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-d2 acid and forchlorfenuron-d5 as internal standard. The targeted 19 plant growth regulators were separated on an HSS T3 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 μg/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.