High Pressure Liquid Chromatographic Determination of Ochratoxin A and Zearalenone in Cereals

Abstract

A high pressure liquid chromatographic (HPLC) method has been developed for determining ochratoxin A and zearalenone in cereals. The sample is extracted with phosphoric acid and chloroform. The extract is cleaned by washing on a silica gel column with cyclohexane-ethylene dichlorideethyl ether. After eluting zearalenone with chloroform, ochratoxin A is eluted with chloroformformic acid. Zearalenone is extracted into alkaline solution, washed with chloroform, the pH is adjusted, and the zearalenone is extracted back into chloroform. Ochratoxin A is purified by chromatography on aqueous sodium bicarbonate-Celite. The mycotoxins are determined by using a liquid chromatograph with 2 columns in series packed with Spherisorb ODS 10 μm and 5 μm, respectively. Ochratoxin A is detected with a spectrophotofluorometer, coupled in series with an ultraviolet detector for estimation of zearalenone. Detection limits are 1-5 μg/kg for ochratoxin A and 2 μg/kg for zearalenone.