Figure 4: HPLC chromatogram on Hypersil BDS C-18 (25cm) Column and mobile phase consisted of (A) acetonitrile and (B) phosphate buffer pH=3.5 in variable ratio where a- A: B=55:45 b- A: B=50:50 c- A: B=45:55 d- A: B=40:60 e- A: B=35:65 f- A: B=25:75 for trials to separate Losartan potassium(LOS), Irbesartan (IRB), Valsartan (VAL) and Telmisartan (TELM) respectively.