Dronic acids are bisphosphonates that differ in their alkyl chains. Alendronate (Fosamax) marketed alone is used for osteoporosis and other bone diseases. It is also combined with Vitamin C (Fosavance). A short, 50 mm Primesep SB column separates alendronic, ibandronic, and etidronic acids. The HPLC separation uses a mobile phase of water, acetonitrile (MeCN, ACN), trifluoracetic acid (TFA) or ammonium formate and evaporative light scattering detection (ELSD) at 80°C.