磁固相萃取-气相色谱-火焰光度检测联用测定果汁中的有机磷农药

制备了苯乙烯（St）和甲基丙烯酸（MAA）共聚物改性的磁性微球Fe₃O₄@P（St-co-MAA），并将其作为磁固相萃取吸附剂，建立了磁固相萃取（MSPE）-气相色谱（GC）-火焰光度检测（FPD）联用分析有机磷农药（OPPs）残留的新方法。以5种有机磷农药（二嗪农、甲基毒死蜱、杀螟硫磷、毒死蜱和喹硫磷）为目标分析物，考察并优化了吸附和解吸条件，确定了最佳实验条件。在最优的实验条件下，方法对5种OPPs的检出限（S/N=3）为0.013~0.305 μg/L，方法的相对标准偏差（RSD，n=7）为3.1%~8.8%，富集倍数为406~951，线性范围达3个数量级。将该方法应用于新鲜番茄汁、草莓汁样品中的OPPs残留分析，加标回收率为85.4%~118.9%。该方法具有检出限低、分析速度快、富集倍数高等优点，为有机磷农药的残留分析提供了新的技术平台。

Magnetic solid phase extraction combined with gas chromatography-flame photometric detection for the determination of organophosphorus pesticides in juice samples

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.