Chromatography Forum

Is it necessary to use purified grade compressed air for Gas Chromatography or is it alright to use industrial grade compressed air?

It all depends on your application: If you use said air as fuel for your FID, you really should use purified air (as in methane-free zero-air).

The only, sub-par but working alternative is air from an oil-free compressor, filtered with molsieve and charcoal. That way, you still have around 20 ppm of methane in your air and a somewhat unstable baseline but it works.

Any air coming from an oil-sealed compressor is unfit for GC purposes as you'd overload the zero-air generator and poison the platinum catalyst.

Industrial grade compressed air can vary widly in quality. I worked in labs that have had compressed air provided by the company or institution. At one place, you could open the air line into the room and smell the oil present in the compressed air. At another the quality of the air was pretty good - untill there was a failure to change filters on the air compressor system - then we had increased water vapor levels in the air making it to the labs.