High performance liquid chromatographic measurement of bisoprolol in plasma

A simple high performance liquid chromatographic method has been devised for the measurement of bisoprolol in plasma or serum. The sample (200 microL) is vortex mixed for 30 s with 2 M Tris solution (50 microL), aqueous internal standard (benzimidazole, 2.0 mg/L, 50 microL) and methyl t-butyl ether (200 microL). After centrifugation (9950 x g, 2 min), a portion of the resulting extract is analysed on a microparticulate (5 microns) silica column using 1 mM camphorsulphonic acid in methanol as the mobile phase. Detection is by fluorescence at an excitation wavelength of 215 nM. The lower limit of accurate measurement for the assay is 10 micrograms/L (CV% = 8.9, n = 9) with a lower limit of detection of 5 micrograms/L. There is minimal interference from either commonly prescribed drugs or endogenous compounds.