A: Infrared Absorption 197K.

B: It responds to the tests for Chloride 191.

Phosphate buffer— Transfer 6.8 mL of phosphoric acid to a 2000-mL volumetric flask, add about 1900 mL of water, and mix. Adjust with sodium hydroxide solution (1 in 2) to a pH of 3.0, dilute with water to volume, and mix.

Mobile phase— Prepare a filtered and degassed mixture of acetonitrile, Phosphate buffer, and methanol (56:40:4). Make adjustments if necessary (see System Suitability under Chromatography 621).

System suitability solution— Prepare a solution in Mobile phase containing about 0.8 mg of USP Apraclonidine Hydrochloride RS per mL.

Test solution— Transfer about 20 mg of Apraclonidine Hydrochloride, accurately weighed, to a 25-mL volumetric flask, dissolve in and dilute with Mobile phase to volume, and mix.

Chromatographic system (see Chromatography 621)—The liquid chromatograph is equipped with a 220-nm detector and an 8-mm × 100-mm column that contains packing L7. The flow rate is about 3 mL per minute. Chromatograph the System suitability solution, and record the peak responses as directed for Procedure: the tailing factor for the apraclonidine peak is not more than 2.2, and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Inject about 20 µL of the Test solution into the chromatograph, record the chromatogram, and measure the areas for the major peaks. [NOTE—Allow about five times the elution time of apraclonidine before making the next injection.] Calculate the percentage of each peak, other than the solvent peak and the apraclonidine peak, in the specimen of Apraclonidine Hydrochloride taken by the same formula: in which ri is the response of each peak other than the principal peak, and rt is the sum of the responses of all of the peaks, excluding that of the solvent peak: not more than 1.0% for any individual impurity and not more than 2.0% total impurities are found.

(Official January 1, 2007)