Determination of albuterol in plasma after aerosol inhalation by gas chromatography mass spectrometry with selected-ion monitoring

Albuterol is a beta(2)-adrenergic agonist commonly used as a bronchodilator for the treatment of patients with asthma. We have developed an assay to determine plasma levels as low as 50 pg/ml of albuterol by gas chromatography-mass spectrometry (GC-MS). This assay utilizes isotopically labeled albuterol ([C-13]albuterol) as an internal standard. In this assay albuterol and the internal standard are recovered from 1 mi of plasma using solid-phase extraction. The samples are then derivatized to trimethylsilyl ethers using N,O-bis(trimethylsilyl)trifluoro-acetamide with 1% trimethylchlorosilane. The samples are then analyzed by GC-MS with selected-ion monitoring (SIM) for the ions mit 369.15 and 370.15. The method has been validated for a concentration range of 50-10 000 pg/ml in plasma.