A: It meets the requirements of the flame test for Sodium á191ñ.

B: Add 2mLof 15%potassium carbonate TSto 2mLof Oral Solution,boil,and cool.Add 4mLof potassium pyroantimonate TS:a dense precipitate is formed(presence of sodium).

C: To 2mLof a dilution of Oral Solution (1in 20)add 5mLof sodium cobaltinitrite TS:a yellow precipitate is not formed immediately(absence of potassium).

D: It meets the requirements of the tests for Citrate á191ñ,3to 5drops of Oral Solution and 20mLof the mixture of pyridine and acetic anhydride being used.

FOR ORAL SOLUTION PACKAGED IN SINGLE-UNIT CONTAINERS: meets the requirements.

FOR ORAL SOLUTION PACKAGED IN MULTIPLE-UNIT CONTAINERS: meets the requirements.

Potassium stock solution,Sodium stock solution,Lithium diluent solution,andStandard preparation— Prepare as directed in the Assay for sodium and potassiumunder Tricitrates Oral Solution.

Assay preparation— Transfer an accurately measured volume of Oral Solution,equivalent to about 1g of sodium citrate dihydrate,to a 100-mLvolumetric flask,dilute with water to volume,and mix.Transfer 50µLof this solution to a 10-mLvolumetric flask,dilute with Lithium diluent solutionto volume,and mix.

Procedure— Using a suitable flame photometer,adjusted to read zero with Lithium diluent solution,concomitantly determine the sodium flame emission readings for the Standard preparationand the Assay preparationat the wavelength of maximum emission at about 589nm.Calculate the quantity,in g,of Na in each mLof Oral Solution taken by the formula: in which 14.61is the weight,in g,of sodium chloride in the Sodium stock solution;Vis the volume,in mL,of Oral Solution taken,22.99is the atomic weight of sodium;58.44is the molecular weight of sodium chloride;and RU,Naand RS,Naare the sodium emission readings obtained for the Assay preparationand the Standard preparation,respectively.

Cation-exchange column— Mix 10g of styrene-divinylbenzene cation-exchange resin with 50mLof water in a suitable beaker.Allow the resin to settle,and decant the supernatant until a slurry of resin remains.Pour the slurry into a 15-mm ×30-cm glass chromatographic tube (having a sealed-in,coarse-porosity fritted disk and fitted with a stopcock),and allow to settle as a homogeneous bed.Wash the resin bed with about 100mLof water,closing the stopcock when the water level is about 2mm above the resin bed.

Procedure— Transfer an accurately measured volume of Oral Solution,equivalent to about 1g of sodium citrate dihydrate,to a 100-mLvolumetric flask;dilute with water to volume;and mix.Pipet 5mLof this solution carefully onto the top of the resin bed in the Cation-exchange column.Place a 250-mLconical flask below the column,open the stopcock,and allow to flow until the solution has entered the resin bed.Elute the column with 60mLof water at a flow rate of about 5mLper minute,collecting about 65mLof the eluate.Add 5drops of phenolphthalein TSto the eluate,swirl the flask,and titrate with 0.02Nsodium hydroxide VS.Record the buret reading,and calculate the volume(B)of 0.02Nsodium hydroxide consumed.Calculate the quantity,in mg,of sodium citrate dihydrate (C6H5Na3O7·2H2O)in each mLof the Oral Solution taken by the formula: in which 1.961is the equivalent,in mg,of C6H5Na3O7·2H2O,of each mLof 0.02Nsodium hydroxide;Vis the volume,in mL,of Oral Solution taken;294.10and 210.14are the molecular weights of sodium citrate dihydrate and citric acid monohydrate,respectively;and Cis the concentration,in mg per mL,of citric acid monohydrate in the Oral Suspension,as obtained in the Assay for citric acid.

1.401A(20/V),