AOAC Official Method 932.19 Bismuth Compounds in Drugs Gravimetric Method
First Action 1932
Final Action 1965
(Applicable in absence of Pb.)
Caution: See Appendix B, safety notes on distillation, nitric acid, and hydrogen sulfide.
Thoroughly mix test sample and weigh 0.5 g into 500mLKjeldahl flask. Ignite gently over small flame, using wire gauze under flask, and increase heat towards end. Let cool, add 15–20mLHNO3, evaporate to dryness, and ignite as before until yellow or orange Bi2O3 is formed. Cool residue and dissolve in 10–15 mL warm HNO3, using fewmL3%H2O2 if residue does not dissolve readily. Boil off excess H2O2 and wash into 400 mL beaker withH2O, rinsing flask well. Dilute to ca 200 mL, make just neutral to litmus with NH4OH, and add 5 mL HCl. Precipitate with H2S completely.
