A flow injection electrospray ionization tandem mass spectrometric method for the simultaneous measurement of trimethylamine and trimethylamine N-oxide in urine.
Key metabolites for the diagnosis of the genetic disorder trimethylaminuria are trimethylamine (TMA) and trimethylamine N-oxide (TMAO). A rapid, automatable flow injection ESI-MS/MS method for their measurement in urine has been developed. The TMA was derivatized with ethyl bromoacetate to form ethyl betaine bromide. The 2 min ESI-MS/MS analysis employed four multiple reaction monitoring (MRM) ion pairs for derivatized TMA (146.1, 118.1), derivatized (2)H(9)-TMA (155.1, 127.1), TMAO (76.1, 58.1) and (2)H(9)-TMAO (85.1, 66.1). In control urine samples (n = 27) referred for suspected metabolic problems TMA was 0.11-1.19 mmol/mol creatinine, TMAO was 13.5-181 mmol/mol creatinine and the TMA/TMAO ratio was 0.0025-0.055. In five patients with diagnosed trimethylaminuria, TMA was 5.3-230 mmol/mol creatinine, TMAO was 0.36-607 mmol/mol creatinine and the TMA/TMAO ratio was 0.20-134.
Johnson
David W
DW
Department of Genetic Medicine, Women's and Children's Hospital, 72 King William Road, North Adelaide, South Australia 5006, Australia. david.johnson@adelaide.edu.au
D006801:Humans; D008661:Metabolism, Inborn Errors / Q000175:diagnosis / Q000652:urine*; D008744:Methylamines / Q000032:analysis / Q000652:urine*; D009812:Odorants; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
D008744:Methylamines; C005855:trimethyloxamine; C023336:trimethylamine