A: It meets the requirements under Identification—Organic Nitrogenous Bases 181.

B: Extract a volume of Injection, equivalent to about 200 mg of mepivacaine, with two 10-mL portions of ether, and discard the ether extracts: the remaining solution meets the requirements for Identification test B under Mepivacaine Hydrochloride.

pH 6.3 Phosphate buffer— Dissolve 3.40 g of monobasic potassium phosphate and 4.35 g of dibasic potassium phosphate in 1000 mL of water, and adjust, if necessary, with potassium hydroxide or phosphoric acid to a pH of 6.3.

Mobile phase— Prepare a filtered and degassed mixture of pH 6.3 Phosphate buffer and acetonitrile (65:35). Make adjustments if necessary (see System Suitability under Chromatography 621).

System suitability preparation— Dissolve suitable amounts of methylparaben and USP Mepivacaine Hydrochloride RS in an appropriate volume of Mobile phase to obtain a solution containing about 0.05 mg per mL and 1.0 mg per mL, respectively.

Standard preparation— Dissolve an accurately weighed quantity of USP Mepivacaine Hydrochloride RS in Mobile phase, and dilute quantitatively, and stepwise if necessary, with Mobile phase to obtain a solution having a known concentration of about 1.0 mg per mL.

Assay preparation— Transfer a volume of Injection, equivalent to about 100 mg of mepivacaine hydrochloride, to a 100-mL volumetric flask, dilute with Mobile phase to volume, and mix.

Chromatographic system (see Chromatography 621)— The liquid chromatograph is equipped with a 263-nm detector and a 4.6-mm × 25.0-cm column that contains 5-µm packing L1.* The flow rate is about 1.0 mL per minute. The column temperature is maintained at 40. Chromatograph the System suitability preparation, and record the peak responses as directed for Procedure: the relative retention times are about 1.4 for methylparaben and 1.0 for mepivacaine; the resolution, R, between methylparaben and mepivacaine is not less than 2.0; the capacity factor, k¢, for the mepivacaine peak is not less than 1.0; and the tailing factor for the mepivacaine peak is not more than 2.0. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 10 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the mepivacaine peaks. Calculate the quantity, in mg, of mepivacaine hydrochloride (C15H22N2O·HCl) in the volume of Injection taken by the formula: in which C is the concentration, in mg per mL, of USP Mepivacaine Hydrochloride RS in the Standard preparation; and rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.