High-performance liquid chromatographic–tandem mass spectrometric method for the determination of ethionamide in human plasma, bronchoalveolar lavage fluid and alveolar cells

We have developed and validated an accurate, sensitive, and rapid high-performance liquid chromatographic–tandem mass spectrometric method (HPLC–MS–MS) for the determination of ethionamide in plasma, bronchoalveolar fluid (BAL) and alveolar cells (AC). The retention times for ethionamide, clemastine fumarate (internal standard for plasma), promethazine (internal standard for plasma) and propranolol (internal standard for BAL and AC) were approximately 2.62, 1.21, 2.14, and 2.22 min, respectively, with a total run time of 3.2 min. Ethionamide detection for plasma was carried out on a PE Sciex API III (Perkin-Elmer, Foster City, CA, USA). BAL and cell pellets and some plasma specimens were analyzed on a Micromass Quattro LC (Micromass Co., Manchester, UK). The detection limits for ethionamide were 0.05 μg/ml for plasma, and 0.005 μg/ml for BAL supernatants and alveolar cell suspensions.