December 1973, Vol. 45, No. 14 Editor: HERBERT A. LAITINEN
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analytical chemistry The Seven Ages of an Analytical Method Even with the great diversity of methods available to modern analytical chemistry, we can identify a common set of seven phases through which a method passes, analogous to Shakespeare’s seven ages of man. In tracing these phases, it is interesting to keep in mind a single example. For the present purpose, we use infrared spectroscopy. First, there is the initiation or conception phase, which often occurs outside of analytical chemistry or even outside of chemistry. A principle of physics, such as absorption of infrared radiation, is recognized as the basis for identification and measurement. Second, experimental measurements are made in the research laboratory to establish the validity of the principle as the basis for useful measurements. At this stage, infrared spectroscopy became a valuable structural tool for the chemist. Third, developments in instrumentation bring the method from a laboratory curiosity into the hands of the nonspecialist. Infrared measurements moved from special darkened rooms in the basement, first into the special spectroscopy laboratory and finally into the general research laboratory. Fourth, detailed studies of principle and mechanisms are pursued with the aid of improved instrumentation. This represents the stage a t which the method matures as an accepted procedure in competition and cooperation with other approaches. This stage represents the crest of analytical research as distinguished from instrumentation research. Fifth, applications are enlarged to an ever-widening scope of areas with appropriate modifications in procedures. Here advances made, for example, in biochemistry are brought to bear on problems in polymer chemistry, food chemistry, etc. Research of this type is commonly published both in analytical chemistry journals and in specialized subject matter journals. Sixth, applications of well-established procedures are made to new as well as old problems. Normally, such applications do not appear as research papers in analytical chemistry, but are included in descriptions of experimental procedures. Certain procedures may become highly standardized, and find their way into compilations of standard test methods. Seventh, a period of senescence occurs as other methods of greater speed, economy, convenience, sensitivity, selectivity, etc. surpass the method under consideration. These various stages, of course, blend imperceptibly, and also a resurgence of the later stages may occur as new developments in instrumentation or theory come along. I t might be an interesting exercise for the student to classify a number of analytical techniques according to their phases of development, and to look for resurgences in their histories.
For submission o f manuscripts, see page 1162 A ANALYTICAL CHEMISTRY, VOL. 45, NO. 14, DECEMBER 1973
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