A simple, selective, precise and stability-indicating high-performance thin-layer chromatographic (HPTLC) method has been developed and validated for analysis of Montelukast sodium (MTKT) and Bambuterol hydrochloride(BAM) both as the bulk drugs and in formulations. The compounds were separated on aluminum-backed silica gel 60 F254 plates with toluene: ethanol: diethyl amine (9: 0.4: 0.6 v/v/v) as mobile phase. This system was found to give compact spots for MTKT and BAM (Rf values 0.43 ± 0.02 and 0.65 ± 0.04, respectively). Densitometric analysis of MTKT and BAM was performed at 266 nm. Regression analysis data for the calibration plots were indicative of good linear relationships between response and concentration over the range of 50–600 ng per spot for MTKT and 100-1200 ng per spot for BAM. The correlation coefficients, r2, were 0.9970 and 0.9950 for MTKT and BAM, respectively. The values of slope and intercept of the calibration plots were 5.942 ± 0.22 and 743.42 ± 51.38 for MTKT and 2.137 ± 0.25 and 381.26 ± 61.11 for BAM, respectively. The method was validated for precision, recovery and robustness. The limits of detection and quantification were 18.0 ± 0.51 and 50 ± 1.05 ng per spot for MTKT and 30 ± 0.63 and 100 ± 1.12 ng per spot for BAM, respectively. MTKT and BAM were subjected to acid, base, peroxide and photo degradation. In stability tests the drugs were susceptible to acid and basic hydrolysis, oxidation and photolytic degradation. Statistical analysis proved the method is repeatable, selective and accurate for estimation of MTKT and BAM because the method could effectively separate the drugs from their degradation products, so it can be used as a stability-indicating method.
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