Identification—
A:
Extract a quantity of powdered Tablets, equivalent to about 500 mg of niacinamide, with two 10-mL portions of alcohol, evaporate the filtered alcohol extracts on a steam bath, and dry at 80
for 2 hours: the IR absorption spectrum of a potassium bromide dispersion of the residue so obtained exhibits maxima only at the same wavelengths as that of a similar preparation of
USP Niacinamide RS.
B:
From the niacinamide obtained in
Identification test
A, prepare a solution (1 in 50,000), and determine the absorbance of this solution in a 1-cm cell at 245 nm and at 262 nm, with a suitable spectrophotometer, using water as the blank: the ratio
A245/
A262 is between 0.63 and 0.67.
Dissolution, Procedure for a Pooled Sample 
711
—
Medium:
water; 900 mL.
Apparatus 2:
50 rpm.
Time:
45 minutes.
Procedure—
Determine the amount of C
6H
6N
2O dissolved, employing the procedure set forth in the
Assay for niacin or niacinamide, pyridoxine hydrochloride, riboflavin, and thiamine under
Water-soluble Vitamins Tablets, using 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 Niacinamide RS in the same medium.
Tolerances—
Not less than 75% (Q) of the labeled amount of C6H6N2O is dissolved in 45 minutes.
Assay—
Proceed with Tablets as directed for
Chemical Method under
Niacin or Niacinamide Assay 441, using
Standard Niacinamide Preparation as the
Standard Preparation in the
Assay Procedure: and the following as the
Assay Preparation. Weigh and finely powder not less than 10 Tablets. Weigh accurately a quantity of the powder, equivalent to about 25 mg of niacinamide, and transfer with the aid of about 50 mL of water to a 250-mL volumetric flask. Heat, if necessary, until no more dissolves, cool, dilute with water to volume, and mix. Pipet 10 mL of the solution into a 100-mL volumetric flask, dilute with water to volume, and mix. Calculate the quantity, in mg, of C
6H
6N
2O in the portion of Tablets taken by the formula:
25(AU / AS).
