Inert gas fusion method is used to analyze the material. A small sample of the material, usually under a gram, is weighed and placed in a graphite crucible. Next, it is burned in a stream of inert gas. Argon or nitrogen is used for hydrogen analysis, while helium is used for the oxygen/nitrogen analysis.
Hydrogen analysis: hydrogen released from the sample is separated from any oxygen and nitrogen discharged from the sample. The hydrogen is then measured by a thermal conductivity cell which determines the percentage by weight of the hydrogen to the sample material.
Oxygen and nitrogen analysis: the oxygen in the sample combines with carbon to form carbon monoxide. The carbon monoxide is converted via a catalyst to carbon dioxide using rare earth copper oxide or platinized silica. The oxygen is measured by an infrared cell which determines the percentage by weight of the oxygen to the sample material.
Molecular nitrogen freed from the same sample is separated from the hydrogen and carbon monoxide released from the sample. The nitrogen is measured by a thermal conductivity cell which determines the percentage by weight of the nitrogen to the sample material.