(Official January 1, 2007)

Mobile phase— Prepare a filtered and degassed mixture of pH 2.5 Buffer and acetonitrile (850:150). Make adjustments if necessary (see System Suitability under Chromatography 621).

Standard preparation— Dissolve an accurately weighed quantity of USP Epinephrine Bitartrate RS in water, and dilute quantitatively, and stepwise if necessary, with water to obtain a solution having a known concentration of about 0.1 mg per mL.

Assay preparation— Transfer an accurately measured volume of Ophthalmic Solution, freshly mixed and free from air bubbles, equivalent to about 50 mg of epinephrine bitartrate, to a 500-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 3.2-mm × 25-cm column that contains packing L1. The flow rate is about 1 mL per minute. Chromatograph the Standard preparation, and record the peak responses as directed under Procedure: the column efficiency determined from the analyte peak is not less than 2000 theoretical plates, the tailing factor for the analyte peak is not more than 2.5, and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 50 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 epinephrine (C9H13NO3) in each mL of the Ophthalmic Solution taken by the formula: in which C is the concentration, in mg per mL, of USP Epinephrine Bitartrate RS in the Standard preparation, V is the volume, in mL, of Ophthalmic Solution taken, and rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.