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.

Mobile phase and Chromatographic system— Proceed as directed in the Assay.

Test solution— Transfer about 38 mg of Betahistine Hydrochloride, accurately weighed, to a 100-mL volumetric flask, dissolve in and dilute with Mobile phase to volume, and mix.

Procedure— Inject about 10 µL of the Test solution into the chromatograph, record the chromatogram, and measure the peak responses. Calculate the percentage of each impurity in the portion of Betahistine Hydrochloride taken by the formula: in which F is the response factor of the respective impurity (see Table 1) and 1.0 for all other peaks; ri is the peak response for each impurity; and rs is the sum of the responses of all of the peaks, adjusted for the relative response factor. In addition to not exceeding the limits for impurities in Table 1, not more than 0.1% of any other individual impurity is found; and not more than 0.5 % of total impurities is found.

(Official January 1, 2007)

Ammonium acetate buffer— Dissolve about 0.69 g of ammonium acetate in 1000 mL of water. Adjust with glacial acetic acid to a pH of 4.7.

Mobile phase— Prepare a filtered and degassed mixture of 350 mL of acetonitrile and 650 mL of Ammonium acetate buffer, containing 2.88 g of sodium lauryl sulfate. Make adjustments if necessary (see System Suitability under Chromatography 621).

Standard preparation— Dissolve an accurately weighed quantity of USP Betahistine Hydrochloride RS in Mobile phase to obtain a solution having a known concentration of about 0.38 mg per mL.

Assay preparation— Transfer about 38 mg of Betahistine Hydrochloride, accurately weighed, to a 100-mL volumetric flask, dissolve in and dilute with Mobile phase to volume, and mix.

Chromatographic system (see Chromatography 621)— The liquid chromatograph is equipped with a 254-nm detector and 3.0-mm × 15-cm column that contains packing L1. The column temperature is maintained at 40. The flow rate is about 0.5 mL per minute. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the column efficiency is not less than 5000 theoretical plates; the tailing factor for the betahistine peak is not more than 2.0; and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 10 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 C8H12N2·2HCl in the portion of Betahistine Hydrochloride taken by the formula: in which C is the concentration, in mg per mL, of USP Betahistine Hydrochloride RS in the Standard preparation; and rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.