A simple liquid chromatography-differential ion mobility spectrometry-tandem mass spectrometry method for the determination of trimethylamine-N-oxide in human serum: An application in dialysis patients.

RATIONALE Trimethylamine-N-oxide (TMAO) is a potential indicator of cardiovascular disease and chronic kidney disorders. It is important to monitor the TMAO level in plasma or serum in hemodialysis patients. A simple liquid chromatography-differential ion mobility spectrometry-tandem mass spectrometry (HPLC/DMS-MS/MS) method was established and validated for the determination of TMAO in the serum of hemodialysis patients. METHODS Chromatographic separation was performed on a Waters Atlantis HILIC silica column (2.1 × 50 mm, 3 μm). The gradient mobile phase consisted of 10 mM ammonium formate buffer and acetonitrile with 0.1% formic acid in both solvents. The serum sample was precipitated with acidic acetonitrile prior to HPLC/DMS-MS/MS analysis and trimethylamine N-oxide-d9 was used as the internal standard (IS). Data acquisition was performed in positive ion mode with a differential mobility spectrometry (DMS) system before the electrospray ionization (ESI) source. The multiple reaction monitoring (MRM) transitions were m/z 76.0→58.0 and m/z 85.2→66.1 for TMAO and the IS, respectively. RESULTS Excellent linearity was observed over the calibration range of 0.05~20 μg/mL (r2 >0.995). The method was validated for good specificity and sensitivity. The inter-run and intra-run precision and accuracy were less than 13.6% and 10.7%, respectively. CONCLUSIONS we established a novel and robust HPLC/DMS-MS/MS method for the quantification of TMAO in human serum sample. The validated assay was simple, rapid, sensitive and reliable. The developed method could be applied to the assay of serum samples from the patients with kidney disease who underwent hemodialysis.