V O L U M E 2 3, NO. 7, JULY
19 A
1951
THE ANALYSTS' COLUMN Physical Methods Group of the Society of Public Analysts. He said that it was tempting—but somewhat artificial—to attempt to distinguish between analytical procedures that employ entirely new physical principles and those that have been made possible or at least accessible essentially by virtue of developments in instrumentation. Certainly microwave spectroscopy and high-frequency titrimetry, electron and neutron diffraction, radioactivation analysis, and the various techniques covered by the terms ion exchange and chromatography, belonged essentially to this half-century ; but absorption and diffraction of x-rays, mass spectrometry, and infrared or fluorescence spectrography, which had been studied by research and academic chemists for many years, owed their present status and significance in the field of analytical chemistry essentially to profound developments in sources and receivers of energy, and in amplifying and recording devices. In a necessarily superficial survey of contemporary physical methods of analysis, he traced the influence of such factors as the increasing variety and complexity of analytical problems, the goal or the necessity (as in work with rare, unique or highly radioactive materials) of using ever smaller samples, and the demand for increased productivity—more analyses in less time with less trained staff. In some cases the commercial availability of a good instrument—e.g., the Spekker absorptiometer or the Beckman DU spectrophotometer—had had profound effects in extending the quality, scope, accuracy, and popularity of a wide variety of analytical procedures. In other cases—e.g., the quantometer, automatic recording infrared spectrometers, or mass spectrometers—a single instrument carried out concurrent analyses for a number of constituents in a complex mixture and replaced the traditionally trained analyst by computers and maintenance technicians. When the same type of analysis was being constantly repeated, it might be economically justifiable to build a special instrument based on a more flexible "research laboratory" prototype. A "push-button" polarograph for determining the lead in Ethyl gasoline formed an excellent example of this type of development. Concluding with a survey of potentiometric methods of analysis, Irvingmentioned such topics as cybernetics, economy of effort, and sundry instrumental and mathematical devices for locating the maximum of the potential being measured as a function of titrant volume.
Associate Editor
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