检测吡虫啉的极谱分析方法研究

Determination of Imidacloprid by Polarography

本文利用吡虫啉(Imidacloprid,IMI)在Na2HPO4-NaH2PO4缓冲溶液(PBS,pH=8.0)与1.0×10^-3mol/L十二烷基磺酸钠(SDS)的底液中,能够产生一个灵敏的还原峰,从而建立了一种测定农作物中吡虫啉农药残留的极谱分析新方法。实验于起始电位-0.40V(vs.SCE),以700mV/s扫描,在峰电位-1.10V左右(vs.SCE),吡虫啉浓度分别在2.0×10^-6~2.8×10^-5mol/L和2.8×10^-5~1.24×10^-4mol/L的范围内与其峰电流成线性关系,检出限为1.02×10^-7mol/L。该方法直接用于农作物中吡虫啉残留测定,加标回收率为92.7%~109.2%。用单扫描极谱法研究了检测体系的电化学行为,实验证明极谱波为不可逆还原吸附波。初步探讨了电极反应机理。

A new polarographic method for the determination of imidacloprid(IMI) residues in crops was established. It based on the sensitive reduction peak generated by IMI in Na2HPO4-NaH2PO4(PBS)(pH=8.0) buffer solution and 1.0×10-3 mol/L sodium dodecyl sulfate(SDS). Under optimized condition, the initial potential was-0.40 V(vs.SCE) and the peak potential was about-1.10 V(vs, SCE) by polarography. The peak current is linearly proportional to the concentration of IMI over the range of 2.0×10-6-2.8×10-5 mol/L and 2.80×10-5-1.24×10-4 mol/L, the detection limit is 1.02×10-7 mol/L. The method was used for the detection of the residual content of IMI in crops. The recovery of the samples was 92.7%-109.2%. The electrochemical behavior of the detection system was investigated by single-sweep polarography. The experimental results indicate that the polarographic wave is an irreversibly reduced adsorption wave, and the reaction mechanism of the electrode was discussed.