A 9-Month-Old Boy with Seizures and Discrepant Urine Tryptophan Concentrations/Commentary/Commentary

An inherent limitation of the Hitachi L-8800 amino acid system-and platforms based on liquid chromatography and spectrophotometry in general-is that analyte identification is based on retention times within the chromatographic system deployed. [...] quantification may be compromised by interfering analytes coeluting with the analyte of interest. The presumptive presence of this AED in the urine of our patient was further confirmed by adding increasing amounts of vigabatrin (i.e., 0, 500, 1500, and 7500 µmol/g creatinine) into aliquots of a control urine sample before UV analysis by the automated liquid chromatography amino acid analyzer.