Medium: 0.01Nhydrochloric acid;900mL.

Apparatus 2: 50rpm.

Time: 60minutes.

Procedure— Determine the amount of total sulfapyrimidines dissolved by employing UVabsorption at the wavelength of maximum absorbance at about 254nm on filtered portions of the solution under test,suitably diluted with 0.01Nsodium hydroxide,in comparison with a Standard solution having approximately equal,known,concentrations of USP Sulfadiazine RS,USP Sulfamerazine RS,and USP Sulfamethazine RSin the same media.

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

Mobile phase ,Standard preparation,and Chromatographic system—Proceed as directed in the Assayunder Trisulfapyrimidines Oral Suspension.

Assay preparation— Weigh and finely powder not less than 20Tablets.Transfer an accurately weighed portion of the powder,equivalent to about 250mg of total sulfapyrimidines,to a 250-mLvolumetric flask,add 50mLof 0.1Nsodium hydroxide,swirl for several minutes to dissolve the sulfapyrimidines,dilute with water to volume,and mix.Filter the mixture,discarding the first several mLof the filtrate.Pipet 3mLof the clear filtrate into a 25-mLvolumetric flask,dilute with water to volume,and mix.

Procedure— Proceed as directed for Procedurein the Assayunder Trisulfapyrimidines Oral Suspension.Calculate the quantity,in mg,of sulfadiazine in the portion of Tablets taken by the formula: in which Cis the concentration,in µg per mL,of USP Sulfadiazine RSin the Standard preparation,and RUand RSare the peak responses obtained from the Assay preparationand the Standard preparation,respectively.Similarly measure the responses of the sulfamerazine and sulfamethazine peaks,and calculate the quantity,in mg,of each in the portion of Tablets taken.