Comparison of solid phase microextraction and hollow fiber liquid phase microextraction for the determination of pesticides in aqueous samples by gas chromatography triple quadrupole tandem mass spectrometry

This work compares two miniaturised sample preparation methods, solid phase microextraction (SPME) and hollow fiber liquid phase microextraction (HF-LPME), in combination with gas chromatography coupled to tandem mass spectrometry with a triple quadrupole analyzer for the determination of 77 pesticides in drinking water. In the case of SPME, extraction temperature and time were optimized by experimental design, although other parameters, as desorption time, pH, and ionic strength, were also evaluated. The extraction and desorption solvents [octanol/dihexyl ether (75:25, v/v) and cyclohexane, respectively], as well as the extraction and desorption time, ionic strength, and pH, were studied for the HF-LPME procedure. Under the optimal conditions, recoveries (70.2-113.5% for SPME and 70.0-119.5% for HF-LPME), intra-day precision (2.1-19.4% for SPME and 4.3-22.5% for HF-LPME), inter-day precision (5.2-21.5% for SPME and 8.4-27.3% for HF-LPME), and limits of detection, between 0.1 and 28.8 ng/L for SPME and 0.2 and 47.1 ng/L for HF-LPME and overall uncertainty (9.6-25.2% for SPME and 13.3-27.5% for HF-LPME) were established for both extraction procedures. Finally, the proposed methods were successfully applied to the analysis of 41 drinking water samples, and similar results were obtained with both extraction approaches.