Diluent, Mobile phase, System suitability solution, and Chromatographic system— Prepare as directed in the Assay.

2-Hydroxypropyltrimethyl ammonium chloride solution— Transfer 50.0 mg of bethanechol chloride into a 50-mL volumetric flask. Add about 40 mL of 0.1 N sodium hydroxide, and sonicate until fully dissolved. Dilute with 0.1 N sodium hydroxide to volume, and allow to stand for five days to allow adequate time for conversion from bethanechol to 2-hydroxypropyltrimethyl ammonium chloride. Chromatograph as directed for Procedure to verify the presence and location of the peak for 2-hydroxypropyltrimethyl ammonium chloride.

Standard solution— Use the Standard preparation, prepared as directed in the Assay.

Test solution— Use the Assay preparation.

Procedure— Separately inject equal volumes (about 50 µL) of the 2-Hydroxypropyltrimethyl ammonium chloride solution, the Standard solution, and the Test solution into the chromatograph, record the chromatograms, and measure the responses for the bethanechol and 2-hydroxypropyltrimethyl ammonium chloride peaks. Calculate the percentage of 2-hydroxypropyltrimethyl ammonium chloride in each mL of the Injection taken by the formula: in which CS is the concentration, in mg per mL, of USP Bethanechol Chloride RS in the Standard solution; Ci is the concentration, in mg per mL, of bethanechol chloride in the Test solution; ri is the peak response for 2-hydroxypropyltrimethyl ammonium chloride obtained from the Test solution; and rS is the peak response for bethanechol obtained from the Standard solution. Not more than 4.0% is found.

(Official January 1, 2007)

Diluent— Transfer 10 mg of calcium chloride and 10 mg of magnesium chloride to a 100-mL volumetric flask, dissolve in and dilute with water to volume, and mix.

Mobile phase— Prepare a filtered and degassed solution of 20 mM methanesulfonic acid. Make adjustments if necessary (see System Suitability under Chromatography 621).

System suitability solution— Transfer 25 mg of USP Bethanechol Chloride RS, accurately weighed, to a 25-mL volumetric flask, and add 15 mL of water, 2.0 mL of the Diluent, and 0.5 mL of 0.1 N sodium hydroxide. Dilute with water to volume, and mix.

Standard preparation— Dissolve an accurately weighed quantity of USP Bethanechol Chloride RS in water, and dilute quantitatively, and stepwise if necessary, with water to obtain a solution having a known concentration of about 1.0 mg per mL.

Assay preparation— Dilute an accurately measured volume of Injection, if necessary, with water to obtain a solution having a concentration of about 1.0 mg per mL.

Chromatographic system (see Chromatography 621)— The liquid chromatograph is equipped with a conductivity detector and a 4-mm × 25-cm column that contains packing L53. The flow rate is about 1 mL per minute. Chromatograph the System suitability solution, and record the peak responses as directed for Procedure: the relative retention times are 1.0 for sodium, 1.4 for magnesium, 1.6 for calcium, 2.0 for 2-hydroxypropyltrimethyl ammonium chloride, and 2.8 for bethanechol; the resolution, R, between the calcium ion and 2-hydroxypropyltrimethyl ammonium chloride is not less than 2.0; the column efficiency determined from the bethanechol peak is not less than 350 theoretical plates; the tailing factor is not more than 4.5; and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 50 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 bethanechol chloride (C7H17ClN2O2) in each mL of the Injection taken by the formula: in which C is the concentration, in mg per mL, of USP Bethanechol Chloride RS in the Standard preparation; and rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.