Ochratest immunoaffinity column

Analysis of OTA in meat samples was conducted as suggested by Jorgenson and Petersen (2002) (link). Extraction solvent (dichloromethane:ethyl acetate, 1:3) (100 ml) was added to a 25 g sample and blended for 1 min. The mixture was filtered using Whatmann #4 filter paper and 10 ml aliquot of the filtrate was evaporated to dryness and the residue re-dissolved in 2 ml methanol and 30 ml PBS buffer (pH 7.4) then further filtered to remove any suspended fat. The filtered solution was then passed through an OchraTest immunoaffinity column (Vicam, Ltd) and the column washed using 20 ml of water. The OTA was eluted from the column using 4 ml of methanol. The extract was evaporated under a stream of air and the residue was reconstituted in 1 ml of water:acetonitrile:acetic acid, 51:48:1 and filtered using 0.2 μm (Nylon membrane) filter discs (Pall, Acro Discs). Samples (100 μl) were injected into a HPLC-fluorescence system for analysis. The parameters used for the HPLC analysis were the same as the ones used for coffee and cocoa analysis. Samples were extracted and analysed in 5 replicates and recoveries calculated. Recovery rates varied from 82.8–111.0% with a limit of detection of 0.22 μg/kg.