Assessment of the greenness of spectrophotometric and micellar liquid chromatographic methods using two approaches: Application to pharmaceutical analysis of hydrochlorothiazide and telmisartan

Recently the focus of analytical community is to eliminate or reduce the usage of hazardous chemicals; consequently, two ecofriendly, rapid, selective and cost-effective methods are developed for the simultaneous determination of hydrochlorothiazide (HCZ) and telmisartan (TEL). The first method is based on micellar high pressure liquid chromatography using an ecofriendly micellar mobile phase consists of 0.06 M sodium dodecyl sulfate (SDS), 12% v/v n-propanol and 0.3% v/v triethylamine (TEA) at pH 6.0 pumped at a flow rate of 2 mL/min. Rivaroxaban (RIV) is used as an internal standard (I.S). The method gives linear correlation over concentration ranges of 0.8-20.0 mu g/mL and 1.0-20.0 mu g/mL for HCZ and TEL, respectively. The mean percentage recovery for HCZ is 100.60 +/- 0.92 while for TEL is 100.07 +/- 1.16. The second method is based on absorbance ratio (Q-absorbance) technique which depends on measuring the absorbance at two certain wavelengths, one of which is the isoabsorptive point and the other is the lambda(max) of one of the two drugs. Methanolic solutions of HCZ and TEL show their isoabsorptive points at 264.6 nm and 277.3 nm while the lambda(max) of HCZ in methanol is 270 nm. The two drugs obey Beer-Lambert law over the concentration ranges of 1.0-20.0 mu g/mL for HCZ and TEL, respectively. For HCZ, the mean percentage recovery is 99.86 +/- 0.87 while for TEL it is 99.83 +/- 0.94. The spectrophotometric method does not need the addition of any chemical reagents and is carried out without heating or extraction steps. Both methods are successfully applied to the analysis of both drugs in their combined tablets. The results are validated according to official guidelines. Statistical evaluation of the results achieved by the developed and comparison official methods confirms the high accuracy and precision of the developed methods as indicated by student t-test and variance ratio F-test, respectively. Moreover, the greenness of the developed methods is assessed using suitable analytical Eco-Scale and greenness profile, and comparison with the previously published methods has been carried out to indicate priority of the proposed procedures.