As the name implies, a CHN Analyzer is a scientific instrument which can determine the elemental concentrations in a given sample. It is used to measure Carbon (C), Hydrogen (H) and Nitrogen (N). Sample sizes may differ depending on system, but most often in around a few mg. For some sample matrices larger mass is preferred due to sample heterogenicity.
This instrument uses combustion to oxidize the sample into simple compounds which are then detected with thermal conductivity detection or infrared spectroscopy. Separation of interference is done by chemical reagents.