Packaging and storage—
Preserve in tight containers.
Labeling—
Label it to indicate that it is for veterinary use only. Label it to state the content of bacitracin in terms of grams per pound, each gram of bacitracin being equivalent to 42,000 Bacitracin Units.
Loss on drying 
731
—
Dry about 100 mg, accurately weighed, in a capillary-stoppered bottle in vacuum at a pressure not exceeding 5 mm of mercury at 60
for 3 hours: it loses not more than 5.0% of its weight.
Zinc content—
Using Powder, proceed as directed for
Zinc content under
Bacitracin Zinc. Calculate the zinc content, in g, in relation to each 42,000 Bacitracin Units in the specimen taken by the formula:
280,000C / WA,
in which
A is the bacitracin content of the specimen, in Bacitracin Units per g, and the other terms are as defined therein: it contains not more than 2.0 g for each 42,000 Bacitracin Units.
Assay—
Dissolve an accurately weighed quantity of Powder quantitatively in 0.01 N hydrochloric acid to obtain a stock solution containing about 100 Bacitracin Units per mL. Proceed as directed under
Antibiotics—Microbial Assays 81, using an accurately measured volume of this stock solution diluted quantitatively and stepwise with
Buffer No. 1 to obtain a
Test Dilution having a concentration assumed to be equal to the median dose level of the Standard. In preparing each test dilution of the Standard, add additional hydrochloric acid to each to obtain the same concentration of hydrochloric acid as in the
Test Dilution.
