Standard preparation—
Transfer about 30 mg of
USP Tolazoline Hydrochloride RS, accurately weighed, to a 100-mL volumetric flask, dissolve in and dilute with methanol to volume, and mix.
Procedure—
Transfer 3.0 mL each of the
Standard preparation, the
Assay preparation, and methanol to provide the blank, to separate 25-mL volumetric flasks. To each flask add 1 mL of 0.5 N sodium hydroxide and 1 mL of dilute sodium nitroferricyanide TS (1 in 2), mix, and allow to stand for 10 minutes. Add 3 mL of sodium bicarbonate solution (1 in 12) to each flask, dilute with water to volume, mix, and allow to stand for 10 minutes. Concomitantly determine the absorbances of the solutions in 1-cm cells at the wavelength of maximum absorbance at about 565 nm, with a suitable spectrophotometer, against the blank. Calculate the quantity, in mg, of C
10H
12N
2·HCl in each mL of the Injection taken by the formula:
(0.5C / V)(AU / AS),
in which
C is the concentration, in µg per mL, of
USP Tolazoline Hydrochloride RS in the
Standard preparation,
V is the volume, in mL, of Injection taken, and
AU and
AS are the absorbances of the solutions from the
Assay preparation and the
Standard preparation, respectively.
197K
—Obtain the test specimen as follows. Steam-distill a volume of Injection, equivalent to about 250 mg of tolazoline hydrochloride, for 5 to 10 minutes, and discard the distillate. Transfer the remaining solution to a separator, add about 2 mL of 1 N sodium hydroxide, and extract with 20 mL of ether. Filter the ether extract through cotton into a beaker, evaporate to dryness, and dry the residue in vacuum over silica gel for 4 hours.