Identification—
Transfer a quantity of Capsule contents,equivalent to about 500mg of salsalate,to a stoppered glass test tube.Add 20mLof ether to the tube,close the tube tightly,shake by mechanical means for 10minutes,and filter.Evaporate the filtrate to dryness using a stream of nitrogen:the IRabsorption spectrum of a mineral oil dispersion of the residue thus obtained,exhibits maxima only at the same wavelengths as that of a similar preparation of
USP Salsalate RS.
Limit of salicylic acid—
Mobile phase,Diluent,Resolution solution,and Chromatographic system—
Proceed as directed in the Assay.
Standard preparation—
Dissolve an accurately weighed quantity of
USP Salicylic Acid RSin
Diluentto obtain a stock solution having a known concentration of about 0.5mg per mL.Transfer 3.0mLof this solution to a 100-mLvolumetric flask,dilute with
Diluentto volume,and mix.This solution contains about 0.015mg per mL.
Test preparation—
Use the Assay stock solutionprepared as directed in the Assay.
Procedure—
Proceed as directed for
Procedurein the
Assay,except to inject equal volumes (about 10µL)of the
Standard preparationand the
Test preparation.Calculate the percentage of salicylic acid (C
7H
6O
3)in the portion of Capsules taken by the formula:
10,000(C/OT)(rU/rS),
in which
Cis the concentration,in mg per mL,of
USP Salicylic Acid RSin the
Standard preparation,
OTis the quantity,in mg,of salsalate in the portion of Capsules taken based on the labeled amount,and
rUand
rSare the salicylic acid peak responses obtained from the
Test preparationand the
Standard preparation,respectively:not more than 1.5%is found.
Assay—
Mobile phase
,
Diluent,
Salsalate standard preparation,
Resolution solution,and
Chromatographic system—Proceed as directed in the
Assayunder
Salsalate.
Assay preparation—
Transfer as completely as possible the contents of not less than 20Capsules to a suitable tared container,and weigh.Mix,and transfer an accurately weighed portion of the powder,equivalent to about 100mg of salsalate,to a 100-mLvolumetric flask,dilute with Diluentto volume,and mix.Sonicate for about 10minutes,and mix.Filter a portion of this solution through a suitable filter of 0.5µm or finer porosity.Use the clear filtrate as the Assay stock solution.Transfer 2.0mLof the Assay stock solutionto a 100-mLvolumetric flask,dilute with Diluentto volume,and mix (Assay preparation).
Procedure—
Separately inject equal volumes (about 10µL)of the
Salsalate standard preparationand the
Assay preparationinto the chromatograph,record the chromatograms,and measure the responses for the salsalate peaks.Calculate the quantity,in mg,of salsalate (C
14H
10O
5)in the portion of Capsules taken by the formula:
5000C(rU/rS),
in which
Cis the concentration,in mg per mL,of
USP Salsalate RSin the
Salsalate standard preparation,and
rUand
rSare the responses of the salsalate peaks obtained from the
Assay preparationand the
Salsalate standard preparation,respectively.