Ochratoxin A in dried vine fruit: method development and survey

Abstract

A method is described for the determination of concentrations of the mycotoxin ochratoxin A in dried vine fruits (currants, raisins and sultanas) using acidic methanolic extraction,immunoaffinity chromatography clean-up and HPLC determination. The limit of detection was estimated as 0.2μg/kg, and recoveries of 63-77% were achieved at 5μg/kg. HPLC-mass spectrometric confirmation of the identity of ochratoxin was obtained. Ochratoxin A and aflatoxins were determined in 60 samples of retail dried vine fruits purchased in the United Kingdom. Ochratoxin A was found in excess of 0.2μg/kg in 19 of 20 currant, 17 of 20 sultana and 17 of 20 raisin samples examined, an overall incidence of 88%. The maximum level found was 53.67μg/kg. No aflatoxin was found in any sample analysed, using a method with a detection limit of 0.2μg/kg for each of aflatoxin B₁, B₂, G₁ and G₂.