A: Prepare a test solution by diluting a suitable volume of Ophthalmic Solution with water, if necessary, to obtain a solution containing about 1 mg of carteolol hydrochloride per mL. Separately apply 10 µL of the test solution and 10 µL of a Standard solution of USP Carteolol Hydrochloride RS in water containing about 1 mg per mL 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 the Standard solution.

B: The retention time of the carteolol peak in the chromatogram of the Assay preparation obtained as directed in the Assay corresponds to that in the chromatogram of the Standard preparation, as obtained in the Assay.

(Official January 1, 2007)

pH 6.0 buffer, Mobile phase, Diluent, Standard preparation, Resolution solution, and Chromatographic system— Proceed as directed in the Assay under Carteolol Hydrochloride.

Assay preparation— Transfer an accurately measured volume of Ophthalmic Solution, equivalent to about 10 mg of carteolol hydrochloride, to a 100-mL volumetric flask, dilute with Diluent to volume, and mix. Pass a portion of this solution through a filter having a porosity of 0.5 µm or finer, discarding the first 2 mL of the filtrate, and use the filtrate as the Assay preparation.

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 each mL of the Ophthalmic Solution taken by the formula: in which C is the concentration, in mg per mL, of USP Carteolol Hydrochloride RS in the Standard preparation; V is the volume, in mL, of Ophthalmic Solution taken; and rU and rS are the carteolol peak responses obtained from the Assay preparation and the Standard preparation, respectively.