Abstract: An analytical method was developed to determine three fumonisins in corn and wheat flour samples using on-line solid phase extraction combined with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS-MS). Samples were extracted with an acetonitrile-water mixture (50:50, V/V) and purified with an on-line solid phase extraction column (WAX column). The fumonisins were separated on an XBridge C18 colum by using 0.1% formic acid solution mixed with acetonitrile as the mobile phase. Multiple reaction monitoring was used to acquire mass spectrometric data under positive electrospray ionization mode. The internal standard method was adopted for quantification. The results showed that good linearity was obtained in the range of 0.05–50 ng/mL for fumonisin B1, fumonisin B2 and fumonisin B3, and the correlation coefficients were all greater than 0.999 0. The limits of detection (LOD) and quantitation (LOQ) for these analytes were 0.08 and 0.2 μg/kg, respectively. Recoveries of the method were in the range of 93.9%–117.8% at spiked levels between 0.2 and 50 μg/kg, and precision (expressed as relative standard deviation) ranged from 1.8% to 9.4%. The developed method could be used for the accurate quantitative measurement of fumonisins in corn and wheat flour samples.

Key words: on-line solid phase extraction, liquid chromatography-tandem mass spectrometry, isotope dilution, fumonisin