A: It meets the requirements under Identification—Organic Nitrogenous Bases á181ñ.

B: Extract a volume of Injection,equivalent to about 200mg of mepivacaine,with two 10-mLportions of ether,and discard the ether extracts:the remaining solution meets the requirements for Identificationtest Bunder Mepivacaine Hydrochloride.

pH6.3Phosphate buffer— Dissolve 3.40g of monobasic potassium phosphate and 4.35g of dibasic potassium phosphate in 1000mLof water,and adjust,if necessary,with potassium hydroxide or phosphoric acid to a pHof 6.3.

Mobile phase— Prepare a filtered and degassed mixture of pH6.3Phosphate bufferand acetonitrile (65:35).Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

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

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

Assay preparation— Transfer a volume of Injection,equivalent to about 100mg of Mepivacaine Hydrochloride,to a 100-mLvolumetric flask,dilute with Mobile phaseto volume,and mix.

Chromatographic system(see Chromatography á621ñ)— 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 1.0mLper 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 1.4for methylparaben and 1.0for 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;the tailing factor for the mepivacaine peak is not more than 2.0;and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 10µL)of the Standard preparationand the Assay preparationinto 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 Cis the concentration,in mg per mL,of USP Mepivacaine Hydrochloride RSin the Standard preparation;and rUand rSare the peak responses obtained from the Assay preparationand the Standard preparation,respectively.