Identification—
A:
The UV absorption spectrum, measured in the region between 250 and 350 nm, of a dilution of Injection in 0.01 N methanolic sodium hydroxide containing ketamine hydrochloride equivalent to about 800 µg of ketamine per mL, exhibits maxima and minima at the same wavelengths as that of a similar preparation of
USP Ketamine Hydrochloride RS, concomitantly measured.
B:
The UV absorption spectrum of the solution employed for measurement of absorbance of the assay solution, prepared as directed in the
Assay, exhibits maxima and minima at the same wavelengths as that of the Standard solution, prepared as directed in the
Assay.
Assay—
Transfer an accurately measured volume of Injection, equivalent to about 500 mg of ketamine hydrochloride, to a 200-mL volumetric flask, dilute with water to volume, and mix. Transfer 20.0 mL of this solution to a 125-mL separator, add 3 mL of 0.1 N sodium hydroxide, and extract with three 15-mL portions of chloroform. Collect the chloroform extracts in a second 125-mL separator, and extract with three 30-mL portions of 0.1 N sulfuric acid, collecting the acid extracts in a 200-mL volumetric flask. Dilute with 0.1 N sulfuric acid (saturated with chloroform) to volume, and mix. Concomitantly determine the absorbances of this solution and a Standard solution of
USP Ketamine Hydrochloride RS in the same medium having a known concentration of about 250 µg per mL, in 1-cm cells at the wavelength of maximum absorbance at about 269 nm, with a suitable spectrophotometer, using 0.1 N sulfuric acid (saturated with chloroform) as the blank. Calculate the quantity, in mg, of ketamine (C
13H
16ClNO) in each mL of the Injection taken by the formula:
(237.73 / 274.19)(2C / V)(AU / AS),
in which 237.73 and 274.19 are the molecular weights of ketamine and ketamine hydrochloride, respectively;
C is the concentration, in µg per mL, of
USP Ketamine Hydrochloride RS in the Standard solution;
V is the volume, in mL, of Injection taken; and
AU and
AS are the absorbances of the solution from the Injection and the Standard solution, respectively.
85
—
It contains not more than 0.4 USP Endotoxin Unit per mg of ketamine hydrochloride.