Varieties of Hyphenated Gas

Varieties of Hyphenated Gas Chromatography with Mass Spectrometry... 

VARIETIES OF HYPHENATED GAS CHROMATOGRAPHY WITH MASS SPECTROMETRY... 

Many FT-IR spectrometers have external ports for optical coupling to dedicated accessories. The IR radiation is conveniently directed to/from the external ports by computer-controlled flip mirrors. A large variety of accessories, like an IR microscope, interfaces for gas chromatography (GC/FT-IR), liquid chromatography (HPLC/FT-IR), thin layer chromatography FT-IR (TLC/FT-IR), etc., is commercially available. This type of method combination is usually called a hyphenated technique. FTIR spectrometers can even be supplemented by a FT-Raman accessory. The versatile combination of FT-IR spectrometers with other instruments has substantially contributed to their abundance in most analytical laboratories. 

From a GC equipped with a suitable sample inlet and detector, more sophisticated, dedicated analytical systems can be constructed to tackle a variety of tasks. In essence, an extraction/ concentration device can be interfaced (hyphenated) to the analytical system so that once the required method or sequence is set up, a solid sample is loaded into an extraction cell and from then on analysis can proceed unattended and the end product wUl be an analytical report ready to be used by the spill responder. Since the extracted analytes are transferred to the GC without any dilution, improved sensitivity is an immediate benefit. Significant savings in time and reduced contamination can result since extraction and analysis are undertaken in one system without any further intervention. Direct analysis can also mean lessening the use of disposable glassware. Some of the following are simple hyphenated techniques requiring no major modification of the GC, while others require modification to the gas lines of the inlet system and careful consideration of the flow/pressure of the two systems. 

Charles 1. Wilkins is currently a Distinguished Professor in the Department of Chemistry and Biochemistry at the University of Arkansas (Fayetteville). His interests inclnde mass spectrometry of polymer and copolymer materials, Fourier transform mass spectrometry, and the development of new methods to improve the utility of analytical mass spectrometry. Past research has dealt with applications of laboratory computers in chemistry, graph theoretic analysis of chemical problems, and research in chemometrics. Investigations of hyphenated analytical systems such as gas chromatography-infrared mass spectrometry and HPLC-NMR have also been of interest. He is the author of more than 235 scientific papers and 21 book chapters, in addition to editing eight books on a variety of chemistry topics. 

One of the most fascinating fields of instrumental development in mass spectrometry (MS) is hyphenation the on-line coupling of various techniques to MS. Apart from the obvious combinations of straightforward coupling of gas chromatography (GC) or liquid chromatography (LC) to MS, a wide variety of other combinations has been described. This contribution pays attention to the rationale of hyphenated techniques and briefly indicates a number of typical applications. 

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