A Developed High-Performance Thin-Layer Chromatographic Method for the Determination of Orlistat in Pharmaceutical Preparations

A sensitive and simple high-performance thin-layer chromatographic method is developed and validated according to the International Conference on Harmonisation (ICH) guidelines. The procedure was applied for the estimation of orlistat in different pharmaceutical preparations. In the proposed method, thin-layer chromatography aluminum sheets pre-coated with silica gel were employed as the stationary phase. A number of solvent mixtures were used as the mobile phase for trials to obtain compact bands of orlistat. The solvent mixture consisting of chloroform and methanol (98:2) was found to be the best. The data obtained from the calibration curves of standard orlistat showed a good linear relationship over the concentration range of 1000-3800 ng per band with respect to the area. Scanning was performed at lambda = 200 nm, where the correlation coefficient (R-2) was 0.970, and the linear regression equation was found to be: y = 4.1419x - 4181.1. After revealing of the spots by anisaldehyde-conc. sulfuric acid, compact violet bands were obtained and, accordingly, scanning was performed at lambda = 600 nm, where a good linear relationship over the concentration range of 600-4000 ng per band with respect to the area was obtained. The correlation coefficient (R-2) was 0.991 with a linear regression equation: y = 4.025x - 1159.3. The method was evaluated regarding accuracy, precision, limits of detection and quantification, and robustness. Revealing of the spots by anisaldehyde-conc. sulfuric acid improved the sensitivity of the method and increased the range within which a linear relationship between concentration and response occurs.