Chromatography Forum

Hi,

I am using GC-MS analysis for VFA determination. i was having carry over issues, so today i removed my liner and saw there are lots of lints from my septum as well as some other impurities that one can see by naked eyes. Now in the manual states that i should clean it in ultrasonic bath with acetone-methanol (1:1) mixture. Now the chemicals i have but not the ultrasonic bath. Is there any other way of cleaning the liner instead of in ultrasonic bath. I am using a single tappered liner.

Regards!

Try a thin pipe cleaner, or you can get tiny bottle brushes in inlet maintenance kits from Restek, Supelco etc. Failing that a lab tissue rolled into a cylinder, or a cotton bud. If you have brown or black deposits they will be very difficult to remove with solvents.

Peter

why not just take a new liner?
It might cost more in labour-time than the cost of a new liner.

I agree with BMU-VMW, moreover by cleaning the miner with sharp brushes you might remove the superficial treatment that makes it inert

Put your liner in chromic acid for 5 days, after, rince with water and acetone.
After this treatment, i pass liner on flame

Put your liner in chromic acid for 5 days, after, rince with water and acetone.
After this treatment, i pass liner on flame

just don't expect it to be deactivated anymore.

It is usually best to rinse with solvent and if that doesn't do it pitch it.

We normally soak with solvent and rinse, or use acid if there are inorganic deposits. If they are highly contaminated we will fire them in the muffle furnace at 600C for a few hours. We then silanize them again to deactivate them. We go through so many that it actually pays us to do them ourselves, usually in large batches.

If I had a single instrument I would probably just buy new ones.

How do you re-silanise liners? I have 6 GC/MS so recycling them is a good option. We had a commercal mob doing them but they have ceased to do it. We have tried cleaning in MeOH, then cook on 400C furnace overnight, then re-silanise with glass treet or DMDCS (5% in Toluene). We analyse illicit drugs, and found that when we re-silanised them using a cold (wash type) process, we would not be able to see Morphine until after a number of injections had de-activated the liners. I know you say just buy new ones but here in Oz they charge $40 each for liners.
So does anyone have a good,workable not to toxic process?

loopylinda, honestly, work out the cost of employing someone to re-activate your liners, add the cost of the chemicals needed to do it; then add the cost of wasted GC runs where you know you'll miss things (instrument time = money; how much does an hour of instrument time cost you, when you consider the capital cost of the instrument and the room it's sitting in... not to mention spares, gas-supplies, and service costs)? Then add the losses caused by analyses you don't trust, and validation issues where you're having to validate liners that you know don't always work.... you may find that $40 per liner is cheaper than what you're doing at the moment!

We used to clean liners until we found similar issues to those reported by loopylinda. Depressingly, different chemicals behave differently, and every washed-and-resilanised liner had its own unique behaviour. Fresh, commercial liners are far more uniform, which gives uniform, guaranteed results.

I guess you probably don't work for the government !! Thanks all the same, I guess you are right, we were getting them commercially cleaned and re-silanised at $7 each, but now will have to buy them.
can you suggest a cheaper supplier the cheapest I can get are about $25 each.

I'm not in the same country, loopylinda, so I can't easily advise.... but governments differ too. The flavour here is now very much to analyse costs in great detail, presumably to assure ourselves we're not wasting public money. Sometimes, as a member of the public, I worry whether we're spending more checking that we're not being wasteful than we were wasting before we did all the checking.

I guess you probably don't work for the government !!

In fact I am.
But what's more important: numbers beeing sheep or beeing correct ?