FIRST ORDER DERIVATIVE SPECTROPHOTOMETRIC METHOD FOR SIMULTANEOUS ESTIMATION OF TELMISARTAN AND CHLORTHALIDONE IN BULK AND PHARMACEUTICAL DOSAGE FORM

A simple, precise, and accurate method was developed for the estimation of Telmisartan (TEL) and Chlorthalidone (CHL) in bulk and pharmaceutical dosage form using first order derivative spectrophotometry. Wavelength selected for quantitation were 264.85nm for Telmisartan (zero crossing point of Chlorthalidone) and 222.38nm for Chlorthalidone(zero crossing point of Telmisartan). The method was validated with respect to linearity, accuracy, precision, limit of detection and limit of quantitation in accordance with the International Conference on Harmonisation (ICH) guidelines. Linearity was observed in concentration range of 8-48 μg/ml for Telmisartan and 2.5-15 μg/ml for Chlorthalidone. The limit of detection and limit of quantitation were found to be 0.234μg/ml and 0.712 μg/ml for Telmisartan and 0.102 μg/ml and 0.309 μg/ml for Chlorthalidone. The percentage recovery of Telmisartan and Chlorthalidone was found to be 99.26% and 99.36% respectively. The % R.S.D. values for intra-day and inter-day precision study were <1.0%, confirming that the method was sufficiently precise. The method can be successfully employed for the simultaneous estimation of Telmisartan and Chlorthalidone in pharmaceutical formulations.