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Evaluation of immunoassay kits for determination of ochratoxin A in cerealsinterest were subsequently constructed in the extracts. Besides these modifications the same protocol was used as in4.1.4.2.1.4.1.4.2.2.2 Data handling and statistical analysesThe same protocol was used as described in 4.1.4.2.1.2.4.1.4.3 Work package III: Matrix effect4.1.4.3.1 Study designTo assess the matrix effect a calibration curve of OTA is constructed in pure extraction solvent, in extract of amatrix (wheat, winter barley and oats) and in extract diluted 5 times with pure extraction solvent (see Table 41). Forall kits, the same sample of wheat, winter barley and oats was used. The extracts were pooled to minimize matrixinhomogenity.Table 41: Example of dilution scheme for matrix affect (calibration curve with 4 points)Control Water+std (9:1)Wheat Undiluted Extract+Std (9:1)Diluted Extract +std (9:1)Winter barley Undiluted Extract+Std (9:1)Diluted Extract +std (9:1)Oats Undiluted Extract+Std (9:1)Diluted Extract +std (9:1)Concentration 1 Concentration 2 Concentration 3 Concentration 4It is very well known in the art that mycotoxin identification and quantification can be hampered by matrix effects.Immunoassays are no exception to this. One common way to overcome the detrimental effects of matrixcompounds is to dilute the sample, implying the assumption that less matrix means less matrix effect. Diluting hassome drawbacks: it might increases significantly the LOD and LOQ as the component of interest is also diluted.Moreover it introduces an extra manipulation step (pipetting) whose error is afterwards multiplied by the dilutionfactor. Matrix effects are considered to be significant when higher than 10% compared to the solvent 69 .Matrix effect may be defined as the sum of the effects of all the components in a system with the exception of theanalyte to be measured 70 (see also Equation 11).4.1.4.3.2 Data handling and statistical analyses4.1.4.3.2.1.1 Elisa kitsDose-response curves were constructed by plotting the theoretical concentration against the relative absorbance(B/Bo).Two methods can be used to assess the matrix effect.69 Lee NA, Wang S, Allan RD, Kennedy IR. J Agric Food Chem. 2004 May 19; 52(10):2746-55.70 Wood WG, Matrix effects in immunoassays, Scand. J. Clin. Lab. Invest. Suppl., 1991, 205, 1054-42 Experimental evaluation | CODA-CERVA