Simultaneous determination of trimethylamine and trimethylamine N-oxide in mouse plasma samples by hydrophilic interaction liquid chromatography coupled to tandem mass spectrometry

作者：Mi Si; Zhao Yuan Yuan; Jacobs Rene L; Curtis Jonathan M^*

来源：Journal of Separation Science, 2017, 40(3): 688-696.

DOI：10.1002/jssc.201600926

• derivatization
• hydrophilic interaction chromatography
• tandem mass spectrometry
• trimethylamine
• trimethylamine N-oxide

A method was developed that applies hydrophilic interaction liquid chromatography with tandem mass spectrometry in the multiple reaction monitoring mode to separate and accurately quantify trimethylamine and trimethylamine N-oxide in a single chromatographic run. This was achieved by converting trimethylamine to ethyl betaine, which is less volatile and hence results in greatly improved quantitation. Ethyl betaine also gives a similar response to trimethylamine N-oxide using positive-ion electrospray ionization mass spectrometry. It is readily separated from trimethylamine N-oxide by hydrophilic liquid chromatography in a 5 min run and with improved peak shape compared to underivatized trimethylamine. Validation of the method yielded a limit of detection (S/N >= 3) of 0.5 ng/mL for trimethylamine and 0.25 ng/mL for trimethylamine N-oxide. Method accuracies of 91.4-105.3% with precisions of 0.4-5.5% were obtained for standard mixtures over the range of 2.5-500 ng/mL. Recoveries measured for the extraction of trimethylamine and trimethylamine N-oxide spikes into mouse plasma were both > 90%. The method, which simultaneously measures trimethylamine and trimethylamine N-oxide, was successfully applied to mouse plasma samples and could be adapted for use with other biological fluids.