AOAC Official Method 938.14 Phenazopyridine Hydrochloride in Drugs
Titrimetric Method
First Action 1938
Final Action
A. Reagents
(a) Titanium trichloride standard solution.—Prepare as in 948.28A (see A.1.15) and standardize as in 948.28B (see A.1.15).
(b) Light green SF yellowish solution.—Dissolve 1 g [use C.I. No. 42095 (FD&C Green 2)] in H2O and dilute to 1 L.
B. Preparation of Test Solution
( a ) S o l u t i o n s.—To volume c o n t a i n i n g c a 0 . 1 g phenazopyridine×HCl, add 10mL0.1M HCl and dilute to 100 mL.
(b) Tablets and jelly.—Accurately weigh laboratory sample (powdered i n case of t a b l e t s ) containing ca 0.1 g phenazopyridine×HCl, add 10mL0.1M HCl, and dilute to 100 mL.
(c) Ointments.—Accurately weigh, in 100mLbeaker, laboratory sample containing ca 0.1 g phenazopyridine×HCl, stir with ether until ointment base dissolves, and wash into separator with ether and H2O. Shake thoroughly, and drain aqueous layer into second separator containing 25mLether. Shake, and drain aqueous layer into third separator containing 25 mL ether. Shake, and transfer aqueous layer to 250 mL beaker. Wash ether layers with alternate 10 mL portions HCl (1 + 1) and H2O until no more color is removed, successively passing each portion of the HCl or H2O through the 3 separators and finally into beaker. Nearly neutralize combined acid extracts with NH4OH, cool, wash into separator, make ammoniacal, and extract with 25 mL portions CHCl3 until no more color is removed, filtering CHCl3 through cotton pledget in stem of separator. Evaporate combined CHCl3 extracts just to dryness, take up in 10 mL 0.1M HCl, and dilute to 100 mL.
