Comparative Assessment of ELISA and HPLC for Ochratoxin A Detection in Pork Kidney Samples
Abstract
Introduction: Ochratoxins are mycotoxins produced as metabolites by fungi, in particular Aspergillus and Penicillium. These fungi flourish under special conditions of temperature and humidity.
Aims: The research in this paper was targeted on the optimization of ochratoxin A detection method for animal derived foods in a laboratory pending accreditation (laboratory A). ELISA and HPLC (adapted for animal derived foods) were subjected to a comparative assessment for OTA detection in kidney liver samples within laboratory A. Furthermore, the results were compared with those delivered by an accredited laboratory (B), using GC-MS for OTA detection.
Materials and methods: Two pork kidney samples contaminated with OTA at levels close to MRL were subjected to OTA detection through ELISA (EuroProxima test kit) and HPLC (according to SR EN ISO 15141-1, adapted for animal derived foods) (5 repetitions) within Laboratory A. For precision and accuracy evaluation, the following parameters were calculated: average, interval, standard deviation (SD), relative standard deviation (RSD), confidence interval (CI), standard error from mean, relative average deviation from mean (RADM), relative error, absolute error, repeatability (r). Furthermore, the percent of recovery was calculated for both tested methods using 31 OTA-free pork kidney samples, enriched with increasing concentrations of ochratoxin A.
Results: The comparative assessment of the precision parameters indicates that HPLC adapted for animal derived foods is more appropriate than ELISA for OTA detection in such foods. The following results (in average) were obtained for ELISA and HPLC, respectively: SD=0.16 and 0.04, RSD=0.85 and 0.19, CI= ±0.2 (p<0.05) and ±0.05 (p<0.05), RADM=0.97‰ and 0.79‰, r=0.37 (p<0.05) and 0.13 (p<0.05). The errors calculated using the results delivered by the accredited laboratory were the following: absolute error = -5.01 and -1.06, for ELISA and HPLC, respectively; relative error = -0.2 and -0.043, for ELISA and HPLC, respectively. The average recovery percent was higher for HPLC (95.18%) than for ELISA (78.42%).
Conclusion: Even though ELISA has been considered the preferred method for OTA detection in food and feed, as indicated by the scientific literature, being currently used in many accredited laboratories for OTA detection, these results reveal that HPLC adapted for animal derived foods is more indicated for OTA detection in such products, as it has more precise results and a better repeatability.
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