor M a l m s t a d t h a s been an outstanding leader in the design and development of new analytical in strumentation for the past two de cades. H i s books, "Electronics for Scientists" and the more recent "Digital Electronics for Scientists" (both with C. G. E n k e of Michigan State University, a former M a l m stadt student, as coauthor) have rapidly become classics. I n this month's discussion of photon count ing, D r . M a l m s t a d t enumerates t h e advantages and difficulties of mea suring the output of t h e photomultiplicr tube in a spectrophotometer by using direct digital techniques instead of t h e more standard analog methods. T h e article presents t h e basic a n d practical characteristics of photon-counting theory and sys tems to illustrate t h a t it can be made widely applicable for m a n y types of spectrophotometry includ ing absorption, fluorescence, emis sion, a n d scattering methods. Sev eral applications of photon counting are described, including considera tions for high-precision spectropho tometry, and some current commer cial systems are evaluated. T h e articles on reaction-rate (ki netic) methods will appear together in a fall issue. T h e inherent a d vantages and possible limitations of reaction-rate methods as compared
to equilibrium methods will be r e viewed a n d the general concepts of encoding reaction-rate information presented. M a j o r discussion will be focused on the automated, com puter-controlled systems t h a t m a k e it possible t o perform hundreds of accurate, sensitive a n d selective quantitative determinations per hour v i a rate d a t a a n d to more rapidly develop new methods. T h e principles and characteristics of several electronic-rate measurement methods and circuits which provide excellent noise i m m u n i t y will also be presented. T h e final article in the series will describe an a u t o mated atomic fluorescence system developed by Professor M a l m s t a d t and his coworkers. Other articles on automated in strumental methods of analysis which will appear later this y e a r or early next y e a r include Instrumen tation features entitled " T h e R e naissance in Polarographic a n d Voltammctric Analysis" by J u d B . F l a t o of Princeton Applied R e search Corp. and "Analog-to-Digital Conversion of Analytical D a t a " by Stuart P . C r a m of the University of Florida. T h e first of these will discuss i m p o r t a n t new develop ments in the fields of differential pidsc polarography, alternating cur rent polarography, fast linear sweep voltammetry, direct anodic strip ping voltammetry, and differential pulsed anodic stripping voltam metry, whereas t h e second will cover the q u a n t i t a t i v e aspects of digitiz ing and consider instrumentation performance a n d specifications for this i m p o r t a n t step prior to d a t a acquisition or reduction. T h e intention of our I n s t r u m e n t a tion features is to provide articles of broad interest which describe emerging instrumentation fields or techniques of great potential to a n a lytical chemistry. T h e scope of the features is quite wide, as a perusal of those previously p u b lished and those planned for t h e future reveals. Suggestions for feature topics or authors are wel come a n d should be submitted to Analytical Chemistry, 1155 16th Street, N . W . , Washington, D C 20036. AlanJ.Senzel
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ANALYTICAL CHEMISTRY, VOL. 44, NO. 8, JULY 1972 ·
61 A
