Determination of trimethylamine, trimethylamine N-oxide, and taurine in human plasma and urine by UHPLC-MS/MS technique

•We developed a UHPLC-MS/MS method for measurements of TMA, TMAO, and taurine in biological samples.•We studied the effect of pre-analytical conditions (blood material, storage, acidification) on the metabolites.•The effect of renal dysfunction on plasma and urinary markers was investigated.

BackgroundTrimethylamine-N-oxide (TMAO) is produced in the liver from trimethylamine (TMA) and is an important cellular osmolyte and potential atherogenic factor. Taurine is involved in cholesterol metabolism and also serves as a cellular osmolyte. Given their significant biological functions, the development of reliable measurement techniques is crucial to further study their role in health and diseaseMethodsA new ultrahigh performance liquid chromatography-tandem mass spectrometry method was developed and validated for the simultaneous determination of TMA, TMAO, and taurine in plasma and urine. The method consisted of a deproteinization step using methanol/acetonitrile (15:85) that contained 0.2% formic acid and isotope-labeled internal standards. Samples were separated by centrifugation and injected into the UHPLC system. Quantification was conducted using a triple-quadrupole mass spectrometer detector with electrospray ionization interface in positive mode.ResultsThe limits of detection ranged from 0.08 to 0.12 μmol/L. The calibration curves were linear (r ≥ 0.999) over the range examined (0.15-400 μmol/L) for all compounds. The inter- and intra-day coefficients of variations were ≤14.5% for TMA and ≤8% for TMAO and taurine. TMAO and taurine were found to be stable in EDTA plasma for at least 14 months at −70 °C. Mean recoveries ranged from 95% to 109% and the relative matrix effects were ≤4.0%. The method was applied to study physiological and pre-analytical factors in plasma and urine samples.ConclusionsThe new UHPLC-MS/MS method has good accuracy, precision, and recovery. The assay combines simple sample processing with a short run time, making it well suited for high-throughput routine clinical or research purposes.