A Novel Approach: Effect of polarity Index of mobile phase on Retention Time of Antihyperlipidemic Antihypertensive and Angiotensin inhibiting Drugs in RP-HPLC Method

The present research was dedicated to know polarity index of mobile phase (instead of stating mobile phase composition) and to study its effect, on the retention time of drugs. Objective of present research was to optimize compatible mobile phase able to separate many drugs simultaneously. Common approach adopted to optimize mobile phase is by variation in mobile phase composition, during development of analytical, bio analytical liquid chromatographic techniques. Polarity index is the cumulative term for the polarity of all solvents and their proportion constituting mobile phase. Solvents acetonitrile, methanol and water were used in varying composition and Polarity index was calculated as arithmetic sum of polarity of each solvent and volume fraction of each solvent in mobile phase. Effect of polarity index of mobile phase on some antihyperlipidemic drugs like simvastatin (SIM), rosuvastatin (RV), fluvastatin (FV) and ezetimibe (EZE); angiotensin inhibiting drug like valsartan (VAL), and anti-hypertensive drugs amlodipine besylate (AMB) and lercanidipine HCl (LC) were studied in this RP-HPLC technique. The separated eluents were monitored by keeping UV detector at suitable wavelength where all drugs shows well absorption. The study proved polarity index and pH of solvent has marked effect on retention time of drugs and system suitability parameters in the chromatography. This was beneficial in optimization of the mobile phase for weakly acidic or basic drugs; and necessity of pH adjustment in many instances. Mobile phase with polarity index 7.586 (acetonitrile: water 60:40%v/v) and 6.1386 (methanol: water 80:20%v/v) were efficient in distinct separation of many drugs simultaneously in this study. This study proved that efficient and compatible mobile phase was capable in separation and simultaneous detection of many drugs, saves time to restore chromatographic conditions on mobile phase changeover.