Determination and survey of ochratoxin A in wheat, barley, and coffee - 1997

Ochratoxin A (OA) is a nephrotoxic and nephrocarcinogenic mycotoxin produce d by Aspergillus and Penicillium species. it has been found mainly in cerea l grains and coffee beans. The purpose of this study was to investigate the occurrence of OA in cereal grains and in coffee imported to the United Sta tes. A modified liquid chromatographic (LC) method for determining OA in gr een coffee was applied to wheat, barley, green coffee, and roasted coffee. The test sample was extracted with methanol-1% NaHCO3 (7 + 3), and the extr act was filtered. The filtrate was diluted with phosphate-buffered saline ( PBS), filtered, and passed through an immunoaffinity column. After the colu mn was washed with PBS and then with water, OA was eluted with methanol, Th e eluate was evaporated to dryness, and the residue was dissolved in aceton itrile-water (1 + 1). OA was separated on a reversed-phase Cls LC column wi th acetonitrile-water-acetic acid (55 + 45 + 1) as eluant and quantitated w ith a fluorescence detector. Recoveries of OA from the 4 commodities spiked over the range 1-4 ng/g were 71-96%, The limit of detection was about 0.03 ng/g, OA contamination at >0.03 ng/g was found in 56 of 383 wheat samples, 11 of 103 barley samples, 9 of 19 green coffee samples, and 9 of 13 roaste d coffee samples. None of the coffee samples contained OA at >5 ng/g; only 4 samples of wheat and 1 sample of barley were contaminated above this leve l.