The feasibility of the detection and quantitation of β-adrenergic blockers by solid-phase extraction and subsequent derivatization with methaneboronic acid

Urine specimens containing 11 common beta blockers were processed using solid-phase extraction technology to extract the drags from the urine matrix, then converted to their cyclic methaneboronates by treatment with methaneboronic acid in ethyl acetate. The compounds tested included acebutolol, atenolol, alprenolol, bisoprolol, betaxolol, carteolol, penbutolol, propranolol, pindolol, timolol, nadolol, sotalol, labetolol, metoprolol, and oxprenolol. The extraction efficiencies were greater than 90% for all drugs tested. The cyclic methaneboronates formed by this procedure generally possessed good chromatographic properties. The mass spectral behavior of the methaneboronates was excellent, with all compounds containing several high mass fragments and every tested compound possessing a unique mass spectrum.