LIQUID-CHROMATOGRAPHIC METHOD FOR ANALYSIS OF THE NAPHTHALENE DICARBOXALDEHYDE DERIVATIVE OF FUMONISINS

A liquid chromatographic (LC) method for determining fumonisins in cor n, feed, and laboratory cultures was optimized. We investigated the ef ficiency of extraction solvents, the performance of cleanup columns, t he stability of fluorescent derivatives, and the efficiency of LC colu mns to separate derivatized fumonisins from interferences so that we c ould develop a sensitive, reliable assay for fumonisins. Maximum extra ction efficiency was accomplished by shaking contaminated samples in a cetonitrile-water (50 + 50, v/v) for 1 h; methanol-water mixtures and other ratios of acetonitrile-water were less efficient. Solid-phase ex traction cleanups on reversed-phase C-18 and strong anion exchange (SA X) columns were compared. The SAX columns were very efficient in isola ting fumonisins from crude extracts; however, only the C-18 columns co uld be used to partially purify fumonisin hydrolysis products. A highl y fluorescent and stable derivative, prepared from naphthalene-2,3-dic arboxaldehyde, proved to be suitable for LC analysis. Both parent comp ounds and hydrolysis products were separated in a simple gradient syst em of acetonitrile-acetic acid and water-acetic acid in less than 30 m in.