COMPARISON OF 2 METHODS FOR THE DETERMINATION OF OCHRATOXIN-A IN GREEN COFFEE BEANS

The laboratory of the Biological Chemistry Section of the Adolfo Lutz Institute has been asked to analyze ochratoxin A levels in green coffe e beans exported to Greece and Lebanon since October 1989. The request follows the establishment of a maximum tolerance limit of 20mg/kg of OA for the imported products by these countries. The present study was undertaken to determine the most appropriate method for a routine OA analysis of green coffee beans at the Adolfo Lutz Institute. Two metho ds for ochratoxin A analysis by thin-layer chromatography were compare d, namely AOAC (1990) and the Soares and Rodriguez-Amaya (1985) method as modified by Milanez and Sabino (1989). Accuracy (recovery of spike d samples), precision (day-to-day reproducibility) and practicality (a pplicability cost, speed, equipment and skill requirements, as well as exposure risk) were the parameters used for comparison. The results s howed that both methods are reliable. The coefficients of variation ob tained were less than 30%, which are considered adequate for OA evalua tion and demonstrate a good reproducibility. Recoveries from the spike d samples were over 70% and thus within levels acceptable for mycotoxi n analysis. However, the practicality data indicated that the method o f Soares and Rodriguez-Amaya (1985) as modified by Milanez and Sabino (1989) is more suitable for routine use.