A Rapid Fluorometric Test for Aflatoxins in Grains and Raw Peanuts

Abstract

A rapid method for the fluorometric analysis of aflatoxins in corn, corn meal, popcorn, rice, wheat, cottonseed and peanuts was developed. This method proved to be quantitative, inexpensive and very efficient. Ground samples of the commodity being tested are extracted with methanol-water (80+20) and cleaned up by passage through a solid-phase separatory column. Five hundred μl of purified extract is derivatized with a bromine reagent and the fluorescence of the solution is quantified with a calibrated fluorometer. This method will quantify aflatoxin from 5 to 5000 ppb without dilution and was linear when applied to samples of noncontaminated corn spiked at 0 to 5000 ng aflatoxin B1/g. Correlation coefficients of the method with HPLC for multiple analyses for corn (n=34), cottonseed (n=32) and peanuts (n=11) were 0.999, 0.995 and 0.980, respectively. Individual analyses can be conducted in less than 5 min and grouping of samples is unnecessary. The sensitivity of the method for corn is 5 ppb and the fluorometer, operating under the prescribed conditions, has a limit of detection of 0.6 ng of aflatoxin B1.