High Pressure Liquid Chromatographic Determination of an O-Methyl, Methyl Ester Derivative of Ochratoxin A

The mycotoxin ochratoxin A (OA) was derivatized to an O-methyl,methyl ester (Me2) with diazomethane and then determined by high pressure liquid chromatography (HPLC). Both OA and OA-Me2 were chromatography by reverse phase HPLC with a mobile phase of acetonitrile-water (60 + 40). An increase in retention time of 309 s was observed with OA-Me2 which was detectable at 254 nm at levels as low as 3 ng. Recovery of OA as OA-Me2 from chicken kidney homogenates and human plasma was quantitative following simple extraction and cleanup procedures, reaction with diazomethane, and HPLC analysis. The novel method described should prove useful for measuring and confirming OA in tissues and in further studies on the biological fate of this mycotoxin.