Computers in Quantitative TL-Chromatography

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Abstract
The paper presents a discussion of the use of computers, mainly of the micro-processor variety, in devices for the photometric quantitation of TL-chromatograms. First a brief survey is given of the principal features of contemporary photometers specifically designed for chromatographic applications. The most sophisticated and expensive of these are dual wavelength instruments and at the present state of development only these have as yet been computerized. It is, however, anticipated that in the near future the use of computers will spread also to the less sophisticated single wavelength devices with a moderate price tag. The advantages are ease of operation as well as superior performance characteristics. The former is achieved using a computer to control the internal operation of the photometer and some of the possibilities open in this regard are discussed. The improvement in performance is achieved in a different way. Photometric quantitation of TL chromotograms requires a number of mathematical operations upon the signal on its path between the light source and the output display. The computer permits the use of almost any kind of signal transforms, transforms which would be completely impractical to carry out by traditional techniques. The acquired and preprocessed signal, which in a conventional device would be directly fed to the output recorder, can be subjected to “after-processing” with a substantial further gain in performance. The results obtained by computerized analysis are available in alpha-numerical form. Both hard and soft copy devices can be used. If desired a graphical display in analog form can also be obtained. The output information provided by the computer can be stored in extremely compact form on magnetic tape or disc with very fast access and retrieval.