Novel unbreakable solid-phase microextraction fibers on stainless steel wire and application for the determination of oxadiargyl in environmental and agricultural samples in combination with gas chromatography-mass spectrometry.

Sol-gel based solid-phase microextraction fibers supported by a stainless steel wire were fabricated and employed for GC-MS determination of oxadiargyl in real samples. The fibers were based on four compounds with different polarity: polar and non-polar (end-capped) poly(dimethylsiloxane) (PDMS), polyethylene glycol (PEG), and poly(ethylene-propyleneglycol)-monobutyl ether (UCON). For this purpose, the surface of the stainless steel was initially modified by (3-mercaptopropyl) trimethoxysilane. The results of the modification procedure were evaluated by cyclic voltammetry and energy dispersive X-ray (EDX) spectroscopy. After the modification, four different sol-gel based SPME fibers with different values of polarity, polar and non-polar PDMS, PEG, and UCON have been prepared and investigated. They are supposed to be employed to determinate oxadiargyl in agricultural and environmental samples prior to gas chromatography-mass spectrometry analysis. Most important parameters that affect the extraction efficiency were also optimized. Under optimized conditions, the proposed method was found to be linear for the concentrations ranging from 100 ng L(-1) to 2 mg L(-1) with R(2)=0.997. Limit of detection (LOD) of 40 ng L(-1) and relative standard deviation of less than 10% were obtained. Relative recovery in environmental and agricultural samples was in the range of 73-96%.