UPLC-MS/MS Determination of Residual Amounts of 34 Plant Growth Regulators in Fruits and Vegetables with Solid Phase Extraction

A method was proposed for the simultaneous determination of residual amounts of 34 plant growth regulators in fruits and vegetables by UPLC-MS/MS with solid phase extraction. The sample of 2.000 0 g was extracted with 10.0 mL of acetonitrile and purified by passing through Oasis PRiME HLB solid phase extraction column. The eluate of 5.0 mL was taken and concentrated to dryness by N₂-blowing, and the residue was dissolved and made its volume up to 1.0 mL with methanol (1+9) solution. The Waters CSH fluorophenyl chromatographic column was used as stationary phase, and the mixture of methanol and 5 mmol·L^-1 ammonium acetate solution containing 0.1% (φ) acetic acid was used as mobile phase for gradient elution. ESI⁺, ESI^- and the mode of multi-reaction monitoring were adopted in MS/MS, and external standard method was used for quantification. Linear relationships of 34 plant growth regulators were found in definite ranges, with detection limits (3S/N) in the range of 0.01-0.20 μg·kg^-1. Test for recovery was made by standard addition method, giving results in the range of 71.0%-115%, with RSDs (n=6) ranged from 0.60% to 16%.