Identification of industrial contaminants by infrared analysis of gas-chromatographic fractions

Abstract

The integration of a packed-column gas chromatograph and a dispersive infrared spectrophotometer has been examined using a commercially available 1-cm³ infrared gas/vapour cell. Infrared spectra of the individual components in a solvent mixture were obtained by fitting the gas chromatograph with a high ratio effluent splitter and either collecting the separated components at the splitter by using small-scale adsorption tubes, or by passing them directly into the infrared cell along a heated gas line. In the former mode, the adsorption tube is placed into the heated infrared cell and a complete mid-infrared spectrum obtained from the desorbed component. In the latter mode, individual components can be trapped in the infrared cell by use of a by-pass valve, or the infrared spectrophotometer can act as a functional group detector by monitoring the infrared absorbance of each component “on-the-fly” at a specific wavenumber or over a wavenumber range.