Determination of bencycloquidium bromide in dog plasma by liquid chromatography with electrospray ionization tandem mass spectrometry.

A rapid, selective and sensitive liquid chromatography/tandem mass spectrometry (LC-MS/MS) method was developed and validated for determining bencycloquidium bromide (BCQB) in beagle dog plasma. The plasma sample was deproteinized with methanol which contained l-ethyl-bencycloquidium bromide as internal standard, and supernantant was assayed by LC-MS/MS. The chromatographic separation was performed on a Phenomenex C(18) column (100 x 2.0 mm, i.d., 3.0 microm) with a gradient programme mobile phase consisting of methanol and ammonium acetate (5 mm) containing 0.15% acetic acid and at a flow rate of 0.3 mL/min. Electrospray ionization in positive ion mode and selective reaction monitoring was used for the quantification of BCQB with a monitored transitions m/z 330.2 --> 142.1 for BCQB and m/z 344.2 --> 126.2 for IS. Validation results indicated that the lower limit of quantification was 0.05 ng/mL and the assay exhibited a linear range of 0.05-10.0 ng/mL and gave a correlation coefficient of 0.9998. The intra- and inter-run precisions of the assay were 1.7-4.6 and 3.2-15.6%, respectively, and the intra- and inter-day accuracies were -8.8 to 1.1 and -5.0 to 4.6%, respectively. The developed method was applied for the pharmacokinetic study of BCQB in beagle dogs following a single intranasal dose.