Standard solution— Transfer 2.0mLof 0.100Niodine VSto a 500-mLvolumetric flask,dilute with water to volume,and mix.

Procedure— Visually examine a portion of the Injection (Test solution)in a suitable clear glass test tube against a white background:it is not pinkish and it contains no precipitate.If any yellow color is observed in the Test solution,concomitantly determine the absorbances of the Test solutionand the Standard solutionin 1-cm cells with a suitable spectrophotometer set at 460nm:the absorbance of the Test solutiondoes not exceed that of the Standard solution.

A: Extract a volume of Injection,equivalent to about 200mg of mepivacaine,with two 10-mLportions of ether,and discard the ether extracts.Render slightly alkaline with sodium carbonate TS,extract the precipitate with ether,evaporate the ether extract on a steam bath to dryness,and dry the residue in vacuum at 60for 1hour:the mepivacaine so obtained melts between 149and 153.

B: It meets the requirements of the tests for Chloride á191ñ.

Ferro-citrate Solution andBuffer Solution— Prepare as directed under Epinephrine Assay á391ñ.

Standard preparation— With the aid of 20mLof sodium bisulfite solution (1in 50),transfer about 25mg of USP Levonordefrin RS,accurately weighed,to a 50-mLvolumetric flask,dilute with water to volume,and mix.Transfer 5mLof this solution to a 50-mLvolumetric flask,dilute with sodium bisulfite solution (1in 500)to volume,and mix to obtain a solution having a known concentration of about 50µg per mL.[NOTE—Make the final dilution at the time the assay is to be carried out.]

Assay preparation— Use the Injection,diluting,if necessary,to obtain a concentration of about 50µg of levonordefrin per mL.

Procedure— Proceed as directed under Epinephrine Assay á391ñ,except to read levonordefrin wherever epinephrine (base)is called for.When the Ferro-citrate Solutionand the Buffer Solutionare mixed with the Assay preparation,a fine precipitate may be formed.Remove this precipitate by centrifugation or by passing through dry filter paper before the colorimetric measurements are taken.Calculate the quantity,in mg,of levonordefrin (C9H13NO3)in each mLof the Injection taken by the formula: in which Cis the concentration,in mg per mL,of USP Levonordefrin RSin the Standard preparation;VFis the final volume of the Assay preparationafter dilution;VTis the volume of Injection taken to prepare the Assay preparation;and AUand ASare the absorbances of the Assay preparationand the Standard preparation,respectively.[NOTE—When dilution of the Injection is not necessary,VF/VTis equal to 1.]