A: It responds to Identification test B under Tetracaine Hydrochloride.

B: The chromatogram of the Assay preparation obtained as directed in the Assay exhibits a major peak for tetracaine, the retention time of which corresponds to that in the chromatogram of the Standard preparation as obtained in the Assay.

Diluent— Prepare a mixture of water and methanol (1:1).

Mobile phase— Prepare a suitable mixture of water, acetonitrile, and methanol (60:20:20) containing 0.06% of sulfuric acid, 0.5% of sodium sulfate, and 0.02% of sodium 1-heptanesulfonate. The pH is about 2.6. Make adjustments if necessary (see System Suitability under Chromatography 621).

Standard preparation— Dissolve an accurately weighed quantity of USP Tetracaine Hydrochloride RS quantitatively in Diluent to obtain a solution having a known concentration of about 1 mg per mL.

Resolution solution— Dissolve a quantity of salicylic acid in a portion of the Standard preparation to obtain a solution containing about 4 mg of salicylic acid and 1 mg of tetracaine hydrochloride per mL.

Assay preparation— Transfer an accurately measured volume of Injection equivalent to about 50 mg of tetracaine hydrochloride, to a 50-mL volumetric flask, dilute with Diluent to volume, and mix.

Chromatographic system (see Chromatography 621)—The liquid chromatograph is equipped with a 305-nm detector and a 3.9-mm × 30-cm column containing packing L1. The flow rate is about 2 mL per minute. Chromatograph the Resolution solution, and record the responses as directed for Procedure: the relative retention times are about 0.8 for salicylic acid and 1.0 for tetracaine; and the resolution, R, between the salicylic acid peak and the tetracaine peak is not less than 2. Chromatograph the Standard preparation, and record the responses as directed for Procedure: the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 5 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the areas for the major peaks. Calculate the quantity, in mg, of tetracaine hydrochloride (C15H24N2O2·HCl) in each mL of the Injection taken by the formula: in which C is the concentration, in mg per mL, of USP Tetracaine Hydrochloride RS in the Standard preparation; V is the volume, in mL, of Injection taken; and rU and rS are the tetracaine peak responses obtained from the Assay preparation and the Standard preparation, respectively.