A: Transfer a volume of Oral Solution,equivalent to about 100mg of saccharin,to a small dish,evaporate to dryness,and gently fuse the residue over a small flame until it no longer evolves ammonia.Allow the residue to cool,dissolve in 20mLof water,neutralize the solution with 3Nhydrochloric acid,and filter:the addition of 1drop of ferric chloride TSto the filtrate produces a violet color.

B: It responds to the tests for Sodium á191ñ.

Mobile phase— Mix 5mLof 10percent tetramethylammonium hydroxide solution and 400mLof water in a 500-mLvolumetric flask,adjust with phosphoric acid to a pHof 4.0,and mix.Add 50mLof methanol to the solution,dilute with water to volume,mix,and degas the solution.

Standard preparation— Add to an accurately weighed quantity of USP Saccharin RSan amount of 0.1Nsodium hydroxide sufficient to dissolve the solid,and dilute quantitatively with water to obtain a solution having a known concentration of about 1.2mg of saccharin per mL.

Assay preparation— Transfer an accurately measured volume of Oral Solution,equivalent to about 120mg of saccharin,to a 100-mLvolumetric flask,dilute with water to volume,and mix.

Chromatographic system (see Chromatography á621ñ)—The liquid chromatograph is equipped with a 257-nm detector and a 4.6-mm ×25-cm column that contains packing L1.The flow rate is about 2mLper minute.Chromatograph three replicate injections of the Standard preparation,and record the peak responses as directed for Procedure:the relative standard deviation is not more than 2.0%.

Procedure— Separately inject equal volumes (about 10µL)of the Standard preparationand the Assay preparationinto the chromatograph using a suitable microsyringe or sampling valve,record the chromatograms,and measure the responses for the major peaks.Calculate the quantity,in mg,of saccharin (C7H5NO3S)in each mLof the Oral Solution taken by the formula: in which Cis the concentration,in mg per mL,of USP Saccharin RSin the Standard preparation,Vis the volume,in mL,of Oral Solution taken,and rUand rSare the peak responses obtained from the Assay preparationand the Standard preparation,respectively.