Topic summary
Carius halogen method
The Carius halogen method in analytical chemistry is a method for the quantitative determination of halogens in organic compounds, invented by the German chemist Georg Ludwig Carius (1829–1875). A variant of it can determine sulfur.
The method uses fuming nitric acid to completely oxidize the carbon, hydrogen, and nitrogen in organic compounds to CO2, H2O, NO, NO2. The halogen present forms the corresponding silver halide (AgX) with a solution of silver nitrate (AgNO3). It is filtered, washed, dried and weighed. Concentrated nitric acid only oxidises iodine to iodic acid and doesn't affect any other halogens. Even the oxidation of iodine by concentrated nitric acid happens only at high temperatures.