Determination of tryptophan and its kynurenine pathway metabolites in human serum by high-performance liquid chromatography with simultaneous ultraviolet and fluorimetric detection.

An isocratic reversed-phase high-performance liquid chromatographic method for the simultaneous determination of tryptophan and four metabolites of the kynurenine pathway (kynurenine, 3-hydroxykynurenine, kynurenic acid and 3-hydroxyanthranilic acid) in human serum is described. This new method, which uses both isocratic elution and two on-line connected programmable ultraviolet and spectrofluorimetric detectors, allows the determination of these metabolites, in the physiological ranges, with satisfying specificity and sensitivity within 30 min.