Résumé
Porous carbon nanoparticles ( NPC) were prepared by ZnCl2 activation and carbonization using citrus waste as carbon source. A sample pretreatment method with NPC as dispersive solid phase extraction (d-SPE ) absorbent was established for the determination of organophosphorus pesticides in fruits and vegetables by gas chromatography. The NPC was characterized by scanning electron microscopy (SEM), X-ray diffraction ( XRD), FT-IR spectra, Raman spectroscopy, Brunauer, Emmett and Teller surface area(BET). Those results showed that the NPC was an amorphous porous carbon material with pore size in the range of 0-15 nm. Its specific surface area and pore volume were 1243 m2 / g and 1. 28 cm3 / g, respectively. The analysis conditions, including the amount and clean up time of adsorbent, were optimized by analysis of 14 kinds of oranophosphorus pesticides in fruits and vegetables with gas chromatography-flame photometric determination(GC-FPD). Moreover, the comparison for NPC with commercial materials of PSA, C18 and GCB was investigated in this study. The results indicated that the purification time was only 2 min using 0. 01 g NPC. The cost of NPC was about 25% of C18 , 21% of PSA and 16% of GCB. Because of the porous structure of NPC, the purification efficiency was significantly higher than the three commercial materials mentioned above. Under the optimum conditions, the calibration curves of the 14 organophosphorus pesticides were linear in the range of 0. 02-1. 00 mg / L with good correlation coefficients (R2>0. 99) and detection limits (S / N=3) of 0. 63-5. 30 μg / kg. The recoveries of the pesticides at three spiked levels ranged from 71. 3% to 114. 7%with the relative standard deviations (RSDs) of 0. 9% -12. 9% . The method is simple, rapid, sensitive, and low cost, and can satisfy the requirements of detection of organophosphorus pesticide residues in fruits and vegetables, displaying a good application prospect.