Determination of tebufelone, a new anti‐inflammatory drug, in plasma and tissue using capillary gas chromatography/stable isotope dilution mass spectrometry

A capillary gas chromatographic/mass spectrometric method for the determination of tebufelone, a new anti‐inflammatory drug, in plasma and rat paw tissue is described. Trideuteriated tubufelone was employed as an internal standard and the drug quantified by selected ion monitoring using a mass‐selective detector following positive electron ionization (70 eV). Tebufelone was recovered from plasma (>93%) and pulverized paw tissue (>88%) by ethereal extraction. Standard curves were linear between 5 ng ml −1 and 5 μg ml −1 with a detection limit (S/N = 2) of 2 ng ml −1 . The coefficient of variation for successive injections of standards (200 ng ml −1 ) or samples (10–1500 ng ml −1 ) was 7.3% and 8.5%, respectively.