Determination of pesticide and phthalate residues in tea by QuEChERS method and their fate in processing.

Abstract

In this study, the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method was applied for the analysis of the multiclass pesticide residues of 12 organochlorines (OCs), 9 organophosphates (OPs), 11 synthetic pyrethroids (SPs), 4 herbicides, 6 phthalates in raw tea (loose tea, branded tea and herbal tea), and tea infusion in 4 different containers (glass cup, earthen cup, plastic bag and disposal cup). In loose tea and branded tea residues, malathion (0.257 and 0.118mgkg-1), cypermethrin (0.065 and 0.030mgkg-1), and fenvalerate (0.032 and 0.030mgkg-1) were detected, respectively. In herbal tea, residues of only cypermethrin (0.053mgkg-1) and fenvalerate (0.045mgkg-1) were detected. Tea infusion samples contained in a plastic bag were found to be contaminated with only dibutyl phthalate (DBP) (0.038mgkg-1). Disposable cup was found to be contaminated with DBP (0.026mgkg-1) and diethyl phthalate (DEP) (0.004mgkg-1). Further, to know the processing behavior of pesticides, the spiked raw tea was subjected to tea infusion at different brewing times (2, 5, 10min). The analysis demonstrated that dimethoate, dichlorvos, and malathion had shown more than 10% of translocation at 5min of brewing time. Further brewing for 10min revealed the reduction in concentration of pesticides. Leaching of phthalate residues from different plastic containers was also studied at 10, 30, and 60min. DBP, benzyl butyl phthalate (BzBP), and di-2-(ethylhexyl) phthalate (DEHP) were leached in the tea infusion samples packed in plastic bags. On the other hand, in disposable cups, leaching of DBP, DEP, and dimethyl phthalate were found. The concentration of phthalate residues increased with retention time. Pesticide and phthalate contaminants were recorded at low quantities in few samples only.