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Evaluation of immunoassay kits for determination of ochratoxin A in cereals4.3.5 Blank sample analysisThe results of three blank materials are summarized in (Table 55). The kit gives good results for wheat and winterbarley but it generates an elevated signal for oats..Table 55: Detection limit for three matricesWheat Winter Barley OatsN 9 9 9DF 8 8 8t (95%) 2.31 2.31 2.31SD (ng/g) 0.16 0.09 0.33Q1 (ng/g) 0.20 0.19 1.90Q3 (ng/g) 0.47 0.31 2.20Mean (ng/g) 0.31 0.25 2.08∆xmin (ng/g) 0.12 0.07 0.25Detection limit (ng/g) 0.43 0.32 2.33R-Biopharm remarked correctly that the matrix effect for oat is somewhat higher compared to the wheat and winterbarley. This is in contrast to Table 52 where the difference was not evident. We suspect two reasons could beresponsible for this. Variability in the matrix (solid matrices can be very inhomogeneous) was minimized by poolingthree different extracts but it‟s possible that even this didn‟t cancel out the variability of the matrix. The experimentalset-up of the cross reactivity: used relatively low concentrations of OTA. This could increase the variability of theresponse.4.3.6 ConclusionsCross-reactivity with OTB was not observed with this kit (making it the only one in this review). There wasindication for a slight matrix effect. The kit was easy to use with a very straightforward and cheap extractionprotocol.4-54 Experimental evaluation | CODA-CERVA