A CHN Analyzer is a scientific instrument which can determine the elemental composition of a sample. The name derives from the three primary elements measured by the device: carbon (C), hydrogen (H) and nitrogen (N). Sulfur (S) and oxygen (O) can also be measured. Such analyzers usually use very small quantities, many times around 1 to 3 mg of the sample. The analyzer uses a combustion process to break down substances into simple compounds which are then quantified, usually by infrared spectroscopy.