Medium: 0.01Nhydrochloric acid;500mL.

Apparatus 2: 75rpm.

Time: 30minutes.

Mobile phase— Prepare a filtered and degassed mixture of acetonitrile and water (45:55).Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Standard solution— Transfer about 25mg of USP Fludrocortisone Acetate RS,accurately weighed,to a 1000-mLvolumetric flask.Add 50mLof acetonitrile,and sonicate for 5minutes to dissolve.Dilute with 0.01Nhydrochloric acid to volume to obtain a known concentration of fludrocortisone acetate similar to that expected in the solution under test.

Chromatographic system (see Chromatography á621ñ)—The chromatograph is equipped with a 245-nm detector and a 4.6-mm ×15-cm column that contains packing L1.The flow rate is about 2mLper minute.Chromatograph the Standard solution,and record the peak responses as directed for Procedure:the column efficiency is not less than 1000theoretical plates,the tailing factor is not more than 2.0,and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 100µL)of a filtered portion of the solution under test and the Standard solutioninto the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the quantity of C23H31FO6dissolved based on the peak responses obtained from the solution under test and the Standard solution.

Tolerances— Not less than 80%(Q)of the labeled amount of C23H31FO6is dissolved in 30minutes.

Procedure for content uniformity—

Mobile solvent— Prepare as directed in the Assay.

Internal standard solution— Prepare a solution of USP Norethindrone RSin acetonitrile having a concentration of about 10µg per mL.

Standard preparation— Dissolve a suitable quantity of USP Fludrocortisone Acetate RS,accurately weighed,in Internal standard solutionto obtain a solution having a known concentration of about 0.20mg per mL.Add 5.0mLof this solution to 10.0mLof water contained in a low-actinic 50-mLvolumetric flask.Dilute with Internal standard solutionto volume to obtain a solution having a known concentration of about 20µg of fludrocortisone acetate per mL.

Test preparation— Add 1.0mLof water to 1Tablet in a 10-mLcentrifuge tube,and mix on a vortex-type mixer for 1minute or until disintegration is complete.Add 4.0mLof Internal standard solution,mix on a vortex-type mixer for 1minute,then shake by mechanical means for not less than 40minutes.Centrifuge at 3600rpm for 20minutes,or until a clear supernatant is obtained.Use the clear supernatant.

Procedure— Proceed as directed for Procedurein the Assay.Calculate the quantity,in mg,of C23H31FO6in the Tablet taken by the formula: in which C,RU,and RSare as defined in the Assay;Tis the labeled quantity,in mg,of fludrocortisone acetate in the Tablet;and Dis the concentration,in µg per mL,of fludrocortisone acetate in the Test preparation,based on the labeled quantity per Tablet and the extent of dilution.

Mobile solvent— Prepare a suitable,degassed acetonitrile solution,40%to 45%(v/v),such that the resolution factor,R,between fludrocortisone acetate and the internal standard is not less than 2.5.

Internal standard solution— Prepare a solution of USP Norethindrone RSin acetonitrile having a concentration of about 75µg per mL.

Standard preparation— Dissolve a suitable quantity of USP Fludrocortisone Acetate RS,accurately weighed,in Internal standard solutionto obtain a solution having a known concentration of about 0.50mg per mL.Pipet 5mLof this solution into a 25-mLvolumetric flask containing 5.0mLof water.Dilute with Internal standard solutionto volume to obtain a solution having a known concentration of about 0.1mg of fludrocortisone acetate per mL.

Assay preparation— Weigh and finely powder not fewer than 35Tablets.Transfer an accurately weighed portion of the powder,equivalent to about 2.5mg of fludrocortisone acetate,to a low-actinic,glass-stoppered,50-mLcentrifuge tube.Add 5.0mLof water,and mix for 1minute.Add 20.0mLof Internal standard solution,mix by mechanical means for 40minutes,then centrifuge for 15minutes or until a clear supernatant is obtained.Use the clear supernatant.

Procedure— Introduce equal volumes (about 20µL)of the Assay preparationand the Standard preparationinto a high-pressure liquid chromatograph (see Chromatography á621ñ)operated at room temperature,by means of a suitable microsyringe or sampling valve,adjusting the specimen size and other operating parameters such that the peak obtained with the Standard preparationis about 0.7full scale.Typically,the apparatus is fitted with a 3.9-mm ×30-cm stainless steel column packed with packing L1,and equipped with an UVdetector capable of monitoring absorption at 254nm and a suitable recorder.In a suitable chromatogram,the coefficient of variation for five replicate injections of the Standard preparationis not more than 3.0%and the resolution factor,R,is not less than 2.5between the two peaks.Measure the height of the peaks,at identical retention times,obtained with the Assay preparationand the Standard preparation,and calculate the quantity,in mg,of fludrocortisone acetate (C23H31FO6)in the portion of Tablets taken by the formula: in which Cis the concentration,in mg per mL,of USP Fludrocortisone Acetate RSin the Standard preparation;and RUand RSare the ratios of the peak heights of the fludrocortisone acetate peak to the internal standard peak from the Assay preparationand the Standard preparation,respectively.