A: Infrared Absorption 197K.

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 solution: 10 mg per mL, in dehydrated alcohol.

Cation suppressor regeneration solution: 0.02 M tetrabutylammonium hydroxide.

Mobile phase— Mix 1500 mL of filtered water, 250 mL of filtered methanol, 45 mL of filtered tetrahydrofuran, and 1 mL of hydrochloric acid in a 2000-mL volumetric flask. Leave at room temperature for few minutes, and dilute with water to volume. Mix, and degas. [NOTE—Avoid evaporation of tetrahydrofuran during degassing.]

Standard solution— Dissolve an accurately weighed quantity of USP Vecuronium Bromide RS, USP Pancuronium Bromide RS, USP Vecuronium Bromide Related Compound A RS, USP Vecuronium Bromide Related Compound B RS, USP Vecuronium Bromide Related Compound C RS, and USP Vecuronium Bromide Related Compound F RS in 0.0025 N hydrochloric acid, and dilute quantitatively and stepwise if necessary, to obtain a solution having a known concentration of about 0.005 mg of each compound per mL.

Test solution— Transfer about 25 mg of Vecuronium Bromide, accurately weighed, to a 25-mL volumetric flask. Add 0.5 mL of acetonitrile, dilute with 0.0025 N hydrochloric acid to volume, and mix.

Chromatographic system (see Chromatography 621)— The liquid-ion chromatograph is equipped with a conductivity detector, a 4-mm cation suppressor and a 4.6-mm × 25-cm column that contains packing L1. The flow rate is about 1.5 mL per minute. The flow rate for the cation suppressor is about 2 mL per minute. Chromatograph the Standard solution, and record the peak responses as directed for Procedure: the relative retention times are given in Table 1; the ratio of the height of the vecuronium bromide related compound F peak to the height of the valley between the vecuronium bromide related compound F peak and the pancuronium bromide peak is not less than 2.0; and the relative standard deviation for replicate injections is not more than 10.0% for each compound. [Note—The system may need equilibration for 4 hours.]

Procedure— Separately inject equal volumes (about 25 µL) of the Standard solution and the Test solution into the chromatograph, record the chromatograms, and measure the peak responses. Calculate the percentage of each vecuronium bromide related compound in the portion of Vecuronium Bromide taken by the formula: in which C is the concentration, in mg per mL, of the relevant USP Reference Standard in the Standard solution; W is the weight, in mg, of Vecuronium Bromide taken to prepare the Test solution; and rU and rS are the peak areas for the correspondent vecuronium bromide related compound obtained from the Test solution and Standard solution, respectively: the limits of impurities are specified in Table 1. [NOTE—Use the peak area of vecuronium bromide in the Standard solution as rS to calculate any unknown impurity.]

(Official January 1, 2007)

Solution A— Transfer 8.0 g of sodium perchlorate to a 1000-mL volumetric flask, dissolve in 6.0 mL of water, dilute with acetonitrile to volume, mix, filter, and degas.

Solution B— Transfer 3.2 g of ammonium chloride to a 2000-mL volumetric flask, dissolve in 16 mL of ammonium hydroxide, dilute with methanol to volume, mix, filter, and degas. [NOTE—Avoid excessive degassing to prevent the loss of ammonium hydroxide.].

Mobile phase— Prepare a mixture of Solution A and Solution B (3:2). Make adjustments if necessary (see System Suitability under Chromatography 621).

Diluent— Pipet 1.0 mL of 1 N hydrochloric acid into a 1000-mL volumetric flask, dilute with acetonitrile to volume, and mix.

Standard preparation— Dissolve an accurately weighed quantity of USP Vecuronium Bromide RS in Diluent to obtain a solution having a known concentration of about 0.5 mg per mL.

Assay preparation— Transfer about 50 mg of Vecuronium Bromide, accurately weighed, to a 100-mL volumetric flask, dissolve in and dilute with Diluent, and mix.

Chromatographic system (see Chromatography 621)— The liquid chromatograph is equipped with a 215-nm detector and a 4.6-mm × 25-cm column that contains 5-µm packing L3. The flow rate is about 0.5 mL per minute. The column temperature is maintained at 40. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the column efficiency is not less than 5000 theoretical plates; and the relative standard deviation for replicate injections 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. Calculate the quantity, in mg, of C34H57BrN2O4 in the portion of Vecuronium Bromide taken by the formula: in which C is the concentration, in mg per mL, of USP Vecuronium Bromide RS in the Standard preparation; and rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.