Sodium Salicylate Tablets
» Sodium Salicylate Tablets contain not less than 95.0 percent and not more than 105.0 percent of the labeled amount of C7H5NaO3.
Packaging and storage Preserve in well-closed containers.
A: Digest a quantity of powdered Tablets, equivalent to about 1 g of sodium salicylate, with 20 mL of water, and filter: the filtrate responds to the flame test for Sodium 191 and to the tests for Salicylate 191.
B: To 10 mL of the filtrate obtained in Identification test A add a slight excess of 3 N hydrochloric acid, collect the precipitate on a filter, wash it with small portions of cold water until the last washing is free from chloride, and dry at about 105 for 1 hour: the salicylic acid so obtained melts between 158 and 161 (see Melting Range or Temperature 741).
Medium: water; 900 mL.
Apparatus 1: 100 rpm.
Time: 45 minutes.
Procedure Determine the amount of C7H5NaO3 dissolved from UV absorbances at the wavelength of maximum absorbance at about 230 nm, using filtered portions of the solution under test, diluted with water, if necessary, in comparison with a Standard solution having a known concentration of USP Sodium Salicylate RS in the same Medium.
Tolerances Not less than 75% (Q) of the labeled amount of C7H5NaO3 is dissolved in 45 minutes.
Uniformity of dosage units 905: meet the requirements.
Assay Place not less than 20 Tablets in a 200-mL volumetric flask, add 100 mL of water, and allow to stand, with frequent agitation, until the tablets disintegrate completely. Dilute with water to volume, and mix. Filter through a dry filter into a dry flask, discarding the first 10 mL of the filtrate. Transfer an accurately measured volume of the subsequent filtrate, equivalent to about 500 mg of sodium salicylate, to a separator, and dilute with water, if necessary, to make about 25 mL. Add 75 mL of ether and 10 drops of bromophenol blue TS, and titrate with 0.1 N hydrochloric acid VS, mixing the water and ether layers by vigorous shaking until a permanent, pale green color is produced in the water layer. Draw off the water layer into a small flask, wash the ether layer once with 5 mL of water, and add this to the water layer. Add 20 mL of ether to the combined water solutions, and mix. Continue the titration with vigorous shaking until a permanent, pale green color is produced in the water layer. Each mL of 0.1 N hydrochloric acid is equivalent to 16.01 mg of C7H5NaO3.
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USP32NF27 Page 3584Pharmacopeial Forum: Volume No. 32(3) Page 825