A: It meets the requirements under Identification—Organic Nitrogenous Bases 181, a volume of Injection equivalent to 100 mg of verapamil hydrochloride being used, chloroform being used in place of carbon disulfide, and a 0.1-mm cell being used in place of a 1-mm cell.

B: The chromatogram of the Assay preparation obtained as directed in the Assay exhibits a major peak for verapamil hydrochloride, the retention time of which corresponds to that exhibited in the chromatogram of the Standard preparation, obtained as directed in the Assay.

C: It responds to the tests for Chloride 191.

Aqueous solvent mixture , Mobile phase, System suitability solution, and Chromatographic system—Proceed as directed for Chromatographic purity under Verapamil Hydrochloride.

Standard solution— Dissolve accurately weighed quantities of USP Verapamil Hydrochloride RS, USP Verapamil Related Compound A RS, 3,4-dimethoxybenzaldehyde, and 3,4-dimethoxybenzyl alcohol in Mobile phase to obtain a solution having known concentrations of about 2.5 mg of USP Verapamil Hydrochloride RS per mL and 0.0075 mg each of USP Verapamil Related Compound A RS, 3,4-dimethoxybenzaldehyde, and 3,4-dimethoxybenzyl alcohol per mL.

Test solution— Use the Assay preparation.

Procedure— Separately inject equal volumes (about 10 µL) of the Standard solution and the Test solution into the chromatograph, and allow the Test solution to elute for not less than four times the retention time for verapamil hydrochloride. Record the chromatograms, and measure all of the peak responses. The retention times are about 0.4 for 3,4-dimethoxybenzyl alcohol, 0.5 for verapamil related compound A, 0.7 for 3,4-dimethoxybenzaldehyde, and 1.0 for verapamil. Calculate the quantity, in mg, of each individual impurity in each mL of the Injection taken by the formula: in which C is the concentration, in mg per mL, of the appropriate impurity in the Standard solution; L is the labeled quantity, in mg per mL, of verapamil hydrochloride in the Injection; D is the concentration, in mg per mL, of verapamil hydrochloride in the Test solution, on the basis of the labeled quantity in each mL and the extent of dilution; and rU and rS are the peak responses of the appropriate impurity in the Test solution and the Standard solution, respectively: not more than 0.3% of any specified impurity is found, and the sum of all impurities is not greater than 1.0%.

(Official January 1, 2007)

Aqueous solvent mixture , Mobile phase, System suitability solution, and Chromatographic system—Proceed as directed for Chromatographic purity under Verapamil Hydrochloride.

Standard preparation— Dissolve accurately weighed quantities of USP Verapamil Hydrochloride RS in Mobile phase to obtain a solution having a known concentration of about 2.5 mg per mL.

Assay preparation— Dilute the Injection quantitatively, if necessary, with Mobile phase to obtain a solution having a concentration of not more than 2.5 mg of verapamil hydrochloride per mL.

Procedure— Separately inject equal volumes (about 10 µL) of the Standard preparation and the Assay preparation into the chromatograph, and allow the Assay preparation to elute for not less than four times the retention time for verapamil. Record the chromatograms, and measure the responses for all of the major peaks. Calculate the quantity, in mg, of C27H38N2O4·HCl, in each mL of the Injection taken by the formula: in which C is the concentration, in mg per mL, of USP Verapamil Hydrochloride RS in the Standard preparation; L is the labeled quantity, in mg per mL, of verapamil hydrochloride in the Injection; D is the concentration, in mg per mL, of verapamil hydrochloride in the Assay preparation, on the basis of the labeled quantity in each mL and the extent of dilution; and rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.