Selected ion monitoring assay for the bronchodilator pirbuterol

A selected ion monitoring assay has been developed to measure plasma levels of the bronchodilator pirbuterol in animals and man. Pirbuterol is extracted from plasma with acetone + potassium carbonate and after further purification is converted to its trimethylacetyl derivative. With the use of the stable isotope labeled internal standard, pirbuterol‐d9, precisions of 10% and 6% were achieved at plasma concentrations of 1 and 20 ng ml−1, respectively. The synthesis of the deuterium labeled internal standard is described.