Abstract: A method was established for the determination of two plant growth regulators, forchlorfenuron (CPPU)and gibberellin acid (GA3), in the grapes using high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The sample was extracted with 0.5%(v/v) formic acid aqueous solution and acetonitrile (4:1, v/v), and cleaned-up with Strata-X solid phase extraction cartridge. The separations were performed on an Agilent SB-C18 column (50 mm×2.1 mm, 1.8 μm), with a mobile phase of 0.5% formic acid aqueous solution-acetonitrile at a flow rate of 0.3 mL/min and detected by electrospray ionization MS/MS under the multiple reaction monitoring (MRM) mode. The results showed that the good linear relationships and the correlation coefficients greater than 0.999 were obtained. The limits of detection (LODs) were 0.5 μg/L and 0.3 μg/L for CPPU and GA3, respectively. The limits of quantification (LOQs) were 2.0 μg/L and 1.0 μg/L for CPPU and GA3, respectively. The recoveries were 91.7%~95.6% and 90.3%~94.2% with the relative standard deviations (RSD) of 4.1%~7.3% and 3.2%~6.9% for CPPU and GA3, respectively. The results indicate that the method is accurate and can be used for the determination of CPPU and GA3 residues in the grapes.

Key words: forchlorfenuron (CPPU), gibberellin acid (GA3), grape, high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS)