A: Shake well a quantity of powdered Tablets,equivalent to about 100mg of quinine sulfate,with 100mLof dilute sulfuric acid (1in 350),and filter.An appropriate dilution of the filtrate exhibits a vivid blue fluorescence.On the addition of a few drops of hydrochloric acid the fluorescence disappears.

B: In the test for Chromatographic purity,the RFvalue of the principal spot obtained from the Test preparationcorresponds to that from the Standard preparation.

C: Shake a quantity of powdered Tablets,equivalent to about 20mg of quinine sulfate,with 10mLof dilute hydrochloric acid (1in 100),and filter:the filtrate responds to the tests for Sulfate á191ñ.

D: The retention time of the major peak in the chromatogram of the Assay preparationcorresponds to that in the chromatogram of the Standard preparation,obtained as directed in the Assay.

Medium: 0.01Nhydrochloric acid;900mL.

Apparatus 1: 100rpm.

Time: 45minutes.

Procedure— Determine the amount of (C20H24N2O2)2·H2SO4·2H2Odissolved by employing UVabsorption at the wavelength of maximum absorbance at about 248nm on filtered portions of the solution under test,suitably diluted with Dissolution Medium,in comparison with a Standard solution having a known concentration of USP Quinine Sulfate RSin the same Medium.

Tolerances— Not less than 75%(Q)of the labeled amount of (C20H24N2O2)2·H2SO4·2H2Ois dissolved in 45minutes.

Procedure for content uniformity— Proceed as directed for Procedure for content uniformityunder Uniformity of dosage unitsunder Quinine Sulfate Capsules,using 1powdered Tablet instead of the contents of 1Capsule.

Methanesulfonic acid solution,Diethylamine solution,Mobile phase,System suitability preparation ,and System suitability test—Proceed as directed in the test for Limit of dihydroquinine sulfateunder Quinine Sulfate.

Standard preparation— Transfer about 20mg of USP Quinine Sulfate RS,accurately weighed,to a 100-mLvolumetric flask,dissolve in and dilute with Mobile phaseto volume,and mix.

Assay preparation— Weigh and finely powder not less than 20Tablets.Transfer an accurately weighed portion of the powder,equivalent to about 160mg of quinine sulfate,to a 100-mLvolumetric flask,add 80mLof methanol,and shake the flask by mechanical means for 30minutes.Dilute with methanol to volume,and filter,discarding the first 10mLof the filtrate.Transfer 3.0mLof the filtrate to a 25-mLvolumetric flask,dilute with Mobile phaseto volume,and mix.

Procedure (see Chromatography á621ñ)—Inject equal volumes (about 50µL)of the Standard preparationand the Assay preparationinto a chromatograph equipped with a 235-nm detector and a 3.9-mm ×30-cm column that contains packing L1.Calculate the quantity,in mg,of the sum of quinine sulfate and dihydroquinine sulfate in the portion of Tablets taken by the formula: in which Cis the concentration,in mg per mL,of USP Quinine Sulfate RSin the Standard preparation,rb,Uand rb,Sare the peak area responses of quinine obtained from the Assay preparationand the Standard preparation,respectively,and rd,Uand rd,Sare the peak area responses of dihydroquinine obtained from the Assay preparationand the Standard preparation,respectively.