| China is the origin country as well as the hometown of tea. Tea is honored asnational drink in China. As one of the traditional primary export agriculture products,tea plays a significant role in international market. In recent years, major importcountries and regions such as EU and Japan have formulated stricter and stricterhygienic index, of which, the pesticide residue standards is the most distinct one,number of detecting items are increasing while MRL is reducing.Since impurity contents of organic acid, pigment and phenols extracted fromvarious tea and areas are different, the author collected311tea samples from Fujian,Zhejiang, Anhui, Yunnan and Sichuan Provinces, extracted by petroleum ether andclassified extracting solutions from light to dark, then researched on organochlorineand pyrethroids, thus formed the test methods for9organic chlorides and12pyrethroids.For different tea varieties in sulfonated method, the required concentratedsulphuric acid amounts are different. Tested by GC-uECD, the correlation coefficientof linear equation of (the following)9organochlorines are between0.987-0.998(α-HCH、β-HCH、γ-HCH、δ-HCH、p,p’-DDE、o,p’-DDD、o,p’-DDT、p,p’-DDT、DicofoL), the recovery percentages are between87.35%-111.20%, which can totallymeet up with the9organochlorines pesticide residue detection requirements.By graphitized Carbon, N-propyl ethylenediamine and Anhydrous sodiumsulfate, the Solid-Phase Extraction decontaminating column are filled for differenttea. Detected by GC-uECD, the correlation coefficient of linear equation of thefollowing12pyrethroids are between0.986-0.997: Bifenthrin, Fenpropathrin,Permethrin （I II）, Cypermethrin （I II III）, Flucythrinate （I II）, Fenvalerate （III）, Deltamethrin, and the recovery percentages are between71.72%-124.25%,which can basically meet up with the pesticide residue detection recoveryrequirements.Tests on the311samples also show that the dicofol in Tie Guan Yin tea andfenvalerate in green tea are comparatively over standards. |
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