Determination of 17 Plant Growth Regulator Residues by Ultra-High Performance Liquid Chromatography-Triple Quadrupole Linear Ion Trap Mass Spectrometry Based on Modified QuEChERS Method

A new method combining modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) with ultra-high performance liquid chromatography-triple quadrupole linear ion trap mass spectrometry (UHPLC-QTrap-MS/MS) was developed for simultaneous determination of 17 plant growth regulator (PGR) residues in vegetables. Quantitative data acquisition was accomplished in multiple reaction monitoring (MRM) mode, and qualitative analysis and identification of target compounds was achieved by using linear ion trap scan functions. Qualitative and quantitative analysis can be simultaneously achieved by a pair of ions in UHPLC-QTrap-MS/MS. More importantly, QTrap system can minimize the risk of false positive and negative results. To achieve the optimum performance towards the target analytes, several parameters including the content of formic acid in mobile phase and scanning mode were investigated. In the optimized conditions, 17 PGRs showed good linearity over the range of 2 similar to 50 mu g/L with correlation coefficients of 0.9902 similar to 0.9999. The limits of detections (LODs) were in the range of 0.01 similar to 1.32 mu g/kg. The recoveries of 17 PGRs ranged from 78.5 to 119.2% with the spiked levels of 1, 2, and 5 mu g/kg into homogenized radish, and the relative standard deviations (RSDs) ranged from 0.8 to 14.8%. The method illustrated is suitable for routine quantitative and qualitative analyses of PGRs in vegetable samples.