Matrix independent headspace gas chromatographic analysis. This full evaporation technique

Abstract

This paper presents the full evaporation technique (FET) as a simple methodology to overcome the matrix effects which can be experienced in headspace and direct liquid injection chromatographic analysis. The technique involves dispensing a small aliquot of sample into a headspace bottle and thermal equilibration of the sample. It was found for most cases that reproducible results independent of time and temperature are generated by heating several milligrams of the sample at temperatures above 100°C for 5–10 min. The full evaporation methodology addresses the problems associated with the analysis of analytes in unpredictably changing sample matrices including soils, biological liquids, and a multitude of chemical and petroleum streams. This is especially advantageous for samples containing salts, mineral acids, polymers, detergents and other practically non-volatile constituents. The FET analysis of standard solutions prepared in various matrices provides a very uniform detector response indicating a reduction in sensitivity towards matrix effects. The described methodology offers sensitivity comparable to that of direct liquid injection while providing the benefits associated with traditional headspace analysis.