title: Liquid-chromatographic measurement of amino acids in biological samples after formation of phenylthiohydantoin derivatives.
abstract: In this method for measuring amino acids in urine, serum, and tissue, the amino acids to be assayed and the internal standard, L-norleucine, are converted to phenylthiohydantoins , isolated by organic solvent extraction, separated by reversed-phase "high-pressure" liquid chromatography, and detected by ultraviolet absorbance. The analytes are identified by retention times and quantified by comparing peak heights with that of the internal standard. The peak-height ratios vary linearly with concentrations of 50 to 500 mg/L, corresponding to the concentration range usually found in biological samples. Detection limits are 5 to 20 mg/L. Inter- and intra-assay precision (CV) varies between 1 and 26%. Average analytical recoveries range between 67 and 100%.
mesh_terms: D000596:Amino Acids / Q000032:analysis* / Q000097:blood / Q000652:urine; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003545:Cysteine / Q000032:analysis; D003553:Cystine / Q000032:analysis; D006197:Hair / Q000032:analysis; D006801:Humans; D006827:Hydantoins / Q000032:analysis*; D009646:Norleucine / Q000032:analysis; D010669:Phenylthiohydantoin / Q000032:analysis*; D013056:Spectrophotometry, Ultraviolet
chemical_list: D000596:Amino Acids; D006827:Hydantoins; D010669:Phenylthiohydantoin; D003553:Cystine; D009646:Norleucine; D003545:Cysteine