A: A 10-g portion dissolves, with effervescence, in 200 mL of water when performed as directed for the Assay preparation in the Assay.

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

C: Triturate about 0.4 g of the powder with 25 mL of methanol, and filter: this test solution responds to the Thin-layer Chromatographic Identification Test 201, a solvent system consisting of a mixture of methylene chloride and methanol (4:1) being used.

for solid packaged in multiple-unit containers: meets the requirements.

for solid packaged in single-unit containers: meets the requirements.

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

Assay preparation— Dissolve about 10 g of Acetaminophen for Effervescent Oral Solution, accurately weighed, in about 200 mL of water in a 1000-mL volumetric flask, using gentle heat if necessary, until effervescence subsides, then dilute with water to volume, and mix. Transfer 10.0 mL of this solution to a 100-mL volumetric flask, dilute with water to volume, and mix. Transfer 8.0 mL of this solution to a 50-mL volumetric flask, dilute with Mobile phase to volume, and mix. Pass a portion of this solution through a filter having a 0.5-µm or finer porosity, discarding the first 10 mL of the filtrate. Use the clear filtrate as the Assay preparation.

Procedure— Proceed as directed for Procedure in the Assay under Acetaminophen Capsules. Calculate the quantity, in g, of acetaminophen (C8H9NO2) in the portion of Acetaminophen for Effervescent Oral Solution taken by the formula: in which C is the concentration, in mg per mL, of USP Acetaminophen RS in the Standard preparation; and rU and rS are the acetaminophen peak responses obtained from the Assay preparation and the Standard preparation, respectively.