Greenness Assessment of HPLC-UV Method for Simultaneous Estimation of Four Antihypertensive Drugs

An environmentally friendly HPLC method was developed to estimate angiotensin receptor blocker (telmisartan) and calcium channel blockers (cilnidipine, benidipine and azelnidipine) in a single run. Separation was achieved using a C18 column (250 mm × 4.6 mm, 5 μm), employing an eluent consisting of 10 mM potassium phosphate buffer (pH 5), methanol and acetonitrile in a ratio of (25:45:30, v/v/v) at 1.0 mL/min flow. Validation of the method was confirmed, following ICH guidelines. Calibration graphs were found to be linear in the ranges of 2.5-40, 0.625-10, 0.5-8 and 1-16 μg/mL corresponding to telmisartan, cilnidipine, benidipine and azelnidipine, respectively. To assess the environmental impact of the method, five greenness evaluation criteria, namely, the Green Analytical Procedure Index, Analytical GREEness, Chlortox Scale, Blue Applicability Grade Index, and Red-Blue-Green 12, were adopted. Concerning all the tools, the proposed method was found to be green.