A: Infrared Absorption á197Kñ.

B: 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.

Solution A,Solution B,and Mobile phase— Proceed as directed in the Assay.

System suitability solution— Dissolve accurately weighed quantities of USP Nabumetone RSand USP Nabumetone Related Compound A RSin acetonitrile to obtain a solution having known concentrations of about 1mg per mLand 1µg per mL,respectively.

Test solution— Use the Assay preparation.

Chromatographic system (see Chromatography á621ñ)— Proceed as directed in the Assay,except to chromatograph the System suitability solution,and record the peak responses as directed for Procedure:the relative retention times are about 0.9for nabumetone related compound Aand 1.0for nabumetone;the resolution,R,between nabumetone related compound Aand nabumetone is not less than 1.5;the column efficiency is not less than 3600theoretical plates;the tailing factor determined from the nabumetone peak is between 0.8and 2.0;and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Inject 10µLof theTest solutioninto the chromatograph,record the chromatogram,and measure all of the peak areas.Calculate the percentage of each impurity in the portion of Nabumetone taken by the formula: in which Fis the relative response factor and is equal to 0.12for any peak with a relative retention time of 0.73,0.10for any peak with a relative retention time of 2.7,0.25for any peak with a relative retention time of 0.93,0.42for any peak with a relative retention time of 1.2,0.94for any peak with a relative retention time of 0.85,1.02for any peak with a relative retention time of 1.9,and 0.91for any peak with a relative retention time of 2.6;riis the peak response for each impurity;and rNis the nabumetone peak response:not more than 0.3%of any impurity with a relative retention time of 2.7is found;not more than 0.1%of any other individual impurity is found;and not more than 0.8%of total impurities is found.

Solution A— Prepare a filtered and degassed mixture of water and glacial acetic acid (999:1).

Solution B— Prepare a filtered and degassed mixture of acetonitrile and tetrahydrofuran (7:3).

Mobile phase— Use variable mixtures of Solution Aand Solution Bas directed for Chromatographic system.Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Standard preparation— Dissolve an accurately weighed quantity of USP Nabumetone RSin acetonitrile to obtain a solution having a known concentration of about 1.0mg per mL.

Assay preparation— Transfer about 100mg of Nabumetone,accurately weighed,to a 100-mLvolumetric flask,dissolve in and dilute with acetonitrile to volume,and mix.

Chromatographic system (see Chromatography á621ñ)— The liquid chromatograph is equipped with a 254-nm detector and a 4.6-mm ×15-cm column that contains 4-µm packing L1.The flow rate is about 1.3mLper minute.The chromatograph is programmed as follows. Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 10µL)of the Standard preparationand the Assay preparationinto the chromatograph,record the chromatograms,and measure the responses for the nabumetone peaks.Calculate the quantity,in mg,of C15H16O2in the portion of Nabumetone taken by the formula: in which Cis the concentration,in mg per mL,of USP Nabumetone RSin the Standard preparation;and rUand rSare the peak responses obtained from the Assay preparationand the Standard preparation,respectively.