Quantitative determination of terbutaline and orciprenaline in human plasma by gas chromatography/negative ion chemical ionization/mass spectrometry

A method for the determination of unconjugated terbutaline and orciprenaline in human plasma is described. The assay is based on stable isotope dilution gas chromatography/negative ion chemical ionization/mass spectrometry. An inexpensive and rapid method for preparation of stable isotope labelled analogues as well as their use in quantitative gas chromatography/mass spectrometry is shown. A highly efficient sample work‐up procedure with product recoveries of more than 95% is presented. The method developed permits quantitative measurement of terbutaline and orciprenaline in human plasma down to 100 pg ml− 1, using 1 ml of sample. Plasma levels of terbutaline after oral administration of 5 mg of terbutaline sulphate were estimated.