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 bronchodi lator 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 ga s chromatography-mass spectrometry (GC-MS). This assay utilizes isotop ically labeled albuterol ([C-13]albuterol) as an internal standard. In this assay albuterol and the internal standard are recovered from 1 m i of plasma using solid-phase extraction. The samples are then derivat ized to trimethylsilyl ethers using N,O-bis(trimethylsilyl)trifluoro-a cetamide with 1% trimethylchlorosilane. The samples are then analyzed by GC-MS with selected-ion monitoring (SIM) for the ions mit 369.15 an d 370.15. The method has been validated for a concentration range of 5 0-10 000 pg/ml in plasma.