时间分辨荧光免疫分析方法检测烟草中菌核净残留

摘要

A sensitive time-resolved fluorescence immunoassay (TRFIA) with a cleanup-free pretreat-ment for dimethachlon in tobacco was developed The competitive indirect TRFIA for dimethachlon was established by using goat anti-rabbit IgG conjugated with a Eu-N1 delate as a tracer. The detection limit ( I10) and I50 for this assay was 1. 98 μg/L and 32. 00 μg/L, respectively. And the linear range for detection is between 3. 97 -128. 76 μg/L. Meanwhile, the effect of tobacco matrix to TRFIA was also studied. It was demonstrated that the linear range of inhibition curve with 1 % tobacco matrix was parallel to the standard curve; so the extract of tobacco would be diluted 200 times before assay, the index of matrix interference (Im) was calculated as 17. 1. Three levels of dimethachon (1,7 and 24 mg/L) were spiked into tobacco, the overall recoveries and the relative standard deviations (RSDs) were in the range of 73%-128% and 4. 3 -13. 2, and the practical detection limit for the method was 1 mg/L. This assay is a suitable tool for screening dimethachlon residue in tobacco samples%建立了简便、灵敏地检测烟草中菌核净残留的时间分辨荧光免疫分析方法(TRFIA),及配套的无净化的快速前处理技术.采用镧系元素螯合物Eu-N1标记亲和纯化后的羊抗兔IgG示踪抗体.采用间接竞争TRFIA法建立了菌核净标准抑制曲线,方法的检出限为2.0 μg/L;抑制终浓度I30为32.00 μg/L;检测线性范围为4～128 μg/L.考察了丙酮提取后33％,10％和1％的烟草基质对菌核净-TRFIA分析方法的影响,表明在1％烟叶基质条件下,建立的菌核净的抑制曲线的线性范围与标准抑制曲线趋于平行,确定烟草样品的前处理稀释倍数为100倍,计算得到基质影响因子(Im)为17.1.对烟叶样品中添加1,7和24 mg/L的菌核净标样,连续3d的添加回收实验表明,方法的回收率为73％～128％,相对标准标准偏差(RSD)在4.3％～13.2％之间；烟草中菌核净的实际最低检出限为1 mg/L.本方法可望用于烟草中菌核净残留的快速筛选检测.