Medium: sodium lauryl sulfate solution (2in 100);900mL.

Apparatus 2: 50rpm.

Time: 45minutes.

Procedure— Determine the amount of C15H16O2dissolved by employing UVabsorption at the wavelengths of maximum and minimum absorbance at about 270nm and 296nm,respectively,on filtered portions of the solution under test,suitably diluted with Medium,if necessary,in comparison with a Standard solution having a known concentration of USP Nabumetone RSin the same Medium.

Tolerances— Not less than 75%(Q)of the labeled amount of C15H16O2is dissolved in 45minutes.

Mobile phase— Prepare a solution of 6mLof glacial acetic acid in 350mLof water.Adjust with 1Nsodium hydroxide to a pHof 3.7,and dilute with water to obtain 400mL.Prepare a filtered and degassed mixture of acetonitrile and this solution (3:2).Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Standard preparation— Dissolve an accurately weighed quantity of USP Nabumetone RSin a mixture of methanol and water (9:1)to obtain a solution having a known concentration of about 0.5mg per mL.

Assay preparation— Weigh and finely powder not fewer than 20Tablets.Transfer an accurately weighed portion of the powder,equivalent to about 500mg of nabumetone,to a 1000-mLvolumetric flask,add about 100mLof water,and stir with the aid of a magnetic stirrer for 5minutes.Dilute with methanol to volume,stir for another 15minutes,and filter.

Chromatographic system (see Chromatography á621ñ)— The liquid chromatograph is equipped with a 280-nm detector and an 8-mm ×10-cm column that contains 10-µm packing L1.The flow rate is about 2mLper minute.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the column efficiency is not less than 1500theoretical plates;the tailing factor is not more than 1.5;and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 20µL)of the Standard preparationand the Assay preparationinto the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the quantity,in mg,of nabumetone (C15H16O2)in the portion of Tablets 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.