Discrimination and thermal degradation of toxaphene compounds in capillarygas chromatography when using split/splitless and on-column injection

Technical toxaphene and a 22-component Reference Mixture were analyzed usin g capillary gas chromatography with split/splitless injection (SSL) and on- column injection (OC). In both techniques, electron-capture, negative ioniz ation mass spectrometry (ECNI-MS) was used for detection of chlorobornanes, chlorocamphenes and related compounds. Significant discrimination of highl y chlorinated congeners was observed as a result of incomplete transfer of these compounds from the vaporizer to the analytical column when using SSL. This resulted in a much lower response for nona- and decachloro congeners than when using OC. In addition, several toxaphene components, especially t he chlorobornanes with gem dichloro substitution on the six-member carbon r ing, undergo thermal degradation when using SSL. Some of these congeners ar e major components of technical toxaphene, but generally are not present, e xcept at low concentrations, in environmental and biological samples. There fore, technical toxaphene may be discriminated and/or degraded differently than toxaphene compounds in environmental samples when using SSL. This resu lts in significant bias of the quantitative data when using the technical m aterial as a reference. OC suffers much less from these deficiencies and, t herefore, is a preferable technique for toxaphene analysis. (C) 2000 Elsevi er Science Ltd. Ail rights reserved.