Liquid chromatography-mass spectrometric assay for quantitation of the short-chain fatty acid, 2,2-dimethylbutyrate (NSC 741804), in rat plasma

2,2-Dimethylbutyrate (DMB) is a potential treatment for thalassemia and hemoglobinopathies. To facilitate pharmacokinetic evaluation of DMB, we developed an LC-MS assay and quantitated DMB in plasma of rats after an oral dose of 500mg/kg. After acetonitrile protein precipitation, DMB and dimethylvaleric acid (DMV) internal standard were derivatized to benzylamides, chromatographed on a Hydro-RP column with acetonitrile, water, and 0.1% formic acid, and detected by electrospray positive-mode ionization mass spectrometry. The assay was accurate (97-107%) and precise (3.4-6.2%) between 100 and 10,000ng/mL. Recovery from plasma was >62%. Plasma freeze-thaw and room temperature stability were acceptable.