Aqueous extraction followed by dispersive solid phase extraction with in situ derivatization for the determination of aflatoxins in traditional Chinese medicines

A green sample preparation method based on aqueous extraction followed by dispersive solid phase extraction (d-SPE) with in situ derivatization (ISD) was developed for the determination of aflatoxins (AFs) in traditional Chinese medicines (TCMs). AFs in TCMs were extracted by alkaline aqueous solution and converted to substituted coumaric acids. Then, mixed-mode anion exchange (MAX) sorbent was used to isolate and enrich the substituted coumaric acids. During the elution by acetonitrile/trifluoroacetic acid solution, AFs were reconstructed and in situ derivatized. Several parameters affecting the procedure were evaluated. The developed preparation method coupled with high performance liquid chromatography-fluorescence detection was successfully applied for AFs determination in TCMs. The limit of detection (LOD) reached 10 pg/mL for AFs. Good linearity was obtained in three orders of magnitude with correlation coefficients ranging from 0.9996 to 0.9999. The relative recoveries of the method were between 72.7% and 114.5% with intra- and inter-day relative standard deviations (RSDs) less than 9.5% and 10.1%, respectively. The method was successfully applied to determine AFs in 15 kinds of TCMs in China, with the results verified by IAC standard method.