Thermospray liquid chromatographic—mass spectrometric multi-residue determination of 128 polar pesticides in aqueous environmental samples

Thermospray (TSP) ionization was evaluated with respect to its suitability in the LC-MS determination of a broad range of pesticides. The sensitivity and the selectivity of this method for the determination of 128 pesticides having a wide range of structures and polarities were investigated. An LC separation in combination with postcolumn addition of a volatile salt solution was developed, which permits the analysis of 95 pesticides with a single LC-MS method using reversed-phase gradient caution. The retention data and TSP mass spectra of these compounds are presented. The advantages of TSP postcolumn techniques in comparison with conventional systems are discussed. The application of this method to the analysis of an environmental sample (river water) spiked with eight phenylureas is demonstrated. lie method was evaluated with respect to detection limit, linearity and reproducibility. In addition, a simple method for enhancing the structural information from TSP spectra is reported, which makes use of specific instabilities found with many pesticides. As an example, possibilities for the confirmatory analysis of carbamates are described.