Determination of bucindolol and its major metabolites in plasma by capillary gas chromatography-mass spectrometry.

A method for determining bucindolol, a deuterated analogue and two metabolites in plasma samples is described. Analytes are obtained from plasma by liquid extraction of 1 ml of plasma at pH 10.5 with 7 ml of peroxide-free ether-hexane (4:1). Following derivatization with 50 microliters of N-methyl-N-trimethylsilyl trifluoroacetamide-pyridine (1:1) for 20 min at 65 degrees C the samples are analyzed by capillary column gas chromatography-mass spectrometry with selected-ion monitoring. Quantification is linear over the range 2-500 ng/ml. Single-day precision was typically 6.2% or better for bucindolol and 13% or better for the metabolites.