A: Thin-Layer Chromatographic Identification Test 201—

B: The retention time of the major peak in the chromatogram of the Assay preparation corresponds to that in the chromatogram of the Standard preparation, as obtained in the Assay.

test 1—

Medium: water, 500 mL.

Apparatus 2: 50 rpm.

Time: 30 minutes.

Tetrabutylammonium bromide solution, Mobile phase, System suitability solution, and Chromatographic system— Proceed as directed in the Assay under Benazepril Hydrochloride.

Procedure— Inject about 60 µL, or an amount of a filtered portion of the solution under test, equivalent to about 1.2 µg of benazepril, into the chromatograph. The amount of benazepril injected should not exceed 1.5 µg. Record the chromatogram, and measure the responses for the major peaks. Determine the quantity, in mg, of C24H28N2O5·HCl dissolved in comparison with a Standard solution having a known concentration of USP Benazepril Hydrochloride RS in the same Medium and similarly chromatographed.

Tolerances— Not less than 80% (Q) of the labeled amount of C24H28N2O5·HCl is dissolved in 30 minutes.

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

procedure for content uniformity—

Tetrabutylammonium bromide solution, Mobile phase, System suitability solution, and Chromatographic system— Proceed as directed in the Assay.

Standard solution— Dissolve an accurately weighed quantity of USP Benazepril Related Compound C RS in Mobile phase, and dilute quantitatively, and stepwise if necessary, to obtain a solution having a known concentration of about 0.006 mg per mL.

Test solution— Use the Assay preparation.

Procedure— Separately inject equal volumes (about 80 µL) of the Standard solution and the Test solution into the chromatograph, record the chromatograms, and measure the responses of the peaks for benazepril related compound C. Calculate the percentage of benazepril related compound C in the portion of Tablets taken by the formula: in which CS is the concentration, in mg per mL, of USP Benazepril Related Compound C RS in the Standard solution; CT is the concentration, in mg per mL, of benazepril hydrochloride in the Test solution; and rU and rS are the peak responses for benazepril related compound C obtained from the Test solution and the Standard solution, respectively: not more than 3.0% of benazepril related compound C is found. Calculate the percentage of each impurity (other than benazepril related compound C) in the portion of Tablets taken by the formula: in which ri is the peak response for each impurity obtained from the Test solution; and rs is the sum of the responses of all the peaks (including benazepril related compound C): not more than 1.0% of any individual impurity is found; and not more than 2.0% of total impurities is found, the results for all impurities (excluding benazepril related compound C) being added.

Tetrabutylammonium bromide solution, Mobile phase, System suitability solution, Standard preparation, and Chromatographic system— Proceed as directed in the Assay under Benazepril Hydrochloride.

Assay preparation— Finely powder not fewer than 20 Tablets, and transfer an accurately weighed portion of the powder, equivalent to about 50 mg of benazepril hydrochloride, to a 250-mL volumetric flask. Add about 150 mL of Mobile phase, and shake by mechanical means for 30 minutes. Dilute with Mobile phase to volume, mix, and centrifuge. Pass an aliquot of the supernatant through a suitable filter, discarding the first 6 mL of the filtrate.

Procedure— Separately inject equal volumes (about 25 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the areas for all the peaks. Calculate the quantity, in mg, of benazepril hydrochloride (C24H28N2 O5·HCl) in the portion of Tablets taken by the formula: in which C is the concentration, in mg per mL, of USP Benazepril Hydrochloride RS in the Standard preparation; and rU and rS are the benazepril hydrochloride peak responses obtained from the Assay preparation and the Standard preparation, respectively.