Assay
Mobile phase
and Chromatographic systemProceed as directed in the Assayunder Sulfaquinoxaline.
Standard preparation
Dissolve an accurately weighed quantity of
USP Sulfaquinoxaline RSin 0.01Nsodium hydroxide to obtain a solution having a known concentration of about 0.7mg per mL.Dilute an accurately measured volume of this solution quantitatively with water to obtain a solution having a known concentration of about 0.15mg per mL.
Assay preparation
Transfer an accurately measured volume of Oral Solution,equivalent to about 300mg of sulfaquinoxaline,to a 2000-mLvolumetric flask,dilute with water to volume,and mix.
Procedure
Separately inject equal volumes (about 8µL)of the
Standard preparationand the
Assay preparationinto the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the quantity,in mg,of sulfaquinoxaline (C
14H
12N
4O
2S)in each mLof the Oral Solution taken by the formula:
2000(C/V)(rU/rS),
in which
Cis the concentration,in mg per mL,of
USP Sulfaquinoxaline RSin the
Standard preparation,
Vis the volume,in mL,of Oral Solution taken to prepare the
Assay preparation,and
rUand
rSare the sulfaquinoxaline peak responses obtained from the
Assay preparationand the
Standard preparation,respectively.