High-Performance Liquid Chromatographic Determination of Atenolol in Tablets

Sensitive spectrophotometric determination of atenolol in pharmaceutical formulations using bromate-bromide mixture as an eco-friendly brominating agent

Three simple and sensitive spectrophotometric methods are proposed for the determination of atenolol (ATN) in bulk drug and tablets. The methods are based on the bromination of ATN by the bromine generated in situ by the action of the acid on the bromate-bromide mixture followed by the determination of unreacted bromine by reacting with a fixed amount of either meta-cresol purple (MCP) and measuring the absorbance at 540 nm (method A) and 445 nm (method B) or erioglaucine (EGC) and measuring the absorbance at 630 nm (method C). Beer's law is valid within the concentration ranges of 1.0-20.0, 2.0-40.0 and 1.0-8.0 μg/mL for method A, method B and method C, respectively. The calculated molar absorptivities were found to be 1.20×10(4), 4.51×10(3) and 3.46 × 10(4)  L/mol · cm for method A, method B and method C, respectively. Sandell's sensitivity values, correlation coefficients, limits of detection and quantification are also reported. Recovery results were statistically compared with those of a reference method by applying Student's t- and F-test. The novelty of the present study is the measurement of two different colors using MCP, that is, red-pink color of MCP in acid medium at 540 nm and yellowish-orange color of brominated MCP at 445 nm.

High-performance liquid chromatography with amperometric detection applied to the screening of beta-blockers in human urine

A high-performance liquid chromatographic method with electrochemical detection has been developed for the determination of six beta-blockers: atenolol, nadolol, timolol, metoprolol, oxprenolol, and alprenolol. The chromatographic separation was performed using a mu Bondapack C18 column, a mobile phase of acetonitrile-water (40:60), containing 5 mM KH2PO4/K2HPO4 proved to be optimal at a 1.3 ml/min flow-rate, and a pH of 6.5. The temperature was optimized at 30 +/- 0.2 degrees C. The amperometric detector, equipped with a glassy carbon electrode, was operated at 1300 mV versus Ag/AgCl in the direct current mode. The method was applied to the determination of these compounds at two concentration levels: ppm and ppb (ng/ml), obtaining relative standard deviations lower than 5% at ppm levels and lower than 10% at ppb levels, and quantitation limits ranging from 15 ppb to 500 ppb. The method was applied to the screening of beta-blockers in spiked urine samples, with a total elution time lower than 12 min, obtaining the best recoveries for timolol and metoprolol (never greater than 93%). These recoveries together with the low limits of quantitation achieved, allows its application to doping analysis in human urine.