Liu Kang-shu, Wang Xing-ning, Cai Qiu

(Guizhou Entry Exit Inspection and Quarantine Bureau of Peoples Republic of China, Guizhou 550004, China) 

Abstract A solid phase extraction(SPE)-gas chromatography(GC)-negative chemical ionization mass spectrometry(NCI/MS) method has been set up for the analysis of 3 acaricides and octachloro-dipropyl-ether pesticides in tea, and has been applied to the detection and base regulation of pesticide residues in tea for EU exports. Pesticide residues were extracted from tea samples with hexane-acetone(1∶1,by vol) and cleaned-up by active carbon and Florisil SPE column to remove co-extractives, and with heptachlor-epoxide as the internal standard. Analytical screening was determined by the technique of gas chromatography-negative chemical ionization mass spectrometry-selected ion monitoring. The recoveries of all pesticides were in the range of 80％～110％at three spiked level(5～80 μg/kg) and relative standard deviations were below 5.5%.The detection limits of tetradifon, dicofol, pyridaben, and S-421 are 0.1 μg/kg, 0.4 μg/kg, 1.0 μg/kg and 2.0 μg/kg respectively.The method showed excellent sensitivity and selectivity for 3 acaricides and octachloro-dipropyl-ether pesticides.

Key words: negative chemical ionization(NCI) ,selected ion monitoring, solid phase extraction, Acaricide and Octachloro-Dipropyl-Ether pesticides, tea

E-mail: liukangshu0416@sina.com

Analysis and Testing Technology and Instruments, Vol. 17, No. 2, 2011, 101-105.