A: Infrared Absorption 197K.

B: Ultraviolet Absorption 197U—

Solution: 20 µg per mL.

C: A solution (1 in 100) responds to the tests for Chloride 191.

Test solution: methanol.

Standard solution: methanol.

Eluant: a mixture of methanol, glacial acetic acid, and water (8:1:1).

Visualization: 2.

Buffer— In a 1000-mL volumetric flask, dissolve 3.0 g of monobasic potassium phosphate, accurately weighed, in 800 mL of water. Add 3.0 mL of triethylamine, adjust with phosphoric acid to a pH of 3.0, dilute with water to volume, and mix.

Mobile phase— Prepare a filterd and degassed solution of Buffer and acetonitrile (80:20). Make adjustments if necessary (see System Suitability under Chromatography 621).

Standard preparation— Dissolve an accurately weighed quantity of USP Naphazoline Hydrochloride RS in water, and dilute quantitatively, and stepwise if necessary, to obtain a concentration of 0.05 mg per mL.

Assay preparation— Transfer about 200 mg of Naphazoline Hydrochloride, accurately weighed, to a 200-mL volumetric flask, and dissolve in and dilute with water to volume. Transfer 5.0 mL of this solution to a 100-mL volumetric flask, dilute with water to volume, and mix.

Chromatographic system ( see Chromatography 621)— The liquid chromatograph is equipped with a 280-nm detector and a 4.0-mm × 25-cm column that contains packing L1. The flow rate is about 1.5 mL per minute. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the capacity factor, k¢, is not less than 2.0; the column efficiency is not less than 1500 theoretical plates; the tailing factor is not more than 2.0; and the relative standard deviation for replicate injections of the Standard preparation 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 C14H14N2·HCl in the portion of Naphazoline Hydrochloride taken by the formula: in which C is the concentration, in mg per mL, of USP Naphazoline Hydrochloride RS in the Standard preparation; and rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.