Chromatography Forum

Earlier you mentioned dirt in the liner, which presumably came from earlier samples (it cannot have come from blanks and solvent injections). This suggests some history - what samples and how many have been run through the system previously ?

Peter

thats hard to tell but since the last liner change, roughly 300 samples (headspace, t-BME extracts from food samples, some standards,...)

I rinsed now the injector with acetone and n-hexane and backout once more 500°C for 1 h (with liner inside, and septa, as suggested by ATAS GL technician)

300 samples is a lot between liner changes. The headspace samples will not have deposited crud in the inlet, but if they were in an aqueuos matrix the water vapour might have hydrolysed the column phase to some extent. Certainly food extracts will crud up an inlet in short order, and there is a good chance that some heavy muck is sitting on the first couple of metres of the column.

Do you have replacement inlet liners and'or a spare column that you can test ?

Peter

Headspace samples were in aqueous matrix there was vor sure som water vapour.
Using the liner for so many injections was not a problem till I went for splitless injections.
Then i changed the liner, and interestingly the background got worse.

I also cut of roughly 30-40 cm of the column.

I have a spare column as well as some spare liners.

Is it possible to clean a liner.
I actually have never tried it. Could i just rins it with n-Hexane or Aceton or some other organic solvent?

After cleaning injector with solvent
baking at 500°C for 1 h
conditioning of the column (180min at 320°C)
and several empty runs (just temp program, no injection)


i am not totaly satisfied but for now i will go to the next step
injection of pure solvent
I will keep you apprised

Thanks for all your help

Have you checked the tip of the injection-needle?
If there is even the smallest hook it will rip your septum and small septum particles will end up in your liner causing a lot of peaks.

Thanks for the advice

I checkt the needles and it seems they have a ruther sharp edge if i slide them over a paper
i get small shallow cuts.

I then check the other 10µL needle and this has the same sharp edge.
So fare I am not very happy with my needle brand again a needle problem that cost me a lot of time.

I adviced my supplier to get me a Needle that does not have this.

hopefully this will resolve some contamination issues

Hi,

old thread but was the problem solved? If yes, how?
Thanks and BG