AOAC Official Method 974.40 Guaifenesin in Drugs
Polarographic Method
First Action 1974
Final Action 1974
(Not applicable in presence of salicylate.)
A. Apparatus
(a) Polarograph.—Any voltammetric or polarographic instrument with necessary accessories (cells, electrodes, Hg, capillaries) capable of scanning up to 3.0Vin either positive or negative direction.
(b) Micro or standard cell, H-shaped.—Saturated calomel electrode, with 3% KCl-agar plug.
(c) Water bath.—Maintain at 65 ± 1°C in freely circulating H2O bath.
B. Reagents
(a) Potassium nitrate solution.—1M. Weigh 50.5 g KNO3 into 500 mL volumetric flask, dilute to volume with H2O, and mix.
(b) Dilute sulfuric acid solution.—10% (v/v). Dilute 20 mL H2SO4 (1 + 1) to 100 mL with H2O and mix.
(c) Gelatin maximum suppressor.—1 mg/mL. Accurately weigh 100 mg gelatin into 100 mL volumetric flask, and dissolve in small amount H2O on steam bath. Cool, dilute to volume with H2O, and mix. Prepare fresh daily, as needed.
