Simultaneous Determination of 19 Plant Growth Regulator Residues in Plant-originated Foods by QuEChERS and Stable Isotope Dilution-Ultra Performance Liquid Chromatography-Mass Spectrometry

In this study, a highly sensitive and fast method of QuEChERS (acronym of quick, easy, cheap, effective, rugged, safe) combined with isotope dilution-ultra performance liquid chromatography coupled to tandem mass spectrometry was developed for the simultaneous determination of 19 plant growth regulators in plant-originated foods. The samples were initially extracted with acetonitrile containing 1% acetic acid and then the QuEChERS method was applied after the pH value was adjusted to 5.5 - 6.0, using 3-indolepropionic-d(2) acid and forchlorfenuron-d(5) as internal standard. The targeted 19 plant growth regulators were separated on an HSS T-3 column using acetonitrile: 5 mmol/L ammonium acetate as the mobile phase. Quantitative results were based on multiple reaction monitoring mode after ionization in positive and negative electrospray ionization mode. Good linearity was achieved within a wide range and all the correlation coefficients were greater than 0.997. The limit of quantification was 0.060 - 6.0 mu g/kg. Rate of recovery and relative standard deviation were 72.3 - 115.8 and 1.78 - 5.32%, respectively. The method was successfully applied to measure 19 plant growth regulator residues in 280 plant-originated commercial foods collected from local supermarkets in China. Twelve plant growth regulators were found in some of the analyzed samples.