Identification—
The visible absorption spectrum of the solution from the
Assay preparation,prepared as directed in the
Assay,exhibits maxima and minima at the same wavelengths as that of the
Standard preparation,prepared as directed in the
Assayand concomitantly measured.
Dissolution á711ñ—
Medium:
pH7.5phosphate buffer (see under Buffer Solutionsin the section Reagents,Indicators,and Solutions);900mL.
Apparatus 1:
100rpm.
Time:
60minutes.
Procedure—
Determine the amount of C
18H
14N
4O
5Sdissolved from UVabsorbances at the wavelength of maximum absorbance at about 358nm 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 Sulfasalazine RSin the same
Medium.
Tolerances—
Not less than 85%(Q)of the labeled amount of C18H14N4O5Sis dissolved in 60minutes.
Assay—
Weigh and finely powder not less than 20Tablets.Transfer an accurately weighed portion of the powder,equivalent to about 150mg of sulfasalazine,to a 100-mLvolumetric flask,add 50mLof 0.1Nsodium hydroxide,and mix.Dilute with 0.1Nsodium hydroxide to volume,mix,and filter,discarding the first 20mLof the filtrate.Transfer 5.0mLof the filtrate to a 1000-mLvolumetric flask containing about 750mLof water,mix,add 20.0mLof 0.1Nacetic acid,mix,dilute with water to volume,and mix.Concomitantly determine the absorbances of this solution and of a Standard solution of
USP Sulfasalazine RSin the same medium having a known concentration of about 7.5µg per mL,at the wavelength of maximum absorbance at about 359nm,using water as the blank.Calculate the quantity,in mg,of sulfasalazine (C
18H
14N
4O
5S)in the portion of Tablets taken by the formula:
20C(AU/AS),
in which
Cis the concentration,in µg per mL,of
USP Sulfasalazine RSin the Standard solution;and
AUand
ASare the absorbances of the solution from the Tablets and the Standard solution,respectively.