Quantitative determination of the beta-adrenoceptor stimulant formoterol in urine by gas chromatography mass spectrometry.

A method for the quantitative determination of the beta-stimulant formoterol in urine, using a gas chromatograph--mass spectrometer, is described. Formoterol can be analyzed after the addition of a deuterium-labelled internal standard and conversion to a mixed bis-pentafluoropropionyl-methyl derivative for selected ion monitoring. The detection limit was 5 ng/ml. Urinalysis after the oral administration of formoterol fumarate, using a combined enzymic hydrolysis method, revealed that the drug was conjugated with glucuronic acid in rats, dogs and humans.