Determination of ochratoxin A in wine by means of immunoaffinity column clean-up and high-performance liquid chromatography

A new and accurate method to quantify ochratoxin A (OA) in table wine has b een developed. The method uses commercial immunoaffinity columns for clean- up and high-performance liquid chromatography (HPLC) with fluorescence dete ction for quantification of the toxin. Wine was diluted with a solution con taining 1% polyethylene glycol (PEG 8000) and 5% sodium hydrogencarbonate, filtered and applied to an OchraTest immunoaffinity column. The column was washed with a solution containing sodium chloride (2.5%) and sodium hydroge ncarbonate (0.5%) followed by water. OA was eluted with methanol and quanti fied by reversed-phase HPLC with fluorometric detection (excitation wavelen gth 333 nm, emission wavelength 460 nm) using acetonitrile-water-acetic aci d (99:99:2) as mobile phase. Average recoveries of OA from white, rose and red wine samples spiked at levels from 0.04 to 10 ng/ml ranged from 88% to 103%, with relative standard deviations (RSDs) between 0.2 and 9.7%. Detect ion limit was 0.01 ng/ml based on a signal-to-noise ratio of 3:1. The metho d was applied successfully to 56 samples of red (38), rose (8), white (9) a nd dessert (1) wine. The levels of OA ranged from <0.01 to 7.6 ng/ml with r ed wines more contaminated than rose:and white wines. A good correlation (r = 0.987) was found by comparative analysis of 20 naturally contaminated sa mples using this method and the method of Zimmerli and Dick with better rec overies of OA and better performances for the new method. Several advantage s of this method with respect to the actually available methods have been p ointed out, with particular reference to red wine which appears to be the m ost difficult to analyze. (C) 1999 Elsevier Science BN. All rights reserved .