Development of polymethylphenylsiloxane-coated fiber for solid-phase microextraction and its analytical application of qualitative and semi-quantitative of organochlorine and pyrethroid pesticides in vegetables.

An approach to the synthesis of hydroxyl-terminated polymethylphenylsiloxane (PMPS-OH) was proposed and the synthesized PMPS-OH was successfully applied as a precursor to prepare a novel coating for solid-phase microextraction (SPME) via the sol-gel process. The thickness and length of the prepared coating was 70 microm and 1.5 cm, respectively. The extraction efficiency of the PMPS-coated fiber for selected pesticides was higher than that of commercial fibers including 100 microm polydimethylsiloxane (PDMS), 85 microm polyacrylate (PA) and 65 microm polydimethylsiloxane/divinylbenzene (PDMS/DVB). The influence of the extraction process, extraction temperature, extraction time, stirring rate, ionic strength, GC inlet conditions, desorption temperature and time for PMPS-coated fiber application was studied and optimized. Several experiments were carried out to evaluate the analytical characteristics of the proposed SPME-GC-ECD method under optimized conditions. The linearity was from 0.5 to 100 ng g(-1) for p,p'-DDE, p,p'-DDD and bifenthrin, and from 2 to 100 ng g(-1) for o,p'-DDT, p,p'-DDT, fenpropathrin, beta-cyfluthrin and cyhalothrin. The detection limits of these pesticides were between 0.13 and 1.45 ng g(-1). The recovery of the pesticides spiked in various vegetables at 4 ng g(-1) ranged from 42.9% to 105.3%, and the relative standard deviations were less than 16.2%.