酶速测法检测茭白中农药残留的假阳性消除方法

Method for eliminating false positive results of pesticide residues in zizania by enzyme speed method

中文关键词:  假阳性  快速检测  茭白  农药残留

英文关键词:false positive results  rapid testing  zizania  pesticide residue

中文摘要:

      目的 建立一种能有效减小茭白中植物次生质对胆碱酯酶活性的影响的前处理方法。方法 将样品经高温水浴热处理后酶速测法检测, 通过比较水浴热处理前后酶抑制率的差异评价该方法的有效性。同时对18种具有代表性的机磷类农药或氨基甲酸酯类农药进行热稳定性实验和验证实验。结果 实验结果表明能最有效地消除茭白基质中假阳性发生的最佳前处理条件是水浴温度90 ℃、热处理7 min。18种具有代表性的机磷类农药或氨基甲酸酯类农药热稳定性实验和验证实验结果表明在最佳实验条件下, 大部分有机磷类和氨基甲酸酯类农药不发生受热分解, 小部分农药(抗蚜威、甲基毒死蜱和对硫磷)易受热分解。结论 该前处理方法对热稳定性强的农药能有效消除或减少茭白中假阳性的发生, 但对少部分热稳定性差的农药并不一定能消除假阳性, 甚至由于易受热分解, 导致出现假阴性的检测结果。该方法简单、低成本, 对于现场快速检测具有重要的意义。

英文摘要:

      Objective To establish a pretreatment method to reduce the plant secondary substance in zizania on cholinesterase activity. Methods The samples were treated by high temperature water bath and detected by enzyme rapid detection method. The effectiveness of the method was evaluated by comparing the difference of enzyme inhibition rate before and after water bath heat treatment. At the same time, thermal stability and validation experiments were carried out on 18 representative organophosphorus pesticides or carbamate pesticides. Results The results showed that the optimum pretreatment condition to eliminate the false positives in zizania matrix was to preheat the sample on water bath at 90 ℃ for 7 min. From thermal stability experiments and verifying experiments with 18 kinds of typical organophosphorus pesticides and carbamate pesticides aqueous solutions, the results showed that under the optimum pretreatment condition, thermal decomposition did not happen in most organophosphorus and carbamate pesticides, only in small fraction of pesticides (pirimicarb, chlorpyrifos-methyl and parathion). Conclusion This pretreatment method can effectively eliminate or reduce the false positive results in water shoot with high thermal stability, but it is not certain to eliminate false positives in a small number of pesticides with low thermal stability, or even lead to false negative test results due to their easy thermal decomposition. This method is simple and low cost, which has great significance for on-site rapid detection.