Chromatography Forum

Dear all,

I would like to ask you a simple question about the material of the tubing for a 6809N GC. I have read at the User Manual that:

"Gases should be supplied to the instrument only through preconditioned copper tubing (part no. 5180-4196). Do not use ordinary copper tubing—it contains oils and contaminants."

Is there any problem if I use stainless steel tubing instead? Is this a question of pricing, commodity...?

Thank you very much for you attention.

Hi
Do not know what particular downsides with SS there are besides being more ridgid and harder to seal properly.
However they are quite right regarding the preconditioning of tubing. We have had a few cases in this forum in the past, where non-preconditioned tubing was installed causing severe contamination of the GC.

Considering the copper prices today, sure I think you can buy the said tubing cheaper from a good firm than from the supplier, but you need the knowhow to tell them how to precondition.

Make sure your tubing is chromatography grade regardless of what you use. Most people use copper but I've seen stainless with no problems. Spend the savings from stainless on good filters (with visual indicator!) and install close to the instrument.

Stainless steel is prone to leaking unless you solder the connections. And soldering can contribute contamination to your gas supply.

Steel, even stainless can rust with time.

There are reasons why copper is preferred. But it should be cleaned with DCM, 2N acetic acid, and methanol. Then placed into a GC oven (coiled of course) connected to a dry nitrogen gas supply and a restrictor on the end of the coil, with gas flowing, the coil should be warmed overnight (~100°C ?) to remove volatile residues.

Buying pre-cleaned tubing is best.

All tubing should have coils after installation so the tubing has some 'give' to it to reduce stress on the connections. This reduces the chances of developing leaks.

best wishes,

Rod

Stainless steel is prone to leaking unless you solder the connections. And soldering can contribute contamination to your gas supply.

Steel, even stainless can rust with time.

There are reasons why copper is preferred. But it should be cleaned with DCM, 2N acetic acid, and methanol. Then placed into a GC oven (coiled of course) connected to a dry nitrogen gas supply and a restrictor on the end of the coil, with gas flowing, the coil should be warmed overnight (~100°C ?) to remove volatile residues.

Buying pre-cleaned tubing is best.

All tubing should have coils after installation so the tubing has some 'give' to it to reduce stress on the connections. This reduces the chances of developing leaks.

best wishes,

Rod

Hello Rod, I am currently working in a lab where analysis is performed on various biomass samples, we are looking to precondition the stainless steel tubing that will be used on a GC and ASE machines.

Your guide is the most comprehensive instructions on how to do this that we have been able to find on the entire internet thus far. However we are still at a bit of a crossroads as to how to pass the cleaning solvents you mentioned above through the 1 mm (Internal Diameter) stainless steel tubing that we want to use on a GC. If you could provide us with a method or any help at all on how to do this successfully we at Celignis would be very grateful.

Kindest regards,

Gavin.

I would think a modest sized syringe and either a vacuum trap or compressed air source should suffice.

While the greater "we" appreciate the effort of having found the core of a solution to your problem via the search function, we would advise that 4.5 year old threads are not the best candidates for new additions.