Identification—
Transfer a quantity of finely ground Tablets, equivalent to about 50 mg of phenazopyridine hydrochloride, to a 125-mL separator, add 50 mL of water, 1 mL of 1 N hydrochloric acid, and 5 mL of a saturated sodium chloride solution, and shake to dissolve. Extract with two 25-mL portions of chloroform, and discard the chloroform. Add 5 mL of 1 N sodium hydroxide to the aqueous solution, and extract with one 50-mL portion of chloroform. Transfer the chloroform layer to a second 125-mL separator, and wash with one 50-mL portion of 0.1 N sodium hydroxide. Filter the chloroform layer through a pledget of cotton previously washed with chloroform. Add 5 drops of hydrochloric acid to the filtrate, and evaporate under a current of air on a steam bath to dryness. Add 5 mL of alcohol, and evaporate. Dry the residue at 105
for 4 hours: the IR absorption spectrum of a potassium bromide dispersion of the dried residue so obtained exhibits maxima only at the same wavelengths as that of a similar preparation of
USP Phenazopyridine Hydrochloride RS.
Dissolution 
711
—
Medium:
water; 900 mL.
Apparatus 2:
50 rpm.
Time:
45 minutes.
Procedure—
Determine the amount of C
11H
11N
5·HCl dissolved from UV absorbances at the wavelength of maximum absorbance at about 422 nm on filtered portions of the solution under test, suitably diluted with
Dissolution Medium in comparison with a Standard solution having a known concentration of
USP Phenazopyridine Hydrochloride RS in the same
Medium.
Tolerances—
Not less than 75% (Q) of the labeled amount of C11H11N5.HCl is dissolved in 45 minutes.
Assay—
Phosphate buffer—
Dissolve 2.64 g of dibasic ammonium phosphate in about 900 mL of water. Adjust with phosphoric acid to a pH of 3.0, dilute with water to 1000 mL, and mix.
Mobile phase—
Prepare a mixture of
Phosphate buffer and methanol (50:50). Make adjustments if necessary (see
System Suitability under
Chromatography 621).
Standard preparation—
Transfer about 50 mg of
USP Phenazopyridine Hydrochloride RS, accurately weighed, to a 100-mL volumetric flask. Add 50 mL of methanol, and swirl to dissolve. Dilute with
Phosphate buffer to volume, mix, and pass through a filter having a 0.5-µm or finer porosity.
Assay preparation—
Weigh and finely powder not fewer than 20 Tablets. Transfer an accurately weighed portion of the powder, equivalent to about 100 mg of phenazopyridine hydrochloride, to a 200-mL volumetric flask. Add 100 mL of methanol, and sonicate for 10 minutes. Add about 75 mL of Phosphate buffer, and sonicate for an additional 10 minutes, with occasional mixing. Dilute with Phosphate buffer to volume, and mix. Pass this solution through a filter having a 0.5-µm or finer porosity.
Chromatographic system (see Chromatography 621)—
The liquid chromatograph is equipped with a 220-nm detector and a 3.9-mm × 30-cm column that contains packing L1. The flow rate is about 1.5 mL per minute. Chromatograph the
Standard preparation, and record the responses as directed for
Procedure: the column efficiency is not less than 1400 theoretical plates; the tailing factor for the analyte peak is not more than 2.0; and the relative standard deviation for replicate injections is not more than 2.0%.
Procedure—
Separately inject equal volumes (about 10 µL) of the
Standard preparation and the
Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in mg, of C
11H
11N
5. HCl in the portion of Tablets taken by the formula:
200C(rU / rS),
in which
C is the concentration, in mg per mL, of
USP Phenazopyridine Hydrochloride RS in the
Standard preparation; and
rU and
rS are the phenazopyridine peak responses obtained from the
Assay preparation and the
Standard preparation, respectively.
