Figure 5: Typical HPLC chromatograms obtained from 20 μl injections of Amlodipine Besylate Amlodipine impurity A, B, Atorvastatin Calcium, Atorvastatin impurity A and C under chromatographic conditions of mobile phase consisted of acetonitrile 35%: phosphate buffer 65% (different PH) was pumped on Phenomenex kinetex 2.6 u C18 100A columns at a flow rate 1.2 ml/min and detected at 240 nm at constant temperature 40°C.