[Rapid screening of 125 pesticide residues in tea substitutes by multi-plug filtration cleanup method combined with gas chromatography-tandem mass spectrometry].

A rapid screening method for 125 pesticide residues of different polarities in tea substitutes matrix was developed using rapid screening combined with gas chromatography-tandem mass spectrometry （GC-MS/MS）. The targets were separated on DB-1701MS quartz capillary column （30 m×0.25 mm×0.25 μm） with programmed temperature rise， detected by GC-MS/MS in multiple reaction monitoring （MRM） mode， and quantified by matrix-matched solution internal standard method. The methodological validation of 125 representative pesticides in tea substitutes was carried out by GC-MS/MS method. The results showed that the tea samples could be extracted most efficiently when using acetonitrile without immersion in water. The M-PFC TD-1 column had a good purification effect on the Dendrobium officinale flower extract with a guaranteed high recovery. The results of optimized analysis showed that the 125 components had a good linear correlation in the range of 0.01 mg/L to 1.0 mg/L （R²>0.980）. The LODs and LOQs were 0.003-0.02 mg/kg （S/N=3） and 0.01-0.05 mg/kg （S/N=10），respectively. The recoveries of the 125 targets at three levels were in the range of 62.6%-107.6% with relative standard deviations （RSDs， n=6） of 1.0%-13.8%. Compared with other classical pretreatment methods， this method does not require activation， equilibration and elution steps， consumes less solvent， and the M-PFC TD-1 column shows better purification effect， which can directly adsorb large molecular interferences， such as pigments and alkaloids， in the matrix of the substitute tea， and is easy to operate， rapid， and with high sensitivity， which is suitable for the rapid screening of pesticide multicomponent residues in the bulk substitute tea. The method established in this study was used to monitor 50 samples of tea substitutes provided by the pilot production enterprises in Guizhou Province， in which at least one pesticide residue was detected in two samples of tea substitutes， with a detection rate of 4%. This study aims to enhance the scientific and practical aspects of setting local standard indicators or technical requirements by understanding the types and levels of pesticide residues in substitute tea products.