A: Digest a quantity of finely powdered Tablets,equivalent to about 50mg of codeine sulfate,with 15mLof water and 5mLof 2Nsulfuric acid for 1hour.Filter,if necessary,and wash any undissolved residue with a few mLof water.Render the filtrate alkaline with 6Nammonium hydroxide,extract with several small portions of chloroform,and evaporate the chloroform solution on a steam bath to dryness:the resulting residue of codeine responds to Identificationtest Aunder Codeine.

B: Afiltered solution of Tablets responds to the tests for Sulfate á191ñ.

Medium: water;500mL.

Apparatus 1: 100rpm.

Time: 45minutes.

Procedure— Determine the amount of (C18H21NO3)2·H2SO4·3H2Odissolved from UVabsorbances at the wavelength of maximum absorbance at about 284nm on filtered portions of the solution under test,suitably diluted with water,if necessary,in comparison with a Standard solution having a known concentration of USP Codeine Sulfate RSin the same Medium.

Tolerances— Not less than 75%(Q)of the labeled amount of (C18H21NO3)2·H2SO4·3H2Ois dissolved in 45minutes.

Procedure for content uniformity— Transfer 1Tablet to a 50-mLvolumetric flask.Add 20mLof 0.5Nsulfuric acid and 10mLof water,shake until the Tablet is disintegrated,and allow to stand for 16hours.Dilute with water to volume,and filter,discarding the first few mLof the filtrate.Dilute a portion of the subsequent filtrate quantitatively and stepwise,if necessary,with 0.2Nsulfuric acid to obtain a solution containing approximately 120µg of codeine sulfate (trihydrate)per mL.Concomitantly determine the absorbances of this solution and a Standard solution of USP Codeine Sulfate RSin the same medium having a known concentration of about 110µg per mL,in 1-cm cells,at the wavelength of maximum absorbance at about 284nm,with a suitable spectrophotometer,using 0.2Nsulfuric acid as the blank.Calculate the quantity,in mg,of (C18H21NO3)2·H2SO4·3H2Oin the Tablet taken by the formula: in which 750.87and 696.82are the molecular weights of codeine sulfate trihydrate and anhydrous codeine sulfate,respectively;Tis the labeled quantity,in mg,of codeine sulfate in the Tablet;Cis the concentration,in µg per mL,of USP Codeine Sulfate RSin the Standard solution;Dis the concentration,in µg per mL,of codeine sulfate in the test solution,based upon the labeled quantity per Tablet and the extent of dilution;and AUand ASare the absorbances of the test solution and the Standard solution,respectively.