Quantitative Determination of (R)-3-Hydroxybutyl (R)-3-Hydroxybutyrate (Ketone Ester) and Its Metabolites Beta-hydroxybutyrate, 1-3-Butanediol, and Acetoacetate in Human Plasma Using LC-MS

This paper develops and validates two LC-MS methods to measure the ketone ester (R)-3-hydroxybutyl (R)-3-hydroxybutyrate and its metabolites beta-hydroxybutyrate, 1,3-butanediol and acetoacetate in human plasma, one using a C18 column and one using a HILIC column for acetoacetate. Intra- and inter-run accuracy was within 15 percent of nominal concentration and precision was below 15 percent CV for all four molecules. The method also showed non-saturable metabolism of the ketone ester in human plasma at concentrations as high as 5 mM, with human serum albumin contributing to its metabolism.