Triethylamine buffer , Solution A, Solution B, Mobile phase, Resolution solution, and Chromatographic system—Prepare as directed in the test for Chromatographic purity under Vancomycin Hydrochloride.

Test preparation A— Prepare a solution of Vancomycin Hydrochloride for Injection in Solution A containing 10 mg of vancomycin per mL.

Test preparation B— Transfer 2.0 mL of Test preparation A to a 50-mL flask, dilute with Solution A to volume, and mix.

Procedure— Proceed as directed for Procedure under Vancomycin Hydrochloride. Not less than 88.0% of vancomycin B is found, and not more than 4.0% of any peak other than the main peak is found.

Assay preparation 1 (for determining the µg of vancomycin equivalent per mg)—Dissolve a suitable quantity of Vancomycin Hydrochloride for Injection, accurately weighed, in water, and dilute quantitatively with water to obtain a solution containing about 1 mg of vancomycin per mL.

Assay preparation 2 (where it is represented as being in a single-dose container)—Constitute a container of Vancomycin Hydrochloride for Injection in a volume of water, accurately measured, corresponding to the volume of diluent specified in the labeling. Withdraw all of the withdrawable contents, using a suitable hypodermic needle and syringe, and dilute quantitatively with water to obtain a solution containing about 1 mg of vancomycin per mL.

Assay preparation 3 (where the label states the quantity of vancomycin in a given volume of constituted solution)—Constitute a container of Vancomycin Hydrochloride for Injection in a volume of water, accurately measured, equivalent to the volume of diluent specified in the labeling. Dilute an accurately measured volume of the constituted solution quantitatively with water to obtain a solution containing about 1 mg of vancomycin per mL.

Procedure— Proceed as directed under Antibiotics—Microbial Assays 81, using an accurately measured volume of the appropriate Assay preparation diluted quantitatively with Buffer No. 4 to yield a Test Dilution having a concentration assumed to be equal to the median dose level of the Standard.