Procedure for content uniformity—

Buffer solution— Dissolve 13.61 g of sodium acetate in about 900 mL of water in a 1000-mL volumetric flask, adjust with glacial acetic acid to a pH of 5.0 while stirring, dilute with water to volume, and mix.

Standard preparation— Dissolve an accurately weighed quantity of USP Vinblastine Sulfate RS in Buffer solution, and dilute quantitatively and stepwise with Buffer solution to obtain a solution having a known concentration of about 40 µg per mL.

Test preparation— Dissolve the contents of 1 container of Vinblastine Sulfate for Injection in an accurately measured volume of Buffer solution to obtain a solution having a concentration between 40 µg per mL and 50 µg per mL.

Procedure— Concomitantly determine the absorbances of the Test preparation and the Standard preparation in 1-cm cells at the wavelength of maximum absorbance at about 269 nm versus the Buffer solution as the blank. Calculate the quantity, in mg, of C46H58N4O9.H2SO4 in the container taken by the formula: in which C is the concentration, in µg per mL, of USP Vinblastine Sulfate RS (corrected for loss on drying) in the Standard preparation; V is the volume, in mL, of Buffer solution taken for the Test preparation; and AU and AS are the absorbances of the Test preparation and the Standard preparation, respectively.

(Official January 1, 2007)

Mobile phase , Standard preparation, System suitability preparation, and Chromatographic system—Prepare as directed in the Assay under Vinblastine Sulfate.

Assay preparation— Pipet a suitable volume of water into each of 5 containers of Vinblastine Sulfate for Injection to obtain a solution in each having a concentration of about 1 mg per mL. Insert the stopper, shake to mix, and combine the solutions from the 5 containers. Quantitatively dilute this solution with water to obtain a solution having a concentration of about 0.4 mg per mL, and mix.

Procedure— Separately inject equal volumes (about 20 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in mg, of vinablastine sulfate (C46H58N4O9. H2SO4) in each container of Vinblastine Sulfate for Injection taken by the formula: in which C is the concentration, in mg per mL, of USP Vinblastine Sulfate RS (corrected for loss in weight) in the Standard preparation; V is the volume, in mL, of the Assay preparation; and rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.