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eluted components, and consequently their empirical formulae to aid in substance identification. The
system is also used as a specific detector, to reduce the need for high-resolution columns when
analyzing highly complex mixtures. Finally, the GC/AS tandem system is also used for trace analysis
and, in particular, for following the speciation of selected elements in a mixture. The inductively
coupled and the microwave induced plasma emission spectrometers are those most often associated
with the gas chromatograph. Microwave induced plasma is not nearly as energetic as inductively
induced plasma, and so reagent gases are employed to help energy transfer between the plasma atoms
and molecules, and the sample atoms. For this reason, a number of reagent gases are usually made
available for the plasma torch. One problems with the microwave induced plasma is that it is easily
quenched by excessive loads of high carbon content material and, in particular, the solvent front from a
gas chromatograph. An alternative, energy coupling technique, called capacitively coupled microwave
plasma has largely overcome the problem of plasma extinguishing by solvent overload. Employing a
GC/AS tandem system chromatograms can be reproduced based on the presence of a specific element.
The high sensitivity coupled with the extreme element selectivity has made the GC/AS instrument
extremely valuable for environmental studies. In particular the tandem system has been used effectively
in the examination of tin contamination in water supplies, soils and sediments. The basic difference
between the ICP torch and the MIC torch in GC/MS is the method of energy transfer, the physical
arrangement of both torches being fundamentally similar. The ICP torch may not always provide good
spectra for the common elements, but is very sensitive to elements of higher atomic weight, and in
particular the metallic elements. In tandem systems it is commonly used in conjunction with capillary
columns. A GC/MS employing the ICP torch has been used to monitor chemical pathways of heavy
metals in coal during coal gasification processes.

References

1. D. Quimby and J. J. Sulllivan, Anal. Chem., 62(10)(1990)1027.

2. C. I. M Beenakker, Spectrochim. Acta, 32B(1977)173.

3. C. I. M Beenakker and P. W. J. M. Boumans, Spectrochim. Acta, 33B(1978)53.