A: Infrared Absorption 197M.

B: Ultraviolet Absorption 197U—

Solution : 100 µg per mL.

Medium: water.

C: To a solution of about 50 mg in 3 mL of water add 1 mL of 6 N ammonium hydroxide, filter, and acidify the filtrate with nitric acid: the filtrate responds to the tests for Chloride 191.

(Official January 1, 2007)

Mobile phase— Prepare a suitable degassed solution of water, methanol, 1 M sodium acetate, and glacial acetic acid (46:40:10:4).

Standard preparation— Prepare a solution in Mobile phase of USP Oxymetazoline Hydrochloride RS having a known concentration of about 0.5 mg per mL.

Assay preparation— Transfer about 25 mg of Oxymetazoline Hydrochloride, accurately weighed, to a 50-mL volumetric flask, dissolve in Mobile phase, dilute with Mobile phase to volume, and mix.

Chromatographic system (see Chromatography 621)—The liquid chromatograph is equipped with a 280-nm detector and a 4.6-mm × 0.25-m column that contains packing L9. The flow rate is about 1 mL per minute. Chromatograph five replicate injections of the Standard preparation, and record the peak responses as directed for Procedure: the tailing factor is not more than 2.0 and the relative standard deviation 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 response for the major peak. Calculate the quantity, in mg, of C16H24N2O·HCl in the portion of Oxymetazoline Hydrochloride taken by the formula: in which C is the concentration, in mg per mL, of USP Oxymetazoline RS in the Standard preparation, and rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.