Determination of Ochratoxin A in Beer by Immunoaffinity Cleanup and Liquid Chromatography with Tandem Mass Spectrometry

摘要

A simple and sensitive method for the analysis of ochratoxin A in commercial beer products was developed using an immunoaffinity column for clean up and liquid chromatography with tandem mass spectrometry (LC/ MS/MS). Beer was degassed, diluted with a polyethylene glycol/sodium hydrogen carbonate solution, and applied to an immunoaffinity column. Ochratoxin A was eluted from the immunoaffinity column with methanol/acetic acid (98:2, vol/vol) and quantified by LC/MS/MS. The LC separation was performed with an octadecylated silica column (particles were 3.5 μm and 100 mm long and had a 2.1 mm i.d.), with a flow rate of 0.2 mL/min and a mobile phase consisting of water and acetonitrile, including 0.1 % formic acid. MS/MS was used in multiple-reaction monitoring employing elec-trospray ionization (ESI-MRM). The recovery of ochratoxin A was 90.8-94.2% from beer spiked at 0.02 ng/mL. When the method was applied to the analysis of 33 domestic beer products, the ochratoxin A content ranged from 0.0026 to 0.049 ng/mL.