A reliable isotope dilution method for simultaneous determination of fumonisins B1, B2 and B3 in traditional Chinese medicines by ultra-high-performance liquid chromatography-tandem mass spectrometry

A reliable isotope dilution method for simultaneous determination of fumonisin B1, fumonisin B2 and fumonisin B3 in traditional Chinese medicines by ultra-high-performance LC-MS/MS was developed, and a special focus was placed on the optimization of extraction, cleanup, ultra-high-performance LC separation and MS/MS conditions. Homogenized samples were extracted by 50% acetonitrile aqueous solution and purified with MultiSep 211 Fum columns. A linear gradient mobile phase, consisting of water containing 0.2% formic acid and acetonitrile/methanol (50:50 v/v) and an Acquity UPLC HSS T3 column (100 mm x 2.1 mm, 1.8 mu m) were employed to obtain the best resolution of the analytes for the positive ESI+ analysis. The established method was validated by determining the linearity (R-2 >= 0.9991), sensitivity (LOQ, 0.08-0.16 ng/mL), recovery (88.2-113.3%) and precision (RSD <= 12.3%). Finally, the validated method was successfully applied to the determination of fumonisins in different traditional Chinese medicines. Of 35 samples, 18 were contaminated with fumonisins. The mean levels (incidence) of fumonisin B1, fumonisin B1 and fumonisin B1 in positive samples were 8.55 (94.4%), 4.88 (77.8%) and 0.52 mu g/kg (33.3%), respectively. Based on the contaminant situations, a possible association between the contamination levels and the selected herbs was clarified in this study.