| Summary: | 碩士 === 中原大學 === 生物醫學工程研究所 === 104 === Pesticide is the most economical and convenient method of pest control, but it will cause environmental pollution and toxic residues in crops when using the wrong method. Traditional methods are gas chromatography or high performance liquid chromatography coupled to mass spectrometry. However, these methods require long work up time and expensive instrumentation. Aim of this study is to develop a fast, easy pesticides sensor which can detect field samples immediately. By the property of pesticides inhibiting AChE activity, we use electrochemical technology for pesticides analysis in which the enzyme activity is employed as an indicator of quantitative measurement of insecticides. The results of electrochemical workstation analysis verify that the screen-printed electrode used in this study has good stability and the ability to detect enzyme. Furthermore, this study reduces oxidation potential by addition of hexacyanoferrate as the redox mediator. Then through comparison of the results of electrochemical workstation analysis and homemade sensor confirmed that homemade sensor has the ability for AChE activity monitoring. This study used the carbamate pesticide carbaryl to detect pesticides. The result shows 0.1 U of AChE would be inhibited to 61 % of residual enzyme activity at 3 min of pesticides inhibition time by 2 ppm of carbaryl. In the calibration curve of standard pesticides, it can be seen that the activity of AChE decreased with the increase of carbaryl concentration. The linear portion of the curve with carbaryl concentrations range is from 0.1 to 2 ppm, and R2 = 0.99844. This result is in compliance with norms of Taiwan Food and Drug Administration for carbaryl residue tolerance in different types of crops. However, we found that the pesticide extract of cabbage contains interfering substances in real sample analysis. The result shows that we still could distinguish the different concentrations of pesticides for different degree of inhibition of enzyme activity, but the error bar of detection would increase, and the degree of inhibition of enzyme activity would be worse. In the future, we hope we can increase the specificity of the enzyme reaction or further reduce the oxidation potential of detection to reduce the influence caused by interfering substances in real sample analysis.
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