Sol-gel/nanoclay composite as a solid-phase microextraction fiber coating for the determination of organophosphorus pesticides in water samples.

A novel solid-phase microextraction (SPME) fiber coated with a sol-gel/nanoclay composite was prepared by the sol-gel technique involving the hydrolysis reaction of alkoxysilanes and the subsequent condensation reaction with hydroxyl groups of the nanoclay on a stainless steel wire. A method based on direct immersion SPME and gas chromatography-corona discharge ion mobility spectrometry was developed for the determination of four organophosphorus pesticides in aqueous samples. The effect of different experimental parameters on the extraction efficiency of the method was investigated. The sol-gel/nanoclay fiber showed higher extraction performance for the organophosphorus pesticides compared with Ppy/nanoclay, sol-gel coating, and three commercial fibers (polydimethylsiloxane (PDMS), PDMS/divinylbenzene (DVB), and polyacrylate (PA)). Limits of detection (LOD) and quantitation (LOQ) of the method were in the range of 0.003-0.012 and 0.01-0.02 μg L(-1), respectively. The calibration curves were linear in a concentration range from 0.01 to 2.0 μg L(-1) (r (2)  > 0.995). The relative standard deviations for intra- and inter-day precision were 3.3-5.6 and 6.4-8.4 %, respectively. Fiber-to-fiber reproducibility for three prepared fibers was 7.4-10.2 %. Finally, the method was successfully applied for the extraction of the studied compounds from water samples. The relative recovery obtained for the spiked real-water samples were 86-104 %.