A: Infrared Absorption 197K.

B: Ultraviolet Absorption 197U—

C: A solution (1 in 50) responds to the tests for Chloride 191.

Standard solution A— Prepare a solution of USP Carteolol Hydrochloride RS in methanol containing 0.5 mg per mL.

Standard solution B— Transfer 5.0 mL of Standard solution A to a 50-mL volumetric flask, dilute with methanol to volume, and mix.

Standard solution C— Transfer 5.0 mL of Standard solution B to a 10-mL volumetric flask, dilute with methanol to volume, and mix.

Test solution— Transfer 250 mg of Carteolol Hydrochloride to a 10-mL volumetric flask, dissolve in methanol, using heat or sonication if necessary to achieve dissolution, dilute with methanol to volume, and mix.

Procedure— Apply separate 10-µL portions of the Test solution and the Standard solutions to the starting line of a thin-layer chromatographic plate (see Chromatography 621) coated with a 0.25-mm layer of chromatographic silica gel mixture. Allow the spots to dry. Line a chromatographic chamber with filter paper, and saturate the paper with a solvent system consisting of a mixture of chloroform, methanol, and ammonium hydroxide (50:20:1). Place the plate in the chamber, and develop the chromatogram until the solvent front has moved about three-fourths of the length of the plate. Remove the plate from the chamber, and allow to air-dry. Examine the plate under short-wavelength UV light: the RF value of the principal spot in the chromatogram obtained from the Test solution corresponds to that in the chromatogram obtained from Standard solution A. Compare the sizes and intensities of any spots other than the principal spot in the chromatogram obtained from the Test solution with those of the principal spots in the chromatograms obtained from the Standard solutions: no spot exceeds in size or intensity the principal spot in the chromatogram obtained from Standard solution B (0.2%), and the sum of all the impurity spots does not exceed 0.5%.

pH 6.0 Buffer— Dissolve 1.34 g of dibasic sodium phosphate in about 1900 mL of water, adjust with 1 M phosphoric acid to a pH of 6.0 ± 0.05, dilute with water to 2000 mL and mix.

Mobile phase— Prepare a mixture of pH 6.0 Buffer and acetonitrile (750:250). Make adjustments if necessary (see System Suitability under Chromatography 621). [note—Increasing the proportion of pH 6.0 buffer increases resolution.]

Diluent— Prepare a mixture of pH 6.0 Buffer and methanol (1:1).

Standard preparation— Quantitatively dissolve an accurately weighed quantity of USP Carteolol Hydrochloride RS in water to obtain a solution having a known concentration of about 1 mg per mL. Transfer 10.0 mL of this stock solution to a 100-mL volumetric flask containing 5 mL of acetonitrile, dilute with water to volume, and mix. This solution contains about 0.1 mg of USP Carteolol Hydrochloride RS per mL.

Resolution solution— Transfer about 50 mg of p-acetotoluidide to a 100-mL volumetric flask, add 50 mL of acetonitrile, and swirl to dissolve. Dilute with water to volume, and mix. Transfer 10 mL of this solution and 10 mL of the stock solution used to prepare the Standard preparation to a second 100-mL volumetric flask, dilute with water to volume, and mix. Each mL of this solution contains about 0.05 mg of p-acetotoluidide and 0.1 mg of USP Carteolol Hydrochloride RS.

Assay preparation— Transfer about 100 mg of Carteolol Hydrochloride, accurately weighed, to a 100-mL volumetric flask, dissolve in and dilute with water to volume, and mix. Transfer 10.0 mL of this solution to a second 100-mL volumetric flask containing 5 mL of acetonitrile, dilute with water to volume, and mix.

Chromatographic system (see Chromatography 621)—The liquid chromatograph is equipped with a 252-nm detector and a 3.9-mm × 30-cm column that contains packing L1. The flow rate is about 1 mL per minute. Chromatograph the Resolution solution, and record the peak responses as directed under Procedure: the relative retention times are about 0.8 for carteolol and 1.0 for p-acetotoluidide; and the resolution, R, between the carteolol peak and the p-acetotoluidide peak is not less than 3. Chromatograph the Standard preparation, and record the peak responses as directed under Procedure: 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 areas for the major peaks. Calculate the quantity, in mg, of C16H24N2O3·HCl in the portion of Carteolol Hydrochloride taken by the formula: in which C is the concentration, in mg per mL, of USP Carteolol Hydrochloride RS in the Standard preparation; and rU and rS are the carteolol peak responses obtained from the Assay preparation and the Standard preparation, respectively.