Comparison of gas and liquid chromatography for analysing polar pesticides in water samples

Abstract

This review describes the applications of gas chromatography (GC) and liquid chromatography (LC) in the analysis of selected groups of pesticides in water. The attention is focussed on the most popular (in terms of amounts produced and applied) pesticide classes, i.e., carbamates, phenylureas, triazines, phenoxy acetic acid derivatives and chlorinated phenols. The use of GC and LC for the analysis of these compounds in water samples in the past and at present is reviewed separately for each group. Sample concentration and detection techniques are discussed in relation to their influence on the performance of the particular separation technique. Special attention is given to mass spectrometry (MS) because it is the most intensively developed detection technique in environmental analysis. The potential of another novel approach - large volume injections into the GC - is discussed separately. Methods using GC or LC coupled to an appropriate detector and using suitable sample handling procedures provide detection limits typically in the range of 0.001–1 ppb. At these levels, target or unknown compounds can be determined/identified by means of their retention and spectral characteristics. Principally, most of the analytes can be determined by both techniques, however, GC methods, when applicable, still have the advantages of great separation efficiency, high speed of analysis and the availability of a wide range of highly sensitive detectors; on the other hand, LC is often a method of choice when polar, non-volatile or thermolabile compounds are to be analyzed. Neither of the two separation techniques reviewed seems to have an overall priority in environmental analysis of pesticides. They can be considered as complementary.