Packaging and storage—
Preserve in tight, light-resistant containers. Store at 25
, excursions permitted between 15
and 30
.
Identification—
B:
The retention time of the major peak for verapamil in the chromatogram of the Test preparation corresponds to that exhibited in the chromatogram of Standard preparation B, as obtained in the test for Chromatographic purity.
C:
It responds to the tests for
Chloride 
191
.
pH 791:
between 4.5 and 6.5, in a solution, prepared with gentle heating, containing 50 mg per mL.
Chromatographic purity—
Aqueous solvent mixture—
Prepare a 0.015 N sodium acetate solution containing about 33 mL of glacial acetic acid per L.
Mobile phase—
Prepare a filtered and degassed mixture of
Aqueous solvent mixture, acetonitrile, and 2-aminoheptane (70:30:0.5). Make adjustments if necessary (see
System Suitability under
Chromatography 621).
Standard preparations—
Dissolve an accurately weighed quantity of
USP Verapamil Hydrochloride RS in
Mobile phase, and dilute quantitatively, and stepwise if necessary, with
Mobile phase to obtain
Standard preparation A and
Standard preparation B having known concentrations of about 5.6 and 9.4 µg per mL, respectively.
Test preparation—
Prepare a solution of Verapamil Hydrochloride in Mobile phase having a known concentration of about 1.9 mg per mL.
Chromatographic system (see Chromatography 621)—
The liquid chromatograph is equipped with a 278-nm detector and a 4.6-mm × 12.5- to 15-cm column that contains packing L1. The flow rate is about 0.9 mL per minute. Chromatograph the
System suitability solution, and record the peak responses as directed for
Procedure: the relative retention times are about 0.88 for verapamil related compound B and 1.0 for verapamil; the resolution,
R, between the verapamil related compound B and verapamil peaks is not less than 1.5, and the relative standard deviation for replicate injections is not more than 2.0%.
Procedure—
Separately inject equal volumes (about 10 µL) of Standard preparations A and B and the Test preparation into the chromatograph, and allow the Test preparation to elute for not less than four times the retention time for verapamil. Record the chromatograms, and measure all the peak responses. The sum of the peak responses, other than that of verapamil, from the Test preparation is not greater than the verapamil peak response obtained from Standard preparation B (0.5%); and no single peak response is greater than that of the verapamil peak response obtained from Standard preparation A (0.3%).
Assay—
Dissolve about 400 mg of Verapamil Hydrochloride, accurately weighed, in 40 mL of glacial acetic acid; and add 10 mL of
mercuric acetate TS and 5 mL of acetic anhydride. Titrate (see
Titrimetry 541) with 0.10 N perchloric acid VS, determining the endpoint potentiometrically. Perform a blank determination, and make any necessary correction. Each mL of 0.10 N perchloric acid is equivalent to 49.11 mg of C
27H
38N
2O
4·HCl.
;)
-[3-[[2-(3,4-dimethoxyphenyl)ethyl]methylamino]propyl]-3,4-dimethoxy-