甲硫醇离子选择性电极的研制及其在甲胺磷残留量测定中的应用

Preparation of Methylthioalcohol Ion-selective Electrode and Its Application to Determination of Methamidophos Residue

本文以甲硫醇银及硫化银为电活性材料制得对甲硫醇离子有选择性响应的固态膜离子选择性电极。在pH为9.3的0.035mol/L Na_2B_4O_7-0.1mol/L NaOH-0.1mol/L Na_2SO_3介质中,电极的线性响应范围为5×10^(-6)～1×10^(-2)mol/L,响应斜率为58mV/pX。蔬菜中甲胺磷的残留量可以用乙酸乙酯或甲醇水溶液提取后,利用其在碱性条件下水解生成甲硫醇离子的特性用本电极测定,检测限2μg/g,设备简单,操作方便。

A methylthioalcohol solid state membrane ion selective electrode with CH_3SAg and Ag_2S as electroactive materials was prepared. This electrode exhibited a linear response to the methylthioalcohol ion within the concentration range of 5×10^(-5)～1×10^(-2)mol/L with a responce slope of 58 mV/pX, in the buffer solution of 0.035mol/L Na_2B_4O_7-0.1 mol/L NaOH-0.1 mol/L Na_2SO_3 at pH 9.3. After extraction of methamidophos in vegetable samples with ethyl acetate or methanol-water solution and hydrolytic decomposition of methamidophos with NaOH, the methamidophos residue in the vegetable can be ascertained by means of the methylthioalcohol ion-selective electrode. The detection limit is 2 ppm. The equipments are simple and the procedure is convenient.