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A simple, rapid, and validated thin-layer chromatographic (TLC)-densitometric method has been developed for estimation of labetalol hydrochloride in tablets. Chromatography was performed on aluminum-backed silica gel 60 F254 TLC plates using ethyl acetate-methanol-ammonia (8:2:0.2, v/v/v) as mobile phase. The TLC scanner set at 309 nm was used for direct evaluation of the chromatogram in reflectance absorbance mode. The R F value for labetalol hydrochloride was found to be 0.69 ± 0.02. The validated calibration range was found to be 400–2400 ng per band (r 2 = 0.9910). The method was applied for the determination of labetalol hydrochloride in Lobet-100 tablets. The average percent labeled amount was found to be 99.51 mg per tablet. The percent recovery for labetalol hydrochloride was found in the range of 98.62–100.50% with standard deviation well below 2 indicating accuracy of the method. The suitability of this TLC-densitometric method for quantitative determination of the compound was proved by validation in accordance with the requirements of ICH guidelines. Statistical analysis proved that the method was accurate, precise, and reproducible for analysis of labetalol hydrochloride in tablets.

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Resolution of racemic metoprolol, propranolol, carvedilol, bisoprolol, salbutamol, and labetalol, commonly used β-blockers, into their enantiomers has been achieved by TLC on silica gel plates impregnated with optically pure L -Glu and L -Asp. Acetonitrile-methanol-water-dichloromethane and acetonitrile-methanol-water-glacial acetic acid mobile phases in different proportions enabled successful separation. The spots were detected with iodine vapor. The detection limits were 0.23, 0.1, 0.27, 0.25, 0.2, and 0.2 μg for each enantiomer of metoprolol, propranolol, carvedilol, bisoprolol, salbutamol, and labetalol, respectively.

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Resolution of the enantiomers of racemic atenolol, metoprolol, propranolol, and labetalol, commonly used β-blockers, has been achieved by TLC on silica gel plates using vancomycin as chiral impregnating reagent or as chiral mobile phase additive. With vancomycin as impregnating agent, successful resolution of the enantiomers of atenolol, metoprolol, propranolol, and labetalol was achieved by use of the mobile phases acetonitrile-methanol-water-dichloromethane 7:1:1:1 ( v/v ), acetonitrile-methanol-water 6:1:1 ( v/v ), acetonitrile-methanol-water-dichloromethane-glacial acetic acid 7:1:1:1:0.5 ( v/v ), and acetonitrile-methanol-water 15:1:1 ( v/v ), respectively. With vancomycin as mobile phase additive, successful resolution of the enantiomers of metoprolol, propranolol, and labetalol was achieved by use of the mobile phases acetonitrile-methanol-0.56 mM aqueous vancomycin (pH 5.5) 6:1:1 ( v/v ), acetonitrile-methanol-0.56 mM aqueous vancomycin (pH 5.5) 15:1:2 ( v/v ), and acetonitrile-methanol-0.56 mM aqueous vancomycin (pH 5.5)-dichloromethane 9:1:1.5:1 ( v/v ), respectively. Spots were detected by use of iodine vapor. The detection limits were 1.3, 1.2, 1.5, and 1.4 μg for each enantiomer of atenolol, metoprolol, propranolol, and labetalol, respectively.

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