基于FIA和光学原理的酶传感器检测海水甲基对硫磷

Detection of Methyl-Parathion in Seawater with an Enzyme Sensor Based on FIA and Colorimetric Principle

将乙酰胆碱酯酶（acetylcholinesterase，AChE）传感器与流动注射系统（flow injection analysis system，FIA）相结合，通过光学方法测定固定化酶受农药抑制后的残余活性，对海水中微量甲基对硫磷进行定量分析。该系统的适宜工作条件为：温度30℃；固定化酶的用量0．05u；载液流速0．45mL／min；进样时间20min；底物（碘化硫代乙酰胆碱）溶液浓度0．100mol／L，注射量100μL。在0．1～100μg／L之间，农药浓度的对数值与固定化酶活性的抑制率之间具有良好的线性关系（r=0．9953）。利用该系统检测含甲基对硫磷分别为0．8μg／L和5．0μg／L的模拟海水样品，获得了较好的准确度和精密度，平均相对误差和变异系数均小于10％。

An AChE biosensor, connected with a flow injection analysis system （FIA）, was derigned to detect methyl-parathion in seawater rapidly, by colorimetric determination of the activity change of the immobilized AChE from the organophosphorus pesticide. The working conditions for this system were optimized as follows： the temperature was 30℃ ; the dosage of immobilized AChE in the reactor was 0.05 U; the flow rate was 0.45 mL/min for both the carrier and the samples, the inhibition time from the samples lasted for 20 rain; the concentration and injection volumes of the substrate and the acetylthiocholine iodide were 0. 100 mol/L and 100 μL respectively. Linder these conditions, the percent inhibition of the immobilized AChE increased with the concentration of methyl-parathion in seawater. For the samples with methyl-parathion from 0.1 μg/L to 100 μg/L, there was a good linearity （r = 0. 995 3） between the biosensor response and the logarithm of methylparathion concentration. When the system was used to measure the samples containing 0.8μg/L and 5.0μg/L methyl-parathion, better accuracies and precisions were obtained, both the average relative error and the RSD were less than 10 %