Topics - Hydrogen
Hydrogen is diatomic gas having a molecular weight of 2 and is used in chromatography, almost exclusively, to provide the combustion gas in a flame ionization detector (FID). In the early days of gas chromatography hydrogen was also used as a carrier gas and the carrier gas was burnt directly at a small jet in both the flame thermocouple detector and the FID. The use of hydrogen as a carrier gas also improved column efficiency. However, hydrogen as a carrier gas has two disadvantages, one its inflammability and two, its tendency to hydrogenate labile substances during their passage through the column. Hydrogen is not a desirable gas to have piped around a laboratory but unfortunately the very popular FID detector and the NPD detector demand its use. As a result hydrogen generators have found popularity, as they produce hydrogen by electrolysis as required and, thus, significantly reduce any fire risk. The advantages in column performance that is provided by using hydrogen as a carrier gas can be partially realized by using helium as the carrier gas.