My A1 values for L-Arginine/Urea/Ammonia Assay Kit (K-LARGE) blank and samples have an absorbance greater than 1.0. Is it correct for my A1 values to be this high?

The K-LARGE reaction is a negative reaction and therefore it starts with a high absorbance of ~ 1.5 and as the reaction proceeds the absorbance decreases, therefore A2 will be expected to be lower than A1 for samples containing ammonia.  The more ammonia present in the sample the more the absorbance will decrease. The change in absorbance (even though this is a negative change) between readings A1 and A2 corresponds to the amount of ammonia present in the sample.  The same is true for A3 and A4 values with each subsequent reading having a lower absorbance reading than the preceding one. The change in absorbance between readings A2 and A3 corresponds to the amount of urea present in the sample and the change in absorbance between readings A3 and A4 corresponds to the amount of L-arginine present in the sample.  A full description of the calculation required for each analyte is given in the data booklet.

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