» Gramicidin is an antibacterial substance produced by the growth of Bacillus brevis Dubos (Fam. Bacillaceae). It may be obtained from tyrothricin. It has a potency of not less than 900 µg of gramicidin per mg, calculated on the dried basis.
Packaging and storage Preserve in tight containers.
Identification, Ultraviolet Absorption 197U
Solution: 50 µg per mL.
Melting temperature, Class Ia 741: not lower than 229, determined after drying.
Crystallinity 695: meets the requirements.
Loss on drying 731 Dry about 100 mg in a capillary-stoppered bottle in vacuum at 60 for 3 hours: it loses not more than 3.0% of its weight.
Residue on ignition 281: not more than 1.0%, the charred residue being moistened with 2 mL of nitric acid and 5 drops of sulfuric acid.
Assay Proceed with Gramicidin as directed under AntibioticsMicrobial Assays 81.
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USP32NF27 Page 2528