Medium: water; 900 mL.

Apparatus 2: 75 rpm.

Time: 60 minutes.

Procedure— Determine the amount of C22H24N2O9 dissolved from UV absorbances at the wavelength of maximum absorbance at about 273 nm of filtered portions of the solution under test, suitably diluted with water, in comparison with a Standard solution having a known concentration of USP Oxytetracycline RS in the same medium, using 5 mL of 0.1 N hydrochloric acid to dissolve the Standard.

Tolerances— Not less than 80% (Q) of the labeled amount of C22H24N2O9 is dissolved in 60 minutes.

Tetrabutylammonium hydrogen sulfate solution , Edetate disodium solution, pH 7.5 Phosphate buffer, Mobile phase, Standard preparation, Resolution solution, and Chromatographic system—Proceed as directed in the Assay under Oxytetracycline.

Assay preparation— Remove, as completely as possible, the contents of not less than 20 Capsules, and mix. Transfer an accurately weighed portion of the powder, equivalent to about 100 mg of oxytetracycline, to a 500-mL volumetric flask, add about 50 mL of 0.01 N hydrochloric acid, and swirl to dissolve. Dilute with 0.01 N hydrochloric acid to volume, mix, and filter a portion of the solution through a 0.5-µm or finer porosity filter. Use the filtrate as the Assay preparation.

Procedure— Proceed as directed for Procedure in the Assay under Oxytetracycline. Calculate the quantity, in mg, of oxytetracycline (C22H24N2O9) in the portion of Capsules taken by the formula: in which the terms are as defined therein.