Matrix effects and selectivity of the detector in the determination of butyl- and phenyltins by gas chromatography flame photometric detection

Two main types of matrix effects were observed during the analysis of environmental samples by ethylation with sodium tetraethylborate-gas chromatography-flame photometric detection: the first one was a disturbance of the GC signal such as baseline discontinuity or decrease of photometric emission and the second one variations of the organotin responses. For the GC signal, organic matter dissolved after acidic extraction was found to be mainly responsible. It was possible to reduce these effects significantly by the removal of organic matter by centrifuging and pH control. The variations of the organotin responses were more difficult to resolve. But it was possible to obtain a reliable quantification using simultaneously standard addition and internal standard methods. The flame photometer appeared sufficiently selective in regard to other selective detectors. However, it was confirmed that sulfur compounds could give a photometric signal at 610 nm. This emission was not a problem for organotin quantification because no coelution of interfering species and analytes was observed. The application of this method to different complex samples such as sediments, biota or sewage sludge has finally confirmed its suitability for pollution control in the environment. (C) 1998 Elsevier Science B.V. All rights reserved.