Nitrogen, helium and hydrogen are commonly used carrier gases in gas chromatography (GC). Hydrogen offers several benefits over the other gases, such as a reduction of the time of analysis, improved sensitivity and resolution, and lower cost. In addition, hydrogen can be used as fuel gas for flame-ionization detectors (FID) or as a reaction gas for electrolytic conductivity detectors (ELCD, or Hall detectors).
Laboratories can obtain hydrogen in gas cylinders, or generate hydrogen on site using a hydrogen generator. Hydrogen cylinders present some potential safety concerns because hydrogen is flammable. In addition, hydrogen purity may vary from one cylinder to another. Hydrogen generators eliminate the need for storage of hydrogen, thereby reducing safety concerns. They use electrolytic dissociation of water to generate a continuous supply of hydrogen. A palladium membrane is often used to remove residual water and other contaminants from the hydrogen produced. This allows the production of very high purity hydrogen.