Analysis of 46 pesticides in teas of Fuzhou City, Fujian Province, China.

A modified QuEChERS method coupled with LC-MS/MS was established to detect and quantify 46 pesticide residues in tea. The samples were extracted and subsequently purified using dispersive solid phase extraction sorbents such as primary secondary amine (PSA), graphitised carbon black (GCB), and octadecylsilane (C18). Matrix-matched calibration curves with regression coefficients R2 ≥ 0.99 were used to minimise the matrix effect. The recoveries of different spiked levels ranged from 65.6% to 120%, with relative standard deviations (RSDs) between 1.7% and 8.9%. The limits of detection (LOD) and of quantification (LOQ) ranged from 0.01-8.8 μg/kg and 0.02-29.2 μg/kg, respectively. A number of 305 tea samples of farmers' markets in Fuzhou City, Fujian Province, China, were analysed for 46 pesticide residues, of which 16 were detected in 211 samples.