A: Transfer a portion of powdered Boluses,equivalent to about 500mg of phenylbutazone,to a 250-mLconical flask,add 100mLof solvent hexane,and heat the mixture under reflux for 15minutes.Filter the hot mixture,and allow the filtrate to cool.Separate the crystals thus formed by filtration,and dry in vacuum at 80for 30minutes:the phenylbutazone so obtained responds to Identificationtest Aunder Phenylbutazone.

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

Acetate buffer,Mobile phase,Internal standard solution,Standard preparation,and Chromatographic system— Proceed as directed in the Assayunder Phenylbutazone.

Assay preparation— Weigh and finely powder a Phenylbutazone Bolus.Transfer an accurately weighed portion of the powder,equivalent to about 500mg of phenylbutazone,to a 250-mLvolumetric flask.Transfer 10.0mLof water to the flask,and shake by mechanical means for 15minutes.Add about 120mLof acetonitrile,and sonicate until insoluble material is dispersed into fine particles.Shake by mechanical means for 20minutes,dilute with acetonitrile to volume,and mix.Transfer 7.0mLof this solution to a 50-mLvolumetric flask,add 10.0mLof Internal standard solution,dilute with acetonitrile to volume,and mix.Filter a portion of this solution through a filter having a porosity of 0.5µm or finer,discarding the first few mLof the filtrate.Use the clear filtrate as the Assay preparation.[NOTE—Use this solution within 8hours of its preparation.]

Procedure— Proceed as directed for Procedurein the Assayunder Phenylbutazone.Calculate the quantity,in mg,of C19H20N2O2in the portion of the Bolus taken by the formula: in which Cis the concentration,in mg per mL,of USP Phenylbutazone RSin the Standard preparation,and RUand RSare the ratios of the peak responses of phenylbutazone to that of the internal standard obtained from the Assay preparationand the Standard preparation,respectively.