- 學位論文
農藥殘留快速檢測與電化學感測器開發
Development of electrochemical device for rapid determination of residual pesticides based on AChE
摘要
農藥是目前最經濟且便利的病蟲害防治方法，但是使用不當時會造成環境汙染及作物的毒性殘留。傳統之農藥檢測方法不外乎是使用氣相層析儀或是高效液相層析儀串聯質譜儀進行檢測，這些分析技術雖然有很高的精準度與靈敏性，但是其檢測相當耗時，使用的儀器往往都龐大且昂貴。因此本研究希望開發出一個快速、方便且可以實地檢測樣品的農藥感測器，藉由有機磷及氨基甲酸鹽農藥會抑制乙醯膽鹼酯酶活性的特性，以電化學的方式偵測酵素的活性，間接定量農藥的含量。本研究藉由電化學儀的分析，確認本研究使用之空白石墨網版印刷電極具有良好的穩定性及檢測酵素活性的能力，並以鐵氰化鉀作為電子媒介物降低氧化電位。透過電化學儀的分析結果與自製感測器比較，證實自製感測器能夠有效偵測乙醯膽鹼酯酶的活性。在農藥檢測中，本研究以氨基甲酸鹽類農藥加保利進行實驗。農藥抑制時間影響的結果得知3分鐘的抑制時間便有非常顯著的效果，2 ppm的加保利可以抑制0.1 U的乙醯膽鹼酯酶至61 %的殘餘活性。標準農藥抑制曲線的檢測結果顯示，乙醯膽鹼酯酶的活性會隨著農藥濃度的提高而降低，檢測線性範圍為0.1 ~ 2 ppm，R2 = 0.99844。此結果符合衛生福利部食品藥物管理署對於加保利於不同作物的農藥殘留容許量標準之規範，但在實際樣品分析中，發現小白菜的農藥萃取液含有有干擾農藥分析的物質，雖然仍可以分辨不同濃度之農藥對於酵素活性的抑制程度不同，但是檢測的誤差值增加，酵素活性的抑制效果相對於標準農藥也變差。未來期許能夠增加酵素反應的專一性或是進一步降低氧化工作電位，改善實際樣品分析中干擾物對於分析結果的影響。
並列摘要
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.