Gemfibrozil is used to lower cholesterol and triglyceride levels in the blood and Ibuprofen is a common over-the-counter painkiller. Fast separations of these two compounds are obtained on short 50 mm columns. Both Primesep B2 and Primesep D separate by a combination of anion exchange and reversed phase. Retention times on Primesep B2 can be adjusted by changing the percentage of acetonitrile. On Primesep D retention times can be changed by adjusting the percentage of acetonitrile and acetic acid in the mobile phase. The HPLC separations use a mobile phase of water, acetonitrile (MeCN, ACN), ammonium formate and acetic acid (HOAc) with UV detection at 270 nm.