Topics - Hydrogen generator
Hydrogen is used extensively in gas chromatography both as the combustible gas for the flame ionization detector but also as an alternative to the more expensive helium as a carrier gas (mobile phase). Originally hydrogen was obtained from compressed gas tanks fitted with appropriate reducing valves. However, hydrogen supplied in tanks at high pressure is expensive, take up considerable space, the tanks are heavy and difficult to manage and there is always the risk of fire from leaking valves. Alternatively the hydrogen can be generated electrolytically as desired, under which circumstances the gas can be used as produced, and, thus, no significant amount of gas is accumulated causing fire risk. The hydrogen is produced by passing a current through deionized water, oxygen and other impurities are collected at a nickel electrode and vented to air. The hydrogen ions pass through a tubular palladium cathode where molecular hydrogen is formed and passed out to the chromatograph. The hydrogen is claimed to be 99.99999% pure and can be generated to provide an outlet pressure of up to 100 psi at a flow rate of 300 ml/min.