Simultaneous Determination of Plant Growth Regulators in Fruit by Ultra-performance Liquid Chromatography-Tandem Mass Spectrometry Coupled with Modified QuEChERS Procedure

Abstract Five plant growth regulators, uniconazole, 6-benzyladenine, kinetin, 4-chlorophenoxyacetic acid and diethyl aminoethyl hexanoate, frequently used in apple, grape, strawberry, peach and orange, were determined by ultra-performance liquid chromatography–tandem mass spectrometry (UPLC-MS/MS). A modified QuEChERS (Quick, easy, cheap, effective, rugged and safe) procedure was used in sample pretreatment, which involved extraction with acetonitrile containing 1% acetic acid and clean-up with a mixture of ODS and MgSO 4 . Mass spectrometric determination was performed in multiple reaction monitoring mode (MRM) using external standards for calibration. The results indicated that the calibration curves for the target analytes were linear in the range of 1–100 μg L −1 with correlation coefficients greater than 0.999. The recoveries at three spiked levels ranged from 71.82% to 109.24% with RSDs from 0.57% to 12.43%. The respective limits of detection (LOD) and limits of quantification (LOQ) were 0.15–0.45 μg kg −1 and 0.51–1.50 μg kg −1 for uniconazole, 0.28–0.53 μg kg −1 and 0.94–1.75 μg kg −1 for 6-benzyladenine (6-BA), 0.15–69 μg kg −1 and 0.51–2.29 μg kg −1 for kinetin (6-KT), 0.22–0.60 mu;g kg −1 and 0.74–2.01 μg kg −1 for 4-chlorophenoxyacetic acid (4-CPA), 0.88–1.89 μg kg −1 and 2.89–6.29 μg kg −1 for diethyl aminoethyl hexanoate (DA-6).