Set-up and validation of an adsorptive stripping voltammetric method for kynurenic acid determination in human urine

Validation of an adsorptive stripping voltammetric method for kynurenic acid determination in urine, was presented. The selection of appropriate validation parameters, the design consideration for evaluation and the problem of endogenous metabolites were discussed. The considered fundamental criteria for assessing the reliability and overall performance of the method in the urine matrix were selectivity, linearity and range, limit of quantitation, accuracy, precision and analyte stability. The intermediate precision was also evaluated by means of a full factorial design. An HPLC method with fluorimetric detection was used as a reference method to assess the accuracy. The analysis in urine required a pH control as pointed out by robustness testing and the found kynurenic acid concentration in daily urine ranged from 5 to 40 mu M. (C) 1998 Elsevier Science B.V. All rights reserved.