Medium: water; 900 mL.

Apparatus 1: 100 rpm.

Time: 60 minutes.

Procedure— Determine the amount of C22H22N2O8·HCl dissolved from UV absorbances at the wavelength of maximum absorbance at about 345 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 Methacycline Hydrochloride RS in the same Medium.

Tolerances— Not less than 70% (Q) of the labeled amount of C22H22N2O8·HCl is dissolved in 60 minutes.

Mobile phase, System suitability preparation, and Chromatographic system— Proceed as directed in the Assay under Methacycline Hydrochloride.

Standard preparation— Transfer about 28 mg of USP Methacycline Hydrochloride RS, accurately weighed, to a 50-mL volumetric flask, add 10 mL of water, dilute with Mobile phase to volume, and mix.

Assay preparation— Place no fewer than 5 Capsules in a high-speed, glass blender jar containing an accurately measured volume of water, and blend for 3 to 5 minutes to obtain a stock solution having a concentration of about 2.5 mg of methacycline (C22H22N2O8) per mL. Filter, transfer 10.0 mL of the filtrate to a 50-mL volumetric flask, add 10 mL of water, dilute with Mobile phase to volume, and mix.

Procedure— Proceed as directed in the Assay under Methacycline Hydrochloride. Calculate the quantity, in mg, of methacycline (C22H22N2O8) in each Capsule taken by the formula: in which V is the volume, in mL, of water used to prepare the stock solution for the Assay preparation; N is the number of Capsules taken to prepare the stock solution for the Assay preparation; and the other terms are as defined therein.