Analytical chromatography, species-specific detector

Figure 1. Use of analytical chromatography as an on-line species-specific detector for a preparative chromatographic process.

With today s advanced analytical procedures, it is possible to describe the composition of these fuels in considerable detail. By combining several sequenced liquid chromatographic separations with gas chromatography-mass spectroscopy and by using specific gas chromatographic detectors for sulfur compounds, it has been possible to identify the majority of individual sulfur species in some fuels (12-19). A typical separation scheme is shown... 

The identification of the chemical forms of an element has become an important and challenging research area in environmental and biomedical studies. Two complementary techniques are necessary for trace element speciation. One provides an efficient and reliable separation procedure, and the other provides adequate detection and quantitation [4]. In its various analytical manifestations, chromatography is a powerful tool for the separation of a vast variety of chemical species. Some popular chromatographic detectors, such flame ionization (FID) and thermal conductivity (TCD) detectors are bulk-property detectors, responding to changes produced by eluates in a characteristic mobile-phase physical property [5]. These detectors are effectively universal, but they provide little specific information about the nature of the separated chemical species. Atomic spectroscopy offers the possibility of selectively detecting a wide rang of metals and nonmetals. The use of detectors responsive only to selected elements in a multicomponent mixture drastically reduces the constraints placed on the separation step, as only those components in the mixture which contain the element of interest will be detected... 

There is a large variety of analytical problems that require the separation of radioactive species by column liquid chromatography. This need arises, for instance, in activation analyses, the separation of fission products or the separation of radioactively labelled compounds. Examples of special importance come from the biosciences, where labelled molecules are used in research on metabolism. Whenever a sample contains radioactive species, it is possible to follow their elution from a separation column specifically by radiometric detection. This review outlines briefly the principles of radiometric detection and radiometric detectors, concentrating on problems that arise from the combination of separations by high-performance column liquid chromatography with radiometric detection. 

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