Determination of 6-benzyladenine in bean sprout by LC-ESHT-MS-MS

A rapid and sensitive method has been developed and validated to determine 6-benzyladenine (6-BA) residues in bean sprout using high-performance liquid chromatography coupled with electrospray ionization ion trap tandem mass spectrometry. Liquid-liquid extraction, using acidified methanol, was used to isolate 6-BA from the sample matrix. The separation was carried out on a Zorbax SB C-18 column (150 mm x 4.6 mm i.d., 5 mu m) with 0.1% acetic acid/methanol (25:75 v/v) as mobile phase in isocratic mode. The quantitation of 6-BA was based on fragmentation of the molecular ion at m/z 226.1 to a product ion at m/z 91.1. In addition, the recoveries of three extraction solvents by ultrasound extraction and conventional extraction method were compared, and it was found that acidified methanol as the extraction solvent was the best. The calibration curve was linear (r(2) > 0.997) in the concentration range of 0.04-10.0 ng mL(-1) with a lower limit of quantification of 0.5 ng g(-1) for 6-BA in bean sprout. Intra-day and inter-day relative standard deviations (RSDs) were less than 7.1 and 9.8%. Recoveries of 6-BA were between 85.0 and 88.5%. This assay has been successfully applied to the determination of trace 6-BA residues in bean sprout and monitoring the market in Ningbo, China.