Medium: 0.1 N hydrochloric acid; 900 mL.

Apparatus 1: 100 rpm.

Time: 45 minutes.

Procedure— Determine the amount of C22H24N2O9 dissolved from UV absorbances at the wavelength of maximum absorbance at about 353 nm of filtered portions of the solution under test, suitably diluted with Dissolution Medium, if necessary, in comparison with a Standard solution having a known concentration of USP Oxytetracycline RS in the same medium.

Tolerances— Not less than 75% (Q) of the labeled amount of C22H24N2O9 is dissolved in 45 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— Weigh and finely powder not less than 20 Tablets. Transfer an accurately weighed portion of the powder, equivalent to about 100 mg of oxytetracycline, to a 500-mL volumetric flask, add about 25 mL of 0.01 N hydrochloric acid, and mix. Dilute with 0.01 N hydrochloric acid to volume, and mix. Filter a portion of this solution through a 0.5-µm or finer porosity filter, and use the filtrate as the Assay preparation.

Procedure— Proceed as directed for Procedure in the Assay under Oxytetracycline. Calculate the quantity, in mg, of C22H24N2O9 in the portion of Tablets taken by the formula: in which C is the concentration, in mg per mL, of USP Oxytetracycline RS in the Standard preparation, and the other terms are as defined therein.