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
[1]. A. Basra, Plant growth regulators in agriculture and horticulture: their role and commercial uses, CRC Press, 2000.
[2]. E. F. George, M. A. Hall, G. J. D. Klerk, “Plant growth regulators II: cytokinins, their analogues and antagonists”, Plant propagation by tissue culture, Springer, pp. 205-226, 2008.
[3]. Bộ Nông nghiệp và Phát triển Nông thôn, Thông tư ban hành Danh mục thuốc bảo vệ thực vật được phép sử dụng, cấm sử dụng tại Việt Nam, Hà Nội, 2019.
[4]. W. Zhang, L. He, R. Zhang et al., “Development of a monoclonal antibody-based enzymelinked immunosorbent assay for the analysis of 6-benzylaminopurine and its ribose adduct in bean sprouts”, Food Chemistry, vol. 207, pp. 233-238, 2016.
[5]. F. Wang, W. Zhang, Y. Chen et al., “Simultaneous determination of six plant growth regulators in fruits using high performance liquid chromatography based on solid-phase extraction and cleanup with a novel mixed-mode functionalized calixarene sorbent”, Analytical Methods, vol. 7, no. 15, pp. 6365-6371, 2015.
[6]. S. Liu, Y. Wu, C. Fang, Y. Cui, N. Jiang & H. Wang, “Simultaneous Determination of 19 Plant Growth Regulator Residues in Plant-originated Foods by QuEChERS and Stable Isotope Dilution - Ultra Performance Liquid Chromatography-Mass Spectrometry”, Analytical Sciences, vol. 33, no. 9, pp. 1047-1052, 2017.
[7]. L. Ma, H. Zhang, W. Xu et al., “Simultaneous determination of 15 plant growth regulators in bean sprout and tomato with liquid chromatography-triple quadrupole tandem mass spectrometry”, Food Analytical Methods, vol. 6, no. 3, pp. 941-951, 2013.
[8]. AOAC Official Methods of Analysis, Appendix F: Guidelines for standard method performance requirements. 2012.
[9]. European Commission, Method Validation and Quality Control Procedures for Pesticide Residues Analysis in Food and Feed, SANTE/12682/2019, 2019.
[10]. European Commission, Maximum residue levels of pesticides in or on food and feed of plant and animal origin and amending Council Directive 91/414/EEC, EC 396/2005, 2005.