Crystalline-orange yellow to yellow brown fine powder. The electrostatic properties of crystalline riboflavin make routine screening difficult. Slightly soluble in water at room temperature. One gram dissolves in 3,000 to 20,000 ml of water. Less soluble in alcohol, insoluble in ether and chloroform.
High potencies tend to be electrostatic.
21 CFR 582.5895. Vitamin Tolerance of Animals, 1987.