Colorimetric detection of 6-benzylaminopurine residues in vegetables based on Fe3O4 magnetic molecular-imprinted nanoparticles

[Objective] Achieving a rapid, sensitive, and visual detection of 6-benzylaminopurine （6-BA） residues in vegetables. [Methods] Based on the peroxidase-like activity and specific recognition of Fe3O4 magnetic molecularly imprinted nanoparticles （Fe3O4 MMIP NPs）, a simple, rapid and highly selective colorimetric method was established to detect 6-BA residues in vegetables. [Results] Fe3O4 MMIP NPs exhibits optimal peroxidase-like catalytic activity at pH 4.0, 0.02 mol/L TMB, 0.02 mol/L H2O2 and a reaction time of 5 min. 6-BA showed a good linear relationship with the difference between the blank and the sample absorbance value in the mass concentration range of 1~300 ng/mL with a limit of detection at 0.697 ng/mL. The method was successfully applied to the detection of 6-BA residues in vegetables （cucumber, tomato, bean sprouts, mung bean sprouts）. The recovery rate was 83.47%~106.76%, with a relative standard deviation of 0.37%~5.66%. In addition, Fe3O4 MMIP NPs could still maintain good catalytic activity after 60 days of storage at 4 ℃. [Conclusion] The colorimetric method for the detection of 6-BA based on Fe3O4 MMIP NPs has the advantages of simplicity, rapidity, economy, and can be used for the detection of 6-BA residues in vegetables, which has certain reliability and practicability.