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 500 mg/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 10,000 ng/mL. Recovery from plasma was >62%. Plasma freeze–thaw and room temperature stability were acceptable.