Identification—
A:
Cool a mixture of 10 mL of Injection and 10 mL of 3 N hydrochloric acid in an ice bath to 0
, add 5 mL of sodium nitrite solution (1 in 5), stirring gently, and 2 mL of a solution of 0.1 g of 2-naphthol in 5 mL of 1 N sodium 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 
191
.
C:
To about 25 mL of Injection add 1 drop of
ferric chloride TS: the solution immediately turns a light green and changes to a light blue within 1 minute. Add 2 drops of 3 N hydrochloric acid: the color reverts to light green (
presence of levonordefrin).
Assay for propoxycaine and procaine hydrochlorides—
Standard propoxycaine hydrochloride preparation—
Prepare, by quantitative and stepwise dilution, a solution in dilute hydrochloric acid (1 in 6) containing about 50 µg of
USP Propoxycaine Hydrochloride RS, accurately weighed, in each mL.
Standard procaine hydrochloride preparation—
Prepare, by quantitative and stepwise dilution, a solution in dilute hydrochloric acid (1 in 6) containing about 200 µg of
USP Procaine Hydrochloride RS, accurately weighed, in each mL.
Assay preparation—
Transfer an accurately measured volume of Injection, equivalent to about 100 mg of procaine hydrochloride, to a 125-mL separator containing 25 mL of chloroform and 10 mL of water. Add 5 mL of
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-mL portions of chloroform, adding the extracts to the second separator. Extract the combined chloroform extracts with 35 mL of dilute hydrochloric acid (1 in 6), transfer the chloroform to a third separator, and transfer the acid extract to a 100-mL volumetric flask. Extract the chloroform with two 10-mL portions of dilute hydrochloric acid (1 in 6), add the acid extracts to the volumetric flask, add dilute hydrochloric acid (1 in 6) to volume, and mix. Transfer 15.0 mL of this solution to a second 100-mL volumetric flask, add dilute hydrochloric acid (1 in 6) to volume, and mix.
Procedure—
Concomitantly determine the absorbances of the
Standard preparations and the
Assay preparation in 1-cm cells at 296 and 272 nm, with a suitable spectrophotometer, using water as the blank. Calculate the quantity, in mg, of propoxycaine hydrochloride (C
16H
26N
2O
3·HCl) in each mL of the Injection taken by the formula:
(0.667
C / V)(
A296A4 
A272A3)
/ (
A1A4 A2A3),
in which
C is the concentration, in µg per mL, of
USP Propoxycaine Hydrochloride RS in the
Standard propoxycaine hydrochloride preparation.
Calculate the quantity, in mg, of procaine hydrochloride (C13H20N2O2·HCl) in each mL of the Injection taken by the formula:
(0.667
C / V)(
A272A1 A296A2)
/ (
A1A4 A2A3),
in which
C is the concentration, in µg per mL, of
USP Procaine Hydrochloride RS in the
Standard procaine hydrochloride preparation,
V is the volume, in mL, of Injection taken,
A1 and
A2 are the absorbances of the
Standard propoxycaine hydrochloride preparation at 296 and 272 nm, respectively,
A3 and
A4 are the absorbances of the
Standard procaine hydrochloride preparation at 296 and 272 nm, respectively, and
A296 and
A272 are the absorbances of the
Assay preparation at 296 and 272 nm, respectively.
Assay for levonordefrin—
Ferro-citrate solution,
Buffer solution, and
Standard preparation—Prepare as directed under
Epinephrine Assay 391.
Procedure—
Proceed as directed for
Procedure under
Epinephrine Assay 391. Calculate the quantity, in mg, of levonordefrin (C
9H
13NO
3) in each mL of the Injection taken by the formula:
(183.21 / 333.30)(0.05C / V)(AU / AS),
in which 183.21 and 333.30 are the molecular weights of levonordefrin and epinephrine bitartrate, respectively,
C is the concentration, in µg per mL, of
USP Epinephrine Bitartrate RS in the
Standard preparation, and
V is the volume, in mL, of Injection taken.
