Liquid Chromatographic Method for Analysis of the Naphthalene Dicarboxaldehyde Derivative of Fumonisins

Abstract

A liquid chromatographic (LC) method for determining fumonisins in corn, feed, and laboratory cultures was optimized. We investigated the efficiency of extraction solvents, the performance of cleanup columns, the stability of fluorescent derivatives, and the efficiency of LC columns to separate deri-vatized fumonisins from interferences so that we could develop a sensitive, reliable assay for fumonisins. Maximum extraction efficiency was accomplished by shaking contaminated samples in acetonitrile–water (50 + 50, v/v) for 1 h; methanol–water mixtures and other ratios of acetonitrile–water were less efficient. Solid-phase extraction cleanups on reversed-phase Cia and strong anion exchange (SAX) columns were compared. The SAX columns were very efficient in isolating fumonisins from crude extracts; however, only the C18 columns could be used to partially purify fumonisin hydrolysis products. A highly fluorescent and stable derivative, prepared from naphthalene-2,3-dicar-boxaldehyde, proved to be suitable for LC analysis. Both parent compounds and hydrolysis products were separated in a simple gradient systjem of acetonitrile-acetic acid and water-acetic acid in less than 30 min.