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: Dilute a portion of Oral Solution with methanol to obtain a solution containing about 1mg of acetaminophen per mL.This 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.

Add the following:

for oral solution packaged in single-unit containers: meets the requirements.USP28

Add the following:

for oral solution packaged in multiple-unit containers: meets the requirements.USP28

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

Assay preparation— Transfer an accurately measured volume of Oral Solution,equivalent to about 500mg of acetaminophen,to a 250-mLvolumetric flask,dilute with Mobile phaseto volume,and mix.Transfer 5.0mLof this solution to a second 250-mLvolumetric flask,dilute with Mobile phaseto volume,and mix.Transfer 25.0mLof this solution to a 100-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 each mLof the Oral Solution taken by the formula: in which Cis the concentration,in mg per mL,of USP Acetaminophen RSin the Standard preparation;Vis the volume,in mL,of Oral Solution taken;and rUand rSare the acetaminophen peak responses obtained from the Assay preparationand the Standard preparation,respectively.