The determination of terbutaline in human plasma by selected ion monitoring of the t ‐butyldimethylsilyl ether

A method is described for the quantitative determination of terbutaline in 2 ml human plasma. The drug is extracted from plasma as the terbutaline tetraphenylboron ion pair and determined by gas chromatography mass spectrometry of its t ‐butyldimethylsilyl ether. Salbutamol is used as internal standard. Quantification is achieved by selected ion monitoring of the ion m/z 482 derived from t ‐butyldimethylsilyl terbutaline and m/z 495 from t ‐butyldimethylsilyl salbutamol. The detection limit was estimated to be 250 pg terbutaline ml −1 plasma. The coefficient of variation at the level of 1 ng terbutaline ml −1 was 4.1% ( n = 5).