Chromatography Forum

I am working with an Agilent 7890A GC with methanizer (nickel catalyst). My 1 ppm CO/CO2 standards are generating RF's of 0.00023 whereas all other standards (10-2500 ppm CO/CO2) are generating RF's averaging 0.00044. Does anyone know if the difference between my lowest standard and the others is normal or is my methanizer not converting efficiently. Is there a way to clean the nickel catalyst to remove any contaminants such as carbon build up? One of the most problematic balance gases that I have to work with is ethylene and some methanizer contamination has occurred. Thanks in advance for any good advice.

To remove contaminants (polymerized ethylene and sulfur compounds) which poison the catalyst you have to heat the methanizer to very high temperatures (>600°C) purging it with oxygen or air. [Doesn't always work, either]

It is much cheaper and prudent to replace or repack the methanizer with new catalyst.

best wishes,

Rodney George