Optimization of solid-phase clean-up prior to liquid chromatographic analysis of ochratoxin A in roasted coffee

An extraction and clean-up method for ochratoxin A (OA) in roasted coffee has been developed and the HPLC method optimized. An interfering compound with a similar retention time as OA was adsorbed by the aminopropyl (NH2) material at < or = 5% NaHCO3. Residual OA on the column was recovered by washing with the extraction solution followed with methanol. Fractions were mixed together for further clean-up with Ochratest immunoaffinity columns (IACs). Analysis by HPLC resulted in a well resolved OA peak and reduction in matrix interferences. Recoveries ranged from 72 to 84% and the detection limit was 1 ng/g.