Document - FAVV

Evaluation of immunoassay kits for determination of ochratoxin A in cereals4.5 OCHRATOXIN-A ELISA by Europroxima4.5.1 Concentration accuracy of standardsThe kit of Europroxima is supplied with 7 ready to use standard solutions with a concentration ranging from 0(blank) to 8 ng/ml OTA, corresponding to a concentration of 0 to 40 ng OTA per gram cereal. The results,summarized in Table 63, don‟t highlight any anomalies in the standards.Table 63: Accuracy of calibrantsCalibrant (ng/g) LC-MS/MS (ng/g) % Dev T-Test0.00 0.00 / 0.870.25 0.29 160.50 0.61 231.00 1.18 182.00 2.34 174.00 4.50 128.00 8.80 104.5.2 Cross-reactivity4.5.2.1 SolventThe cross-reactivity was checked on 7 different concentrations, corresponding to the OTA concentrationEuroproxima uses in its kit for 8 components and compared to the extinction of OTA. The solvent used was theproprietary dilution buffer supplied with the kit. From Table 64 and Figure 14 it is clear that OTB interacts stronglywith the anti-bodies. For the other components the IC 50 was virtually non-existing.Table 64: Cross-reactivity in solventOTA OTB Otα CIT ZEA AFLA B1 COU 4-HC PheSlope -0.541 -1.046 -0.281 0.266 0.056 -0.251 0.035 -0.186 -0.121Intercept 0.556 0.080 1.105 0.761 0.648 1.026 0.468 0.735 0.606R 2 0.965 0.988 0.548 0.189 0.200 0.830 0.068 0.538 0.241SE Intercept 0.051 0.057 NR NR NR NR NR NR NRSE Slope 0.051 0.057 NR NR NR NR NR NR NRIC50 (ng/g) 10.677 1.193 8608.887 732.598 3.1E+11 1.2E+04 1.8E+13 8.9E+03 9.9E+04Relative Crossreactivity 100% 895% 0% 1% 0% 0% 0% 0% 0%CODA-CERVA | Experimental evaluation 4-59