Rapid and automatable determination of ochratoxin A in wine based on microextraction by packed sorbent followed by HPLC-FLD

The development of miniaturized and automatized analytical methods for OTA determination, requiring a reduced use of solvents and a limited involvement of expert operators, is highly desirable. Therefore, a rapid and automatable method for the determination of OTA in wine using a microextraction by packed C18 sorbent followed by high performance liquid chromatography with fluorescence detection was developed and validated for a successful application in the context of wine production. Important experimental parameters, such as sample and eluent volumes, extraction mode, draw and dispense speeds, number of eluent passes up and down through the stationary phase, were optimized. The validation included the comparison of the sensitivities related to solvent-matched, matrix-matched and standard addition calibrations and the participation to a proficiency test in a inter-laboratory circuit. Matrix effects were also investigated. Accuracies relevant to real samples were estimated to range between 76 and 100%, at 0.2 μg/L, and between 84 and 108%, at 1.0 μg/L, in compliance with the EU Regulation 401/2006; the limits of detection and quantification were of 0.08 and 0.24 μg/L, respectively, i.e. much lower than the maximum level currently permitted for OTA in the European Union (2.0 μg/kg, corresponding to ca 2.0 μg/L). 60 different wines produced in the Foggia (Italy) area were analyzed for their OTA content using the developed method and none of them was found to overcome the maximum permitted limit.