Bismuth Citrate:
Identification:
A: Infrared Absorption 197K : on the undried specimen.
B: When strongly heated, the salt chars, and on ignition leaves a more or less blackened residue having a yellow surface. The residue is soluble in warm nitric acid, and this solution, when dropped into a large excess of water, produces a white turbidity.
C: Dissolve 1 g in ammonia. When treated with hydrogen sulfide in excess, a black precipitate is obtained. Filter this mixture, drive off the excess hydrogen sulfide by heating, and allow to cool. To a portion of this cooled solution add an excess of calcium hydroxide and boil: a white precipitate is formed. Reserve a second portion of the cooled solution for the test for Limit of nitrate.
Arsenic: the limit is 10 microgm per g.