Identification
A:
Cool a mixture of 10mLof Injection and 10mLof 3Nhydrochloric acid in an ice bath to 0

,add 5mLof sodium nitrite solution (1in 5),stirring gently,and 2mLof a solution of 0.1g of 2-naphthol in 5mLof 1Nsodium hydroxide,and observe immediately:a bright orange-red precipitate is formed (
presence of a primary aminophenyl group).
B:
It responds to the tests for Chloride á191ñ.
C:
To about 5mLof Injection add 1drop of ferric chloride TS:a green color develops (presence of norepinephrine bitartrate).
Assay for propoxycaine and procaine hydrochlorides
Standard propoxycaine hydrochloride preparation
Prepare,by quantitative and stepwise dilution,a solution in 2Nhydrochloric acid containing about 50µg of
USP Propoxycaine Hydrochloride RS,accurately weighed,in each mL.
Standard procaine hydrochloride preparation
Prepare,by quantitative and stepwise dilution,a solution in 2Nhydrochloric acid containing about 200µg of
USP Procaine Hydrochloride RS,accurately weighed,in each mL.
Assay preparation
Transfer an accurately measured volume of Injection,equivalent to about 100mg of procaine hydrochloride,to a 125-mLseparator containing 25mLof chloroform and 10mLof water.Add 5mLof sodium carbonate TS,shake vigorously,allow the layers to separate,and transfer the chloroform layer to a second separator.Extract the aqueous layer with two 10-mLportions of chloroform,adding the extracts to the second separator.Extract the combined chloroform extracts with 35mLof 2Nhydrochloric acid,transfer the chloroform to a third separator,and transfer the acid extract to a 100-mLvolumetric flask.Extract the chloroform with two 10-mLportions of 2Nhydrochloric acid,add the acid extracts to the volumetric flask,dilute with 2Nhydrochloric acid to volume,and mix.Transfer 15.0mLof this solution to a second 100-mLvolumetric flask,dilute with 2Nhydrochloric acid to volume,and mix.
Procedure
Concomitantly determine the absorbances of the Standard preparationsand the Assay preparation,in 1-cm cells,at 296nm and 272nm,with a suitable spectrophotometer,using water as the blank.
Calculate the quantity,in mg,of propoxycaine hydrochloride (C16H26N2O3·HCl)in each mLof the Injection taken by the formula:
(0.667C/V)(A296A4-A272A3)/(A1A4-A2A3),
in which
Cis the concentration,in µg per mL,of
USP Propoxycaine Hydrochloride RSin the
Standard propoxycaine hydrochloride preparation,
Vis the volume,in mL,of Injection taken,
A1and
A2are the absorbances of the
Standard propoxycaine hydrochloride preparationat 296nm and 272nm,respectively,
A3and
A4are the absorbances of the
Standard procaine hydrochloride preparationat 296nm and 272nm,respectively,and
A296and
A272are the absorbances of the
Assay preparationat 296nm and 272nm,respectively.
Calculate the quantity,in mg,of procaine hydrochloride (C13H20N2O2·HCl)in each mLof the Injection taken by the formula:
(0.667C/V)(A272A1-A296A2)/(A1A4-A2A3),
in which
Cis the concentration,in µg per mL,of
USP Procaine Hydrochloride RSin the
Standard procaine hydrochloride preparation,and
Vis the volume,in mL,of Injection taken.
Assay for norepinephrine
Assay preparation
Prepare as directed for
Assay Preparation under
Epinephrine Assay á391ñexcept to read norepinephrinewhere epinephrineis specified.
Procedure
Proceed as directed for
Procedureunder
Epinephrine Assay á391ñ.Calculate the quantity,in mg,of norepinephrine (C
8H
11NO
3)in each mLof the Injection taken by the formula:
(169.18/319.27)(0.05C/V)(AU/AS),
in which 169.18and 319.27are the molecular weights of norepinephrine and norepinephrine bitartrate,respectively,
Cis the concentration,in µg per mL,calculated on the anhydrous basis,of
USP Norepinephrine Bitartrate RSin the
Standard preparation,and
Vis the volume,in mL,of Injection taken.