Naphazoline Hydrochloride
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C14H14N2·HCl 246.74

1H-Imidazole, 4,5-dihydro-2-(1-naphthalenylmethyl)-, monohydrochloride.
2-(1-Naphthylmethyl)-2-imidazoline monohydrochloride [550-99-2].
» Naphazoline Hydrochloride contains not less than 98.0 percent and not more than 102.0 percent of C14H14N2·HCl, calculated on the dried basis.
Packaging and storage— Preserve in tight, light-resistant containers.
Solution: 20 µg per mL.
Medium: methanol.
Absorptivities at 280 nm, calculated on the dried basis, do not differ by more than 3.0%.
C: A solution (1 in 100) responds to the tests for Chloride 191.
pH 791: between 5.0 and 6.6, in a 1 in 100 solution in carbon dioxide-free water, and the solution is clear and colorless.
Loss on drying 731 Dry it at 105 for 2 hours: it loses not more than 0.5% of its weight.
Residue on ignition 281: not more than 0.2%.
Ordinary impurities 466
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:
4000C(rU / rS)
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.
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Feiwen Mao, M.S.
(MDOOD05) Monograph Development-Ophthalmics Oncologics and Dermatologicals
Reference Standards Lili Wang, Technical Services Scientist
USP32–NF27 Page 3032
Pharmacopeial Forum: Volume No. 31(4) Page 1093
Chromatographic Column—
Chromatographic columns text is not derived from, and not part of, USP 32 or NF 27.