Elemental analysis of gas chromatographically separated fractions

In determining the composition of complex mixtures that are subjected to chromatographic separation, the elemental composition of the fractions is of crucial importance. First, it provides valuable information for identification. Second, it permits the quantitative analysis of unseparated zones of compounds that exhibit qualitative and even quantitative differences with respect to elemental composition. 

In the 1960s, when selective elemental detectors were virtually unknown, elemental analysis could be performed only by using chemical methods. Today these methods do not seem as essential as they used to be. However, there are some very important reasons that prompt further work in this field the chemical methods and equipment are simple they allow the use of the simplest detectors, such as TCDs and plasma ion detectors they allow the calculation of individual calibration coefficients they are accurate and they make it possible to determine the ratio between elements in the course of a single experiment. 

In some instances other detectors may be preferred over TCDs. Windsor and Denton [174], e.g., applied inductively coupled plasma atomic emission spectrometry to the elemental analysis of GC effluents. 

Further development of the method has made it possible to apply it to the analysis of labelled compounds [130]. The conversion to hydrogen and carbon dioxide and separate determination of the activity of these chromatographic zones with the aid of flow-through counters have substantial advantages over the conventional method for measuring the activity of different compounds (1) an important factor is the operational stability of the flow-through counter (2) measurements can be made at room temperature, so that sophisticated equipment is not necessary (3) it is possible to determine simultaneously the activity with reference to C and H in doubly labelled molecules. 

Tliis is an example of how analytical reaction gas chromatography can be used for both elemental and isotopic analysis. The application of elemental analysis to radiochromatography was dealt with in great detail by Roberts [131]. 

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