農藥殘毒快速檢驗技術之研發

Abstract

為因應快速運銷鮮食蔬果之農藥殘毒檢驗問題，台灣省農業試驗所補充現行精密但耗時之化學檢驗技術，改依毒理學基礎，製備對農藥敏感之酵素或微生物，開發快速檢測農藥殘毒技術。該體系結合生物性探針酵素反應、光譜分析及化學薄層分析等方法，研製成功「蔬果農藥殘毒快速檢驗」技術，可檢驗（l ）具神經毒性之殺蟲劑－有機磷及氨基甲酸鹽劑及（2 ）有機硫磺劑及其他數類殺菌劑。分析的層次已可由毒性之檢測，以至快速追蹤定性及定量。 快速檢驗之研發始於民國70 年，係利用純化自敏感品系家蠅腦部之乙醯膽鹼醋釀(acetyicholinesterase, AChE)，經ElIman’s test檢驗蔬果樣品中是否含有劇毒殺蟲劑之殘毒，目前可檢出前述兩大類具神經毒性藥劑（含個別藥劑達75 項以上），檢出感度可分兩段，為.l-0.8ppm及0.8-4ppm，分別具有不同之應用性。民國78 年創新完成以蘇力菌檢出殺菌劑殘毒之快速技術，除檢出有機硫磺劑外，亦適用於抗生素、銅劑等超過15 種之他類殺菌劑，檢出感度為1-2ppm 。以上兩項殺蟲劑及殺菌劑之檢驗技術經整合後，可在4 小時內完成50 件蔬果樣品之殘毒篩檢。 民國80 年結合酵素反應及薄層分析法完成殺蟲劑殘毒之定性定量分析，目前已建立個別藥劑在不同溶劑展開系統之Rf 值資料，可供查詢比對使用。83 年則再開發快速檢出organothiophosphates類藥劑之技術，係於樣品萃取時添加溴水，而將有機磷之P →S轉換為P →O，大幅提高檢出敏感度，目前僅有phosphoramidates藥劑尚因對AChE不敏感而無法快速檢出。 「蔬果農藥殘毒快速檢驗」技術經多年之推展，多處農會、合作社場、果菜市場及政府機關均已採用，目前全省已設置之檢驗工作站有60 餘處，農試所除提供檢驗試劑外，並定期辦理檢驗人員培訓及新技術之研習。快速檢驗之國際合作方面，除新加坡及泰國之農業部已於民國80 年及84 年分別派員至本所研習外，農試所並接受「亞太糧食肥料技術中心」之委託，針對亞太地區七個國家之學員，於82 年辦理國際「農藥殘毒快速檢驗技術」研習會，84 年起並至海外進行巡迴講習，84 年已於菲律賓辦理，85-87 年則將繼續於馬來西亞、越南及泰國辦理技術研習，訓練各國之工作人員。此項新技術因具高度之應用性，已在亞熱帶地區蔬果種類及病蟲害繁多之國家，成為與傳統之農藥殘毒化學分析方法平行互補之新興技術。 Chemical analysis for pesticide residues did not fit the diagnosing need in acute poisoning or monitoring the safety of fruit and vegetable in the fast-trading market. A toxicological method for the rapid screening and analyzing of pesticide residues has been developed by the combination of enzyme assay, microbial assay and TLC technique. Residues of organophosphorus and carbamate insecticides were detected by Eliman’s reaction with the acetylcholinesterase (AChE) and then determined by TLC for its identity, while the residue quantity was determined by the regression between pesticide concentration and % inhibition of AChE. Fungicide residue was assayed by Bacillus thuringiensis (B.t.) and then developed by TTC color reaction. One gram of plant sample was extracted with 1 ml methanol for insecticide test, or extracted with 2 ml of EDTA-DMSO solution for fungicide test. 20 ul of methanol extract was used for AChE assay, while 5-10 ul extract is enough for the qualitative TLC analysis. The thiophosphates were converted to their corresponding oxon-analogues by bromine water treatment in plant extract to increase the detectability by AChE. Houseflies head AChE is more sensitive than the AChE from electric eel or honeybee. The 25% inhibition was considered as the threshold for detecting the residues of organophosphorus compounds and carbamats. Currently, the Rf values in three solvent systems of more than 30 organophosphorus and carbamate insecticides have been established for TLC identification. The growth of B.t. is sensitive to the inhibition of ethylene bisdithiocarbamates (EBDC’s) and other fungicides such as chlorothalonil, dinocap, captan and folpet. The sensitivities of B.t. test to propineb, curzate-mancozeb, metalaxyl-mancozeb, mitram, mancozeb and maneb were above 0.7 ppm, and more than 12.5 ppm for zineb and Sankel. For chiorothalonil and dinocap, the sensitivity exceeded 2.5 ppm. By combining the spectrophotometric AChE reaction, microbial assay of B.t. and TLC/biochemical AChE color development, two neurotoxic insecticide groups and the ETU-producing fungicides can rapidly be detected qualitatively and quantitatively. This pesticide residue diagnosis system can be used for both medical and agricultural purposes. More than 60 RBPR stations have been established in Taiwan, and the RBPR has also been adopted as the vegetable safety screening method for Taipei Public Health Bureau. Started from 1995, RBPR has been officially adopted in a 5-year¡¦s training program of the FFTC (Food and Fertilizer Technology Center for the Asian and Pacific Region), and training workshops has been and will be held in other Asian countries i.e., Philippines (1995), Thailand (1995), Malaysia (1996), Vietnam (1997) and Korea (1997), respectively.