GC Maintenance (Pesticide-related)

[chemwipe]

When performing maintenance (cutting guard and/or analytical columns, changing Presstight connectors, liners, baseplates, septa, etc.), is there any benefit to cleaning the injection port with solvent?

I usually use methanol or acetone and a cotton swab - does this really make a difference?

Just curious because my Endrin/DDT degradation solution will sometimes pass without cleaning the port. It usually seems like I have a bad liner or I need to change the baseplate.

Thanks,
cw

[Peter Apps]

Hi Chemwipe

If by injection port you mean the metal body into which the glass liner fits, swabbing with solvent should not make much difference, because the sample should never get anywhere near the metal - that's what the glass liner is there for. Having said that I have seen injector bodies so crudded up by repeated injections of filthy samples that the liner was glued into the body !

Be cautious when swabbing because on some GCs there is a chance of getting solvent into the carrier gas lines (on the brand that I suspect that you are using the gas lines connect to the top fitting that you will have screwed off).

Peter

[Peter Apps]

Hi Chemwipe

If by injection port you mean the metal body into which the glass liner fits, swabbing with solvent should not make much difference, because the sample should never get anywhere near the metal - that's what the glass liner is there for. Having said that I have seen injector bodies so crudded up by repeated injections of filthy samples that the liner was glued into the body !

Be cautious when swabbing because on some GCs there is a chance of getting solvent into the carrier gas lines (on the brand that I suspect that you are using the gas lines connect to the top fitting that you will have screwed off).

Peter

[dirtandwater]

I used to do exactly that, hit the inside of the lower weldment with hexane and scrub with a swab, then rinse - with the bottom seal off.

But about a year ago we started running with the pressfit uniliners (which press-fit directly to the column). I found that not rinsing out the inlet actually worked BETTER than rinsing. Though I do still swab out the top weldment a little with a damp swab.