Alginic acid sodium salt

Digitoxigenin and olive oil (highly refined, low acidity) were purchased from Sigma-Aldrich (St. Louis, MO, USA). Alginic acid sodium salt (low viscosity) was from MP Biomedicals (Solon, OH, USA). Tween 85 (Acros Organics, Morris, NJ, USA) and Span 85 (Sigma-Aldrich, St. Louis, MO, USA) were used in the preparation of Digitoxigenin formulations. Other reagents used were isooctane (Acros Organics, Morris, NJ, USA) and calcium chloride dehydrate (Fisher Scientific, Springfield, NJ, USA). Phosphate buffered saline (PBS) of pH 7.4 was prepared by dissolving PBS tablets (MP Biomedicals, Solon, OH, USA) in deionized water, and sodium azide (Acros Organics, Morris, NJ, USA) was added at a concentration of 0.02% (w/v) as a bacteriostat. High performance liquid chromatography (HPLC) grade methanol, water, and formic acid were purchased from Fisher Scientific (Pittsburgh, PA, USA).