A: Shake a quantity of powdered Tablets, equivalent to about 50 mg of quinidine sulfate, with 100 mL of dilute sulfuric acid (1 in 350), and filter: the filtrate so obtained 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 RF value of the principal spot obtained from the Test preparation corresponds to that from the Standard preparation.

C: Shake a quantity of the powdered Tablets, equivalent to about 100 mg of quinidine sulfate, with 10 mL of dilute hydrochloric acid (1 in 100), and filter: the filtrate so obtained meets the requirements of the tests for Sulfate 191.

test 1— If the product complies with this test, the labeling indicates that it meets USP Dissolution Test 1.

Medium: 0.1 N hydrochloric acid; 900 mL.

Apparatus 1: 100 rpm.

Times: 1, 4, and 12 hours.

Procedure— Using filtered portions of the solution under test, diluted with 0.1 N hydrochloric acid if necessary, determine the amount of (C20H24N2O2)2·H2SO4·2H2O dissolved from UV absorbances at the wavelength of maximum absorbance at about 248 nm by comparison with a Standard solution having a known concentration of USP Quinidine Sulfate RS in the same Medium.

Tolerances— The percentages of the labeled amount of (C20H24N2O2)2·H2SO4·2H2O dissolved at the times specified conform to Acceptance Table 2.

test 2— If the product complies with this test, the labeling indicates that it meets USP Dissolution Test 2.

Medium: 0.1 N hydrochloric acid; 900 mL.

Apparatus 1: 100 rpm.

Times: 1, 4, and 12 hours.

Procedure— Proceed as directed for Test 1.

Tolerances— The percentages of the labeled amount of (C20H24N2O2)2·H2SO4·2H2O dissolved at the times specified conform to Acceptance Table 2.

Procedure for content uniformity— Proceed as directed for Procedure for content uniformity in the test for Uniformity of dosage units under Quinidine Sulfate Capsules, using 1 powdered Tablet instead of the contents of 1 Capsule.