Determination of ochratoxin A in regional samples of cow's milk from Germany.

Samples (121) of cow's milk from a northern region of Germany were analysed for the occurrence of ochratoxin A by means of a sensitive high-performance liquid chromatographic (HPLC) method. The samples were extracted with a mixture of chloroform and methanol at pH < 2. The extracts were cleaned up by solid-phase extraction on silica gel cartridges. The detection limit was 0.01 ng/ml, the quantitation limit was estimated at 0.03 ng/ml. The mean recovery from spiked samples was 84 +/- 7% in the concentration range of 0.03-0.5 ng/ml. An enzyme-linked immunosorbent-assay (ELISA) was shown to be suitable for the confirmation of ochratoxin A levels down to the detection limit of the HPLC method. No ochratoxin A was detected in the samples analysed, either by HPLC or by ELISA.