Identification—
Transfer a quantity of Capsule contents, equivalent to about 500 mg of salsalate, to a stoppered glass test tube. Add 20 mL of ether to the tube, close the tube tightly, shake by mechanical means for 10 minutes, and filter. Evaporate the filtrate to dryness using a stream of nitrogen: the IR absorption 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 RS in
Diluent to obtain a stock solution having a known concentration of about 0.5 mg per mL. Transfer 3.0 mL of this solution to a 100-mL volumetric flask, dilute with
Diluent to volume, and mix. This solution contains about 0.015 mg per mL.
Test preparation—
Use the Assay stock solution prepared as directed in the Assay.
Procedure—
Proceed as directed for
Procedure in the
Assay, except to inject equal volumes (about 10 µL) of the
Standard preparation and 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
C is the concentration, in mg per mL, of
USP Salicylic Acid RS in the
Standard preparation,
OT is the quantity, in mg, of salsalate in the portion of Capsules taken based on the labeled amount, and
rU and
rS are the salicylic acid peak responses obtained from the
Test preparation and 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
Assay under
Salsalate.
Assay preparation—
Transfer as completely as possible the contents of not less than 20 Capsules to a suitable tared container, and weigh. Mix, and transfer an accurately weighed portion of the powder, equivalent to about 100 mg of salsalate, to a 100-mL volumetric flask, dilute with Diluent to volume, and mix. Sonicate for about 10 minutes, and mix. Filter a portion of this solution through a suitable filter of 0.5 µm or finer porosity. Use the clear filtrate as the Assay stock solution. Transfer 2.0 mL of the Assay stock solution to a 100-mL volumetric flask, dilute with Diluent to volume, and mix (Assay preparation).
Procedure—
Separately inject equal volumes (about 10 µL) of the
Salsalate standard preparation and the
Assay preparation into 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
C is the concentration, in mg per mL, of
USP Salsalate RS in the
Salsalate standard preparation, and
rU and
rS are the responses of the salsalate peaks obtained from the
Assay preparation and the
Salsalate standard preparation, respectively.
701
:
30 minutes, simulated gastric fluid TS (without pepsin) being used.