Transfer rates on nine pesticides from dry tea to infusion by QuEChERS purification followed by LC-MS/MS analysis

Abstract

ABSTRACT In this study, the transfer rates of nine pesticides with different water solubility (imidaclothiz, acetamiprid, thiamethoxam, imidacloprid, clothianidin, carbendazim, pyraclostrobin, phoxim and etoxazole) from dry tea to infusion were carefully determined using the liquid-chromatography-tandem mass spectrometry (LC-MS/MS). The obtained results show that the transfer of each pesticide from tea spiked with the pesticides to the infusion ranged from 4.54% (etoxazole) to 58.0% (acetamiprid) under the traditional brewing condition in China, which indicates that transfer of pesticides was dependent on their water solubilities. Increases in infusion time resulted in increased transfer within 30 min. However, there was little influence of infusion time on transfer rates after 30 min. When the infusion temperature was between 50 and 100°C, the transfer rates of acetamiprid, thiamethoxam, imidacloprid, carbendazim, pyraclostrobin, phoxim and etoxazole increased with temperature, while transfer rates for imidaclothiz and clothianidin decreased with increasing temperature. After three infusions, the transfer rates of imidaclothiz, thiamethoxam, acetamiprid, and clothianidin were >70%. Our results provide a basis for the rational use of pesticides in tea gardens and a reasonable evaluation of dietary exposure levels of pesticide residues in brewed tea.