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

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

test 3— If the product complies with this test, the labeling indicates that the product meets USP Dissolution Test 3.

test 4— If the product complies with this test, the labeling indicates that the product meets USP Dissolution Test 4.

test 5— If the product complies with this test the labeling indicates that the product meets USP Dissolution Test 5.

test 6— If the product complies with this test, the labeling indicates that the product meets USP Dissolution Test 6.

test 8— If the product complies with this test, the labeling indicates that the product meets USP Dissolution Test 8.

Mobile phase— Prepare a suitable mixture of water, methanol, and triethylamine (140:60:1), adjust with phosphoric acid to a pH of 7.5, filter, and degas. Make adjustments if necessary (see System Suitability under Chromatography 621).

Standard preparation— Dissolve an accurately weighed quantity of USP Procainamide Hydrochloride RS in Mobile phase to obtain a solution having a known concentration of about 0.5 mg per mL (Stock standard solution). Quantitatively dilute an accurately measured volume of this solution with Mobile phase to obtain a solution having a known concentration of about 0.05 mg per mL (Standard preparation).

Assay preparation— Transfer not fewer than 10 Tablets, accurately counted, to a 1000-mL volumetric flask, and add 100 mL of a mixture of methanol and methylene chloride (1:1). Place the flask in a 40 sonicator bath, and sonicate, with occasional shaking, until the Tablets have disintegrated completely. Add about 700 mL of methanol, and sonicate for 10 minutes, with occasional shaking. Allow to cool, dilute with methanol to volume, and mix. Filter a portion of this solution, discarding the first 10 mL of the filtrate. Quantitatively dilute an accurately measured volume of the filtrate with Mobile phase to obtain a solution having a concentration of about 0.5 mg of procainamide hydrochloride per mL. Use a portion of this stock solution for the Identification test. Quantitatively dilute another accurately measured volume of the stock solution with Mobile phase to obtain a solution having a concentration of about 0.05 mg per mL (Assay preparation).

Resolution solution— Prepare a solution of p-aminobenzoic acid in Mobile phase containing 0.1 mg per mL. Pipet 10 mL of this solution and 10 mL of the Stock standard into a 100-mL volumetric flask, dilute with Mobile phase to volume, and mix.

Chromatographic system (see Chromatography 621)— The liquid chromatograph is equipped with a 280-nm detector and a 3.9-mm × 30-cm column that contains 10-µm packing L1. The flow rate is about 1 mL per minute. Chromatograph the Resolution solution: the resolution, R, is not less than 2.0. Chromatograph replicate injections of the Standard preparation: the relative standard deviation is not more than 2.0%.

Procedure— Separately inject equal volumes (about 20 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. The relative retention times are about 0.5 for p-aminobenzoic acid and 1.0 for procainamide. Calculate the quantity, in mg, of procainamide hydrochloride (C13H21N3O·HCl) per Tablet taken by the formula: in which L is the labeled quantity, in mg, of procainamide hydrochloride in each Tablet; D is the concentration, in mg per mL, of procainamide hydrochloride in the Assay preparation, based on the number of Tablets taken, the labeled quantity per Tablet, and the extent of dilution; C is the concentration, in mg per mL, of USP Procainamide Hydrochloride RS in the Standard preparation; and rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.