In vivo investigation of pesticide residues in garlic using solid phase microextraction-gas chromatography-mass spectrometry.

In this study, a novel multiwalled carbon nanotubes/polyaniline-polypyrrole@polydimethylsiloxane (MWCNTs/PANI-PPy@PDMS) fiber was prepared by a facile electrodeposition strategy followed by polymer surface modification, and used as the sorbent of in vivo solid phase microextraction (in vivo SPME). The custom-made fiber exhibits better enrichment capacity than three commercial SPME fibers. Ultra-high enrichment factor (438-2659), satisfactory thermal and mechanical stability, excellent matrix-compatibility and anti-biofouling ability render the fiber attractive as in vivo sampling probe. Combining in vivo SPME with gas chromatography-mass spectrometry (GC-MS), a convenient and sensitive method was successfully developed for the rapid determination of pesticides (hexachlorobenzene, chlorothalonil, fipronil, chlorfenapyr) in garlic. Under the optimal conditions, the proposed method displays relatively wide linear range (three or four orders of magnitude) with a coefficient of determination above 0.9944 both in the standard solution and spiked homogenized garlic samples, respectively. Low detection limits from 0.38 to 1.90 ng g-1 were obtained in homogenized garlic samples. Relative standard deviations (RSDs) less than 15.5% and recovery between 84.0% and 108.2% indicate satisfactory precision and accuracy of the method. In summary, a promising non-lethal method based on in vivo SPME-GC-MS is developed in this study, which provides a green, efficient, economic and rapid strategy for the determination of trace pesticide residues in edible plants.