[HPLC analysis of alfatoxins in medicinal herb extracts by immunoaffinity column cleanup and post-column bromination]

To develop a new and accurate method to quantify aflatoxins in medicinal herbs.

This method consists of sample extraction by using MeOH-H2O (7:3), followed by clean-up with an immunoaffinity column, and finally HPLC determination with fluorescence detection. Aflatoxins B1 and G1 are determined as their bromine derivatives, produced in an on-line post-column derivatization system.

The overall average recoveries for different medicinal herbs spiked at two levels of standards were from 90.4% to 99.7%. The detection limit was 0.06 microg x kg(-1) for aflatoxins G2 and B2, and 0.20 microg x kg(-1) for aflatoxins G1 and B1.

The use of immunoaffinity column provides excellent cleanup of interfering substances. The method has been applied successfully to analyze 96 natural drugs.