Green capsule phase microextraction employing hydrophobic monolithic sol-gel octadecyl siloxane platforms for the monitoring of organophosphorus pesticides in environmental water samples

In this study, a novel, facile and green capsule phase microextraction (CPME) method is presented for the extraction and preconcentration of organophosphorus pesticides (i.e., chlorpyrifos, disulfoton, ethoprophos, fenchlorphos, prothiofos, and parathion-methyl) from environmental water samples. Monolithic sol-gel octadecyl siloxane (sol-gel C18) sorbent encapsulated within porous polypropylene capsules was synthesized, characterized, and evaluated for its efficiency towards the adsorption of the target organophosphorus pesticides. CPME was combined with gas chromatography-mass spectrometry (GC-MS) for the monitoring of the target analytes. The method was optimized to ensure high method sensitivity and it was fully validated. The limits of detection of the CPME-GC-MS method for the OPPs were 0.02–0.15 ng mL−1. The relative standard deviations were 1.5–8.7% for intra-day study and 5.4–9.6% for inter-day study, demonstrating satisfactory precision. Moreover, good method accuracy was obtained, since the relative recoveries were within the range 92.6–107.0% and 90.8–107.6% for intra-day and inter-day (c = 5.00 and 20.0 ng mL−1), respectively. The absence of interferences in the blank samples demonstrates that the proposed method is selective. The sol-gel C18 sorbent encapsulated CPME media could be reused for at least 25 adsorption/desorption cycles. In addition, the methodology presents advantageous features in comparison to existing methods. The final protocol was used for analyzing four different water sample types (i.e., lake water, river water, pond water and tap water sample).