Synchronous Spectrofluorimetry Coupled with Third-Order Derivative Signal Processing for the Simultaneous Quantitation of Telmisartan and Chlorthalidone Drug Combination in Human Plasma.

This study is the first to develop and optimize a method for the simultaneous determination of chlorthalidone (CLT) and telmisartan (TEL) in, human plasma samples as well as in their newly released pharmaceutical tablet form, (Telmikind-CT 40®). The method is based on measuring fluorescence intensity, employing synchronous fluorescence mode coupled to third-order derivative signal processing, 0.5% w/v cetyl trimethyl ammonium bromide was used as cationic surfactant to enhance the fluorescence signal intensity and improve method sensitivity. The third-order derivative synchronous spectra of CLT and TEL are well separated with two zero-crossing points which allowed for the determination of CLT and TEL at 362 nm and 351 nm, respectively. Different experimental parameters were carefully investigated and optimized, calibration curves were constructed over concentration ranges of 20-1200 ng.mL-1 and 5-800 ng.mL-1 for CLT and TEL respectively. The developed method is simple and rapid, analytical parameters were validated according to ICH guidelines and high sensitivity was achieved as represented by limits of detection (LOD) of 4.69 and 1.58 ng.mL-1 for CLT and TEL respectively.