This general information chapter has been harmonized with the corresponding texts of the European Pharmacopoeia and the Japanese Pharmacopoeia. The harmonized texts of these three pharmacopeias are therefore interchangeable, and the methods of the European Pharmacopoeia and/or the Japanese Pharmacopoeia may be used for demonstration of compliance instead of the present United States Pharmacopeia general information chapter method. These pharmacopeias have undertaken not to make any unilateral change to this harmonized chapter.