A: The retention time of the major peak in the chromatogram of the Assay preparationcorresponds to that in the chromatogram of the Standard preparation,as obtained in the Assay.

B: Triturate an amount of powdered Tablets,equivalent to about 50mg of acetaminophen,with 50mLof methanol,and filter:the clear filtrate (test solution)responds to the Thin-layer Chromatographic Identification Test á201ñ,a solvent system consisting of a mixture of methylene chloride and methanol (4:1)being used.

Medium: pH5.8phosphate buffer (see Buffer Solutionsin the section Reagents,Indicators,and Solutions);900mL.

Apparatus 2: 50rpm.

Time: 30minutes.

Procedure— Determine the amount of C8H9NO2dissolved by employing UVabsorption at the wavelength of maximum absorbance at about 243nm on filtered portions of the solution under test,suitably diluted with Dissolution Medium,if necessary,in comparison with a Standard solution having a known concentration of USP Acetaminophen RSin the same Medium.

Tolerances— Not less than 80%(Q)of the labeled amount of C8H9NO2is dissolved in 30minutes.

FOR TABLETS LABELED AS CHEWABLE—

Mobile phase,Standard preparation,and Chromatographic system— Proceed as directed in the Assayunder Acetaminophen Capsules.

Assay preparation— Weigh and finely powder not fewer than 20Tablets.Transfer an accurately weighed portion of the powder,equivalent to about 100mg of acetaminophen,to a 200-mLvolumetric flask,add about 100mLof Mobile phase,shake by mechanical means for 10minutes,sonicate for about 5minutes,dilute with Mobile phaseto volume,and mix.Transfer 5.0mLof this solution to a 250-mLvolumetric flask,dilute with Mobile phaseto volume,and mix.Pass a portion of this solution through a filter having a 0.5-µm or finer porosity,discarding the first 10mLof the filtrate.Use the clear filtrate as the Assay preparation.

Procedure— Proceed as directed for Procedurein the Assayunder Acetaminophen Capsules.Calculate the quantity,in mg,of acetaminophen (C8H9NO2)in the portion of Tablets taken by the formula: in which Cis the concentration,in mg per mL,of USP Acetaminophen RSin the Standard preparation;and rUand rSare the acetaminophen peak responses obtained from the Assay preparationand the Standard preparation,respectively.