AOAC Official Method 934.09 Merbromin in Drugs
First Action 1934
A. Tests for Purity—Procedure
(a) Acidify portion of merbrom in laboratory solution with 10% H2SO4 (w/v) and filter off precipitate. Filtrate is only slightly yellow.
(b) PassH2Sinto portion of filtrate.Noprecipitate or coloring occurs.
(c) Add few mL 10% HNO3 to another portion of filtrate and add 0.1M AgNO3 solution. No precipitate forms.
B. Total Solids in Laboratory Solution—Final Action Pipet 10 mL merbromin solution into tared, extra-wide-form weighing bottle and evaporate to dryness on steam bath. Let dry overnight in open bottle in desiccator containing H2SO4. Weigh.
C. Determination of Mercury—Final Action Pipet 10 mL ca 2% merbromin laboratory solution into 500 mL tall beaker and evaporate to dryness on steam bath (or accurately weigh ca 0.2 g powder). Dissolve residue in 4 mL H2O and slowly add, with constant mixing, 10 mL H2SO4. Incline beaker and cautiously add small portions finely powdered KMnO4, mixing after each addition, until deep purple color shows that considerable excess
has been added. Let stand 30 min, mixing occasionally. Mixture should still be purple.
