tive and advisory body to the various product groups when test procedures involve methods using absorption spectroscopy. There are subcommittees on apparatus specifications. They work with manufacturers and other committees to see that the instrument will perform the test under study in a satisfactory and reproducible manner. This is important, of course, for the work of individual laboratories but more important is that several laboratories using different instruments come out with answers within acceptable limits. A subcommittee on methods is commissioned with establishing ASTM procedures involving infrared spectrophotometry. I t expects to evolve a standard format for such procedures, so that instrument operational details will not have to be repeated for each procedure. This, of course, involves a careful study of what is fundamental and repetitive in infrared procedures. Similar groups are working in the field of ultraviolet and visible. They are also taking a hard look a t what is common to all these methods, which are after all only working in different parts of the spectrum. While they have this in common, the instrumentation is usually different. However, there is rather expensive equipment now on the market covering a greater part of the spectrum of use to analysts. These committees are not overlooking the fact that sample preparation is very important, as well as separation techniques, such as chromatography, which can be used to bring the sample into a form that can be analyzed by physical approaches. The subcommittee on nomenclature is hammering into shape definitions, terms, and symbols in the field of spectroscopy, many of which have already been tentatively accepted. Finally, a subcommittee on standard data is working and collaborating with others in collecting spectroscopic data and coding them on IBM or other systems. ASTM is acting as a clearinghouse for collecting and selling such card decks. This is a rather staggering assignment and more cooperation and organization are required to make the project of maximum usefulness. Again it is a program of voluntary service. To date 10,969 infrared, 7666 ultraviolet, and 13,899 formula name cards hare been collected; 200 infrared and 80 ultraviolet decks have been sold by ASTlM. No cards in the visible have been issued, but 900 have been coded. When a committee completes an assignment, the report is published by ASThI. Analysts, especially those using physical methods, will find the findings of Committees E-2 and E-13 of practical value in their daily work. Present progress indicates some tentative reports will be ready within a year. V O L U M E 28, NO. 4, A P R I L 1 9 5 6
THE MODEL 2 1 The Standard Instrument for Infrared Analysis T h e complete story of the dependability of the Model 21 double beam recording infrared spectrophotometer is being told by its users-in the laboratories of industry, the universities and private research organizations throughout the United States and abroad. T h e hlodel 21 is the prime tool of the infrared field. Designed to provide both high quality survey spectra and precise quantitative data routinely, the Model 21’s full capabilities are there when needed, A continuing program of instrument improvement and development insures the Model 21’s position. Accurate and precise, it off ers complete flexibility in resolution, spectral presentation and recording speeds ( with single switch automatic control, once operating conditions are chosen). A complete range of accessories extends its versatility: 5 different prism materials providing maximum resolution and range . . , 7 quick interchange assemblies recording linearly in waivelengths and wavenumber. . , gas cells from 5 cm to 1 0 14 in path length. . liquid cells, both macro and micro, high and low pressure, and with variable path length. . . polarizers, heatable cells, reflectance attachments for solid state studies, and so on. T h e wavelength -range of the Model 21 with standard optics is from 800 millimicdns to 15.5 microns covering the near infrared and fundainental regions of the spectrum. These two useful regions complement each other, and any Model 21 covers both. T h e RIodel 21 is a product of Perkin-Elmer, world leader in infrared instrumentation, with its own sales a n d service offices throughout the United States.
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