Determination of cystathionine and perhydro-1,4-thiazepine-3,5-dicarboxylic acid in the urine of a patient with cystathioninuria using column liquid chromatography-mass spectrometry.

A method for the measurement of cystathionine and perhydro-1,4-thiazepine-3,5-dicarboxylic acid in the urine of a patient with cystathioninuria has been developed, using column liquid chromatography-mass spectrometry. Cystathionine and perhydro-1,4-thiazepine-3,5-dicarboxylic acid were determined by scanning the [M + H]+ ions of each compound. The recoveries were 80-92.4% for cystathionine and 80-100% for perhydro-1,4-thiazepine-3,5-dicarboxylic acid after ion-exchange treatment. The results agreed well with those obtained using an amino acid analyser. The concentrations found for cystathionine and perhydro-1,4-thiazepine-3,5-dicarboxylic acid were 1.289 +/- 0.099 mg/ml and 0.310 +/- 0.0067 mg/ml, respectively.