Comparison of hollow fiber liquid phase microextraction and dispersive liquid-liquid microextraction for the determination of organosulfur pesticides in environmental and beverage samples by gas chromatography with flame photometric detection.

Two methods based on hollow fiber liquid phase microextraction (HF-LPME) and dispersive liquid-liquid microextraction (DLLME), have been critically compared for the analysis of organosulfur pesticides (OSPs) in environmental and beverage samples by gas chromatography-flame photometric detection (GC-FPD). Experimental conditions including extraction solvent, solvent volume, extraction time, temperature and ionic strength have been investigated for both HF-LPME and DLLME. Under the optimal conditions, the limits of detection for the six target OSPs (malathion, chlorpyrifos, buprofezin, triazophos, carbosulfan and pyridaben) obtained by HF-LPME-GC-FPD and DLLME-GC-FPD were ranged from 1.16 microg/L to 48.48 microg/L and 0.21 microg/L to 3.05 microg/L, respectively. The relative standard deviations (RSDs, n=5) were in the range of 3.4-8.0% and 8.5-13.7%with the enrichment factors (EFs) of 27-530 and 176-946 folds for HF-LPME-GC-FPD and DLLME-GC-FPD, respectively. Both methods were found to be simple, fast, efficient, and inexpensive. Compared with HF-LPME, the advantages of DLLME technique were less extraction time, suitable for batches of samples pretreatment simultaneously, a higher extraction capacity when analyzing simple samples such as water samples. While for the analysis of complicated matrix samples such as soil and beverage samples, HF-LPME was demonstrated to be more robust and more suitable. Both methods were applied to the analysis of six OSPs in different waters, soil and beverage samples, and no target OSPs was found in these samples. For analysis of the spiked samples, the recovery of 81.7-114.4% with RSDs of 0.6-9.6% were obtained for HF-LPME, and the recovery of 78.5-117.2% with RSDs of 0.6-11.9% were obtained for DLLME.