Simultaneous determination of procymidone, pyridaben and beta-cypermethrin residues in tea solution by GC-ECD.

A sensitive and effective method for the simultaneous quantitative determination of procymidone, pyridaben and beta-cypermethrin residues in tea solutions was developed and validated using a gas chromatograph (GC) equipped with an electron capture detector (ECD). The analysis of the three pesticides in tea solutions involved extraction with petroleum ether-ethyl acetate (3:1, v/v), cleanup using a Florisil solid-phase extraction cartridge and subsequent determination by GC-ECD. Recovery studies were carried out at three spiked levels (0.05, 0.1 and 0.5 mg/kg). The overall average recoveries using this method in green teas and black teas at the three concentration levels ranged from 85.63 to 105.80% with relative standard deviations in the range of 1.29-4.97% (n = 5) for all analytes. The quantification limits of procymidone, pyridaben and beta-cypermethrin were 0.025, 0.038 and 0.030 mg/kg, respectively, which were lower than the maximum residue limits (MRLs) of 0.1 mg/kg procymidone, 0.05 mg/kg pyridaben and 0.5 mg/kg beta-cypermethrin in tea samples established by European Union legislations. This study provides a theoretical basis for China to draw up MRLs for procymidone, pyridaben and beta-cypermethrin in tea solutions.