Simultaneous Determination of Plant Growth Regulators and Imidacloprid, Acetamiprid in Tea by Ultra Performance Liquid Chromatography-Tandem Mass Spectrometry

An efficient method for the analysis of multiclass plant growth regulators and pesticide (imidacloprid, acetamiprid) residues in tea was developed based on ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The samples were extracted with acetonitrile/formic acid (99: 1, V/V) solution, cleaned up with four sorbents including C-18, strong anion exchanger (SAX), primary secondary amine (PSA) and anhydrous MgSO4. The compounds were separated on a HSS T3 column under positive/negative electrospray ionization mode, detected by scheduled multiple reaction monitoring (SMRM), and quantified by matrix-matched external standard curves. All pesticide residues showed good linearity in the concentration range of 1 - 200 mu g/L (6-benzylaminopurine, paclobutrazol, uniconazole, forchlorfenuron, mepiquat chloride, imidacloprid, acetamiprid) or 5 - 1000 mu g/L (2,4-dichlor-ophenoxyacetic acid, 4-chlorophenoxyacetic acid, indole-3-acetic acid, gibberellic acid, 1-naphthaleneacetic acid, indole-3-butyric acid), with correlation coefficient (R-2 >= 0. 99). Limits of detection (LOD, S/N = 3) and limits of quantitation (LOQ, S/N = 10) were 0. 18-9. 68 mu g/kg and 0. 61-32. 26 mu g/kg, respectively. In addition, the spiked recoveries of tea samples were 73. 1% - 108. 9%, and RSDs were 0. 6% - 8. 0%. This method was applied to commercial samples, and all the detections were confirmed by acquiring transitions for each pesticide in the samples.