Identification—
Dissolve 5 Tablets in 40 mL of water in a 250-mL separator. Add 3 mL of sodium hydroxide solution (1 in 2), and extract with two 50-mL portions of chloroform. Extract the combined chloroform extracts in a 250-mL separator with two 15-mL portions of 0.5 N hydrochloric acid, and evaporate the combined aqueous extracts on a steam bath to dryness. Dissolve the residue in 5 mL of acetone, and add 50 mL of anhydrous ether to the solution. On standing, phenmetrazine hydrochloride will crystallize out. Filter the precipitate, wash with anhydrous ether, and dry at 105
: the crystals so obtained melt within a range of 3
between 172
and 182
(see
Melting Range or Temperature 
741
).
Dissolution 711—
Medium:
water; 900 mL.
Apparatus 2:
50 rpm.
Time:
45 minutes.
Procedure—
Determine the amount of C
11H
15NO·HCl dissolved from UV absorbances at the wavelength of maximum absorbance at about 256 nm on filtered portions of the solution under test, suitably diluted with
Dissolution Medium, if necessary, in comparison with a Standard solution having a known concentration of
USP Phenmetrazine Hydrochloride RS in the same
Medium.
Tolerances—
Not less than 75% (Q) of the labeled amount of C11H15NO·HCl is dissolved in 45 minutes.
Assay—
Weigh and finely powder not fewer than 20 Tablets. Transfer an accurately weighed portion of the powder, equivalent to about 250 mg of phenmetrazine hydrochloride, to a 250-mL volumetric flask, add about 125 mL of 0.5 N hydrochloric acid, shake by mechanical means for 1 hour, dilute with 0.5 N hydrochloric acid to volume, and mix. Transfer 50.0 mL of the solution to a 250-mL separator, add 5 mL of sodium hydroxide solution (1 in 2), and extract with four 50-mL portions of chloroform, collecting the chloroform extracts in a second 250-mL separator. Extract the combined chloroform extracts with six 15-mL portions of 0.5 N hydrochloric acid, collecting the aqueous extracts in a 100-mL volumetric flask, and dilute with 0.5 N hydrochloric acid to volume to obtain the
Assay preparation. Concomitantly determine the absorbances of the
Assay preparation and of a Standard solution of
USP Phenmetrazine Hydrochloride RS in the same medium, having a known concentration of about 500 µg per mL, in 1-cm cells, at the wavelength of maximum absorbance at about 256 nm, with a suitable spectrophotometer, using 0.5 N hydrochloric acid as the blank. Calculate the quantity, in mg, of C
11H
15NO·HCl in the portion of Tablets taken by the formula:
0.5C(AU / AS),
in which
C is the concentration, in µg per mL, of
USP Phenmetrazine Hydrochloride RS in the Standard solution, and
AU and
AS are the absorbances from the
Assay preparation and the Standard solution, respectively.
