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在pH7.0的磷酸盐缓冲溶液中,硫代黄素T与乙酰胆碱酯酶相互作用,酶的内源荧光被硫代黄素T猝灭,而在490nm处产生硫代黄素T的特征荧光发射峰。在该体系中加入有机磷农药对氧磷后,硫代黄素T的特征荧光峰被猝灭,荧光猝灭强度ΔF与对氧磷浓度CPx存在线性关系,其线性浓度范围为0.20~2.40mg/L,回归方程为ΔF=0.041CPx(μg/L)+84.17,相关系数为0.9984,检出限(3σ)为7.87μg/L。对检测原理的探讨表明,硫代黄素T使乙酰胆碱酯酶内源荧光静态猝灭,二者形成了超分子复合物,产生了特征荧光峰;但是,有机磷农药对氧磷可破坏此复合物,因而硫代黄素T的特征荧光峰被猝灭。相比利用酶的抑制原理来检测农药残留的方法,该方法具有简便、快速、不需要消耗酶的底物的优点。
In pH 7.0 phosphate buffer solution, thioflavin T interacts with acetylcholinesterase, the endogenous fluorescence of the enzyme is quenched by thioflavin T, and the characteristic fluorescence of thioflavin T is produced at 490 nm Emission peak. The characteristic fluorescence peak of thioflavin T was quenched after adding organophosphorus pesticide paraoxon to the system. The fluorescence quenching intensity ΔF had a linear relationship with the paraoxon concentration CPx. The linear range was 0.20-2.40 mg / L, the regression equation was ΔF = 0.041CPx (μg / L) +84.17, the correlation coefficient was 0.9984, and the detection limit (3σ) was 7.87μg / L. The investigation of the detection principle shows that thioflavin T causes the endogenous fluorescence of acetylcholinesterase to be quenched statically, and the two forms a supramolecular complex, resulting in a characteristic fluorescence peak. However, the organophosphorus pesticide on oxygen and phosphorus can destroy this composite Thus, the characteristic fluorescence peak of thioflavin T is quenched. This method has the advantage of being simple, rapid and requires no enzyme consuming substrate, as compared to the method of detecting pesticide residues using the principle of enzyme inhibition.