The overuse of plant growth promoters in agriculture, especially those derived from a synthetic cytokinin group, is increasing rapidly. In this study, the method for determining two plant growth hormones of the cytokinin group, including 6-benzylaminopurine and forchlorfenuron in bean sprouts, was developed based on the QuEChERS extraction technique in combination with LC-MS/MS detection and quantification. Chromatographic conditions include C18 reversed phase column, a gradient mobile phase system with two channels of H2O and MeOH, with the addition of 0.1% formic acid and 10 mM amonium formate. Triple quadrupole mass spectrometry detector, with positive electrospray ionization source (ESI+), multiple reaction monitoring (MRM) mode, was used to confirm the analytes’ presence. The sample preparation process was optimized using QuEChERS approach with acetonitrile as an extraction solvent, PSA as adsorbent. Method validation data includes the LOQ of 3.0 µg/kg, the recoveries from 79.1 - 117%, and the repeatability relative standard deviation from 3.0 - 7.0%, which meets the requirements of AOAC and European Union. The method was applied to analyze some bean sprouts samples in Hanoi city, 5 out of 6 samples were found to contain 6-benzylaminopurine with the content exceeding the EU’s maximum residue limit.
LC-MS/MS, QuEChERS, 6-benzylaminopurine, forchlorfenuron, bean sprout
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