Change to read:

FOR ORAL SUSPENSION PACKAGED IN SINGLE-UNIT CONTAINERS: meets the requirements.

FOR ORAL SUSPENSION PACKAGED IN MULTIPLE-UNIT CONTAINERS: meets the requirements.

Add the following:

Diluent— Prepare a mixture of water, methanol, and formic acid (425:75:2).

Mobile phase— Prepare a filtered and degassed mixture of 0.01 M sodium butanesulfonate in Diluent. Make adjustments if necessary (see System Suitability under Chromatography 621 ).

Standard solution— Dissolve an accurately weighed quantity of USP 4-Aminophenol RS, and dilute quantitatively, and stepwise if necessary, with Mobile phase to obtain a solution having a known concentration of about 24 µg per mL.

Test solution— Transfer an accurately measured portion of Oral Suspension, equivalent to about 120 mg of acetaminophen, to a 25-mL volumetric flask, dissolve in and dilute with Mobile phase to volume, and mix.

Chromatographic system (see Chromatography 621)— The liquid chromatograph is equipped with a 272-nm detector and a 4.6-mm × 20-cm column that contains 10-µm packing L1. The flow rate is about 2.0 mL per minute. Chromatograph the Standard solution and the Test solution, and record the peak areas as directed for Procedure.

Procedure— Separately inject equal volumes (about 20 µL) of the Standard solution and the Test solution into the chromatograph, record the chromatograms, and measure the areas for the major peaks: the peak area of 4-aminophenol obtained from the Test solution is not greater than the corresponding peak area obtained from the Standard solution.USP29

(Official January 1, 2007)

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

Assay preparation— Transfer an accurately measured volume of Oral Suspension, previously well-shaken, equivalent to about 100 mg of acetaminophen, to a 200-mL volumetric flask, add about 100 mL of Mobile phase, and shake by mechanical means for 10 minutes. Dilute with Mobile phase to volume, and mix. Transfer 5.0 mL of this solution to a 250-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 mg, of acetaminophen (C8H9NO2) in each mL of the Oral Suspension taken by the formula: in which C is the concentration, in mg per mL, of USP Acetaminophen RS in the Standard preparation; V is the volume, in mL, of Oral Suspension taken; and rU and rS are the acetaminophen peak responses obtained from the Assay preparation and the Standard preparation, respectively.