Enzymatic and immunological approaches for the quantitation and confirmation of ochratoxin A in swine kidneys

Several techniques for the quantitation and confirmation of ochratoxin A (OA) in swine kidneys were examined. Naturally and artificially contaminated swine kidneys were analyzed for OA by conventional high-performance liquid chromatography (HPLC) analysis. Samples were additionally tested by enzyme-linked immunosorbent assay (ELISA) or treated with carboxypeptidase A followed by HPLC analysis (enzymatic method). Correlations (I values) between the conventional HPLC procedure and the ELISA, using artificially contaminated samples, were 0.88 and 0.81 (P <0.05) respectively, while the corresponding values between the conventional HPLC procedure and the enzymatic method were 0.89 and 0.98 (P <0.05). The ELISA gave a more direct estimation of OA contamination than the enzymatic procedure. The enzymatic method also had a reproducible tendency to underestimate or overestimate the amounts of OA in kidney. This was found to be dependent on the source of contamination, as artificially and naturally contaminated kidney samples resulted in linear regression analysis slopes of 0.38 and 2.8, whereas the slopes for the ELISA method were 1.13 and 0.92, respectively. The results with the naturally contaminated kidneys suggest that other naturally occurring forms of OA also occurred in swine kidney. Regardless of this effect, the enzymatic method accurately confirms the presence of OA and related compounds in kidney. The techniques are simple and will complement conventional HPLC analysis for the detection, quantitation, and confirmation of OA in swine kidneys.