Sol–gel immunoaffinity chromatography for the clean up of ochratoxin A contaminated grains

This paper describes the application of sol–gel immunoaffinity columns for clean up of ochratoxin A contaminated cereal crops. Monoclonal antibodies selective for OTA have been entrapped into the pores of a sol–gel matrix in order to prepare immunoaffinity columns. Different parameters such as amount of entrapped antibodies and loading conditions were optimized to obtain highest possible recoveries of OTA. The method has been found to be a suitable tool in sample preparation prior to HPLC-FLD determination and as selective as conventional commercially available immunoaffinity columns. In the clean up of different cereals mean recoveries of 82 ± 5%, 90 ± 6% and 91 ± 3%, were obtained for wheat, barley and rye, respectively, with sol–gel columns containing 1 mg of anti-OTA antibodies. The detection limit (signal-to-noise ratio, 3) was 0.5 μg/kg and the limit of quantification (signal-to-noise ratio, 10) determined to be 1 μg/kg. Sol–gel columns can be reused 7 times without significant loss of recovery. After 10 applications the recovery decreased to approx. 50%.