生物活性膜复合修饰电极安培法测定痕量光合抑制类除草剂

Amperometric Determination of Trace Amount of Photosynthesis-Inhibiting Herbicides Using a Composite Modified Electrode with Bioactive Membrane

根据除草剂对类囊体膜光合作用光系统II (PSII)的抑制效应 ,利用聚乙烯醇 -苯乙烯吡啶 (PVA SbQ)光聚合法固定类囊体膜 ,结合普鲁士蓝修饰电极对过氧化氢电还原的高灵敏、高选择性的催化作用 ,制成了用于安培法检测除草剂残留的生物活性膜修饰电极 .电极通过测量加入除草剂时类囊体膜光合作用产生过氧化氢的活性变化 ,对除草剂进行测定 .在含有 1 5× 10 -3 mol/LNaCl和 5× 10 -3 mol/LMgCl2 的pH =6 8磷酸盐缓冲溶液中 ,测量 0 0 5V处过氧化氢的还原电流的变化可以分别测定不同浓度的除草剂 ,检出限分别为敌草龙 3 6× 10 -9mol/L ,阿特拉津 6 1× 10 -9mol/L ,敌稗 8 7× 10 -9mol/L .普鲁士蓝作为电子中介体 ,显著增大了测定的灵敏度 .

A composite modified electrode with biomembrane was prepared for amperometric detection of herbicide, which was based on the photosynthesis-inhibiting effect of certain herbicides on photosystem II of chloroplast thylakoid. The thylakoid membrane isolated from spinach leaves was entrapped in polyvinylalcohol bearing styrylpyridinium groups (PVA-SbQ). The membrane was then fixed on the head of the Prussian blue-modified carbon paste electrode. Reductive catalytic current of hydrogen peroxide was detected at 0.05 V in pH 6.8 phosphate buffer solution containing 1.5x10(-3) mol/L NaCl and 5x10(-3) mol/L MgCl2. In the presence of herbicides, the concentration changes of hydrogen peroxide produced by photosynthesis-inhibiting were observed, and the corresponding current changes were in proportion to their inhibitory effects. The electrode allowed to detect the herbicides in the concentration ranges of 1x10(-8)similar to1x10(-6) mol/L for diuron, 2x10(-8)similar to1x10(-6) mol/L for atrazine and 5x10(-8)similar to1x10(-6) mol/L for propanil with detection limits of 3.6x10(-9), 6.1x10(-9) and 8.7x10(-9) mol/L, respectively. The sensitivity of the electrode was improved remarkably due to the incorporation of the electron-mediate of Prussian blue.