OCLI Instruments

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Response Characteristics

EDITORS' COLUMN AT LEAST a rudimentary under­ standing of digital and analog in­ strumentation systems and compo­ nents is rapidly becoming a neces­ sity for the practicing analytical chemist. The unwary scientist, tempted by the many new data han­ dling and digitizing devices avail­ able today, may incorporate an un­ wise combination of units into his system and actually degrade the output accuracy! In this month's Instrumentation feature, page 69A, Professor C. G. Enke of Michigan State University introduces a number of "data do­ mains" concepts which analytical chemists will find most useful in de­ signing and modifying analog, digi­ tal, and analog/digital measure­ ment systems and devices. Profes­ sor Enke has for a long time been a leader in educating scientists in the intricacies of electronics. His pres­ ent article provides a means of uti­ lizing the latest electronic devices, such as digital frequency meters, signal averagers, digital pH meters, "digitized" gas chromatographs and double-beam spectrophotometers, and Fourier transform spectrom­ eters, efficiently and effectively, with no more knowledge necessary than an understanding of the basic measurement process. In the future we shall feature, as a sequel to Professor Enke's ar­ ticle, a discussion and review of the analytical aspects of the digitiz­ ing step in digital instrumentation, authored jointly by Professor Stuart P. Cram of the University of Flor­ ida and Professor Harry L. Pardue of Purdue University. The quanti­ tative aspects of digitizing and in­ strumentation performance and specifications will be considered for this important step prior to data ac­ quisition or reduction. The similar­ ities and differences between volt­ age-to-frequency conversion and analog-to-digital conversion also will be stressed. We hope that the two-part series of articles mentioned above will

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Now, Side-window arrangement in a reliable photomultiplier tube (S-20) by Hamamatsu Expand the wavelength range of your spectrophotom­ eter with the new HAMAMATSU R-446 Side-Window Photomultiplier Tube. S-20 response —185-850 nm. Standard direct replacement requires no adaptation. The R-446 eliminates the need for several differentrange tubes or time-consuming interchanges. When your UV spectrophotometer analyses require wider wavelength coverage, lower noise, and/or higher sen­ sitivity, plug in the HAMAMATSU Side-Window R-446 and get all the response you need. Dependable, reli­ able, and available on 48-hour shipment. Write or call Dept. PT-AC11

OCLI Instruments 132 WATER STREET, SOUTH NORWAI.K, CONN. 06854 (203) 853-2224 Circle No. 6 on Readers' Service Card

ANALYTICAL CHEMISTRY, VOL. 43, NO. 1, JANUARY 1971

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