Targeted UPLC/MS/MS quantification of methylated amines and selected amino acids in biofluids

RATIONALE: Methylated amino compounds and basic amino acids are important analyte classes with high relevance in nutrition, physical activity and physiology. Reliable and easy quantification methods covering a variety of metabolites in body fluids are a prerequisite for efficient investigations in the field of food and nutrition. METHODS: Targeted UHPLC/MS analysis was performed using HILIC separation and timed ESI-MRM detection, combined with a short sample preparation. Calibration in urine and blood plasma was achieved by matrix-matched standards, isotope-labelled internal standards and standard addition. The method was fully validated and the performance was evaluated using a subset from the Karlsruhe Metabolomics and Nutrition (KarMeN) study. RESULTS: Within this method, a number of 30 compounds could be quantified simultaneously in a short run of 9 minutes in both body fluids. It covers a variety of free amino compounds which are present in very different concentrations. The method is easy, precise and robust, and has a broad working range. As a proof of principle, literature-based associations of certain metabolites with dietary intake of respective foods were clearly confirmed in the KarMeN subset. CONCLUSIONS: Overall, the method turned out to be well suited for application in nutrition studies, as shown for the example of food intake biomarkers in KarMeN. Application to a variety of questions such as food-related effects, or physical activity will support future studies in the context of nutrition and health