Abstract:

A novel method for the determination of organophosphorous pesticides (OPPs) in fresh juice samples was developed. Fe₃O₄@P(St-co-MAA) magnetic microparticles were synthesized and modified with styrene (St) and methacrylic acid (MAA) by coating St and MAA on magnetic particles and characterized by a series of techniques. The results indicated that Fe₃O₄ magnetic nanoparticles (MNPs) have been successfully modified with St and MAA. Based on the prepared Fe₃O₄@P(St-co-MAA) magnetic microparticles, a novel method of magnetic solid phase extraction (MSPE)-gas chromatography (GC)-flame photometric detection (FPD) was developed for the determination of OPPs. The extraction/desorption conditions of MSPE were optimized, and the analytical performance was evaluated under the optimal conditions. The limits of detection (LODs, S/N=3) for target OPPs were in the range of 0.013-0.305 μg/L with the RSDs (n=7) ranging from 3.1% to 8.8%. The enrichment factors varied from 406 to 951. The linear ranges were over three orders of magnitudes (R²>0.99) and the reproducibilities were 7.4%-14.5% (n=5). Finally, the proposed MSPE-GC-FPD method was successfully applied to the analysis of the five OPPs in fresh tomato and strawberry juice samples, with the recoveries of target OPPs in the range of 85.4%-118.9% for the spiked samples. The proposed MSPE-GC-FPD method is featured with low cost, fast separation and high enrichment factor.

Key words: gas chromatography-flame photometric detection (GC-FPD), juices, magnetic solid phase extraction (MSPE), organophosphorus pesticides (OPPs)