Simultaneous determination of thirteen beta-blockers and one metabolite by gradient high-performance liquid chromatography with photodiode-array UV detection.

A new rapid and sensitive high-performance liquid chromatography (HPLC) method has been developed for the simultaneous identification and quantification in human plasma of the 13 most commonly prescribed beta-blockers and one active metabolite-atenolol, sotalol, diacetolol, carteolol, nadolol, pindolol, acebutolol, metoprolol, celiprolol, oxprenolol, labetalol, propranolol, tertatolol and betaxolol. It involves liquid-liquid extraction procedures followed by liquid chromatography coupled to photodiode-array UV detection with a fixed wavelength at 220 nm for quantification. Compounds were separated on a 5 microm Hypurity C(18) (ThermoHypersil) analytical column (250 mm x 4.6 mm, i.d.) using a gradient of acetonitrile-phosphate buffer pH 3.8 at a flow rate of 1.0 ml/min. The total analysis time was 26 min per sample. Extraction recoveries were between 74 and 113% for the polar compounds and between 20 and 56% for the most apolar compounds. Calibration lines were linear in the range from 25 to 1000 ng/ml for all compounds excepted carteolol and nadolol (50-1000 ng/ml), all of them with coefficients of determination (r2 values) >/=0.994. Limits of detection (LODs) ranged from 5 to 10 ng/ml. Intra-assay and inter-assay precision and accuracy were studied at two concentration levels (100 and 500 ng/ml). The intra-assay coefficients of variation (CVs) for all compounds were </= 8.3% and all inter-assays CVs were below 12.6%. The intra-assay and inter-assay accuracies for all compounds were found to be within 91.4 and 105.6% at 100 ng/ml and within 94.1 and 107.4% at 500 ng/ml. Thus, the performance of the method described allows its use in toxicological screening and in quantification of the most prescribed beta-blockers drugs.