陈香型铁观音原料农药残留分析及其降解方法初探

Analysis on Pesticide Residues Level in Dry Tea Materials of Chenxiang Tieguanyin and the Preliminary Studies on the Degradation of Pesticide Residues

近年来,陈香型铁观音的消费群体不断扩大。为了解陈香型铁观音的质量安全情况,从福建省采集陈香型铁观音干茶原料89份,采用超高液相色谱-质谱联用仪(UPLC-MS)、气相色谱-质谱联用仪(GC-MS)等手段,对样品的47种农药残留量进行检测。结果显示,检出率较高的农药为三氯杀螨醇(87.64%的样品检出)和氰戊菊酯(30.34%的样品检出),其中,37.08%的样品三氯杀螨醇含量超过中国最高残留限量(MRL),25.84%的样品氰戊菊酯含量超过中国或欧盟MRL值。另外,11.24%的样品检出滴滴涕残留,其中2个样品的滴滴涕残留量超出欧盟值和中国MRL值。氯氰菊酯、联苯菊酯、氯氟氰菊酯、硫丹、草甘膦等在陈香型铁观音的部分原料中也有检出,均未超过欧盟和中国MRL值。六六六、辛硫磷、杀螟丹等27种农药未检出。利用烘箱热解、紫外光解和微波热解法对样品三氯杀螨醇和氰戊菊酯残留量的降解效果进行比较,得出紫外降解法效果最佳,是一种值得进一步研究的干茶农残降解的可行方案。本研究认为,陈香型铁观音原料虽然存在三氯杀螨醇和氰戊菊酯超标情况,但二者均属于酯溶性农药,其在茶汤中的溶出率和人体实际吸收量有待探讨。另外,后期的拼配和焙火工艺可能使陈香型铁观音成品茶的农残情况得到改善。

In recent years,the consumption of Chenxiang Tieguanyin has been expanding.In order to understand the quality and safety of Chenxiang Tieguanyin,89 dried tea materials of Chenxiang Tieguanyin,which are not experienced mixing,were collected from Fujian province.47 pesticide residues in the samples were detected by ultra-high performance liquid chromatography-mass spectrometry(UPLC-MS),gas chromatography-mass spectrometry(GC-MS),etc.The results showed that the pesticides with high detection rate were dicofol(87.64%of the samples contained the pesticide)and fenvalerate(30.34%of the samples contained the pesticide),the dicofol contents in 37.08%samples exceeded the maximum residue limit(MRL)of China,and the fenvalerate contents in 25.84%exceeded the MRL of China or EU.In addition,11.24%samples have DDT residues,the contents in two of them exceeded the EU and China MRL.The detection rates of cypermethrin,bifenthrin,cyhalothrin,endosulfan and glyphosate on Chenxiang Tieguanyin were also high,but they did not exceed the MRL of EU and China.27 pesticides,includes hexachlorocyclohexane,phoxim,fenitrothion,etc.were not detected in all samples.Finally,the degradation effects of dicofol and fenvalerate residues in samples were compared by baking oven treatment,ultraviolet rays treatment and microwave oven treatment.The result showed that the ultraviolet degradation method has the best effect and is a feasible method for the degradation of pesticide residues in dried tea,which is worthy of further study.In this study,although the contents of dicofol and fenvalerate in some of the dry tea materials of Chenxiang Tieguanyin exceed the standard content levels,they are ester-soluble pesticides,and their dissolution rate in tea soup and actual absorption in human body need to be studied.In addition,the late mixing and roasting process may improve the pesticide residues situation of Chenxiang Tieguanyin products.