Methods for purifying pteroic acid, analogs of pteroic acid, and derivatives of pteroic acid are described. Methods for synthesizing and purifying conjugates of vitamins, including FITC conjugates of folic acid, folic acid analogs, and derivatives of folic acid and folic acid analogs are also described. Purified forms of pteroic acid, derivatives and analogs of pteroic acid, and conjugates thereof are also described.
