Solid-phase micro-extraction-gas chromatography-(tandem) mass spectrometry as a tool for pesticide residue analysis in water samples at high sensitivity and selectivity with confirmation capabilities.

Gas chromatography-mass spectrometry (GC-MS) has been widely applied for pesticide monitoring because of its high sensitivity and specificity and for the potential of multi-residue and multi-class analysis. An analytical procedure was developed for the determination of pesticide multi-residues in water samples combining solid-phase micro-extraction (SPME) and gas chromatography-ion trap mass spectrometry. For SPME extraction a poly(dimethylsiloxane)-divinylbenzene coated fibre was selected whereas the mass spectrometer was operated under full scan, selected ion storage (SIS), microSIS (SIM) and MS-MS and the figures of merit compared. Quantitative and qualitative (confirmatory) capabilities of each operation mode are discussed. Using MS-MS, precision was typically below 10% and limits of detection (LODs) were improved by 1.3 to 20 times (to low- or sub-ppt levels) compared to microSIS, with the advantage of maintaining identification capabilities. The combination of selective extraction by SPME and highly selective determination by GC-MS-MS made possible ultra-selective and essentially error-free determination of pesticides in complex environmental samples. This aspect will be highlighted in the paper.