Headspace Problem

[Peter Apps]

No the steam clean didnt make any difference...

I ran only two air and a clean water sample.
No standard

In every sample there was a 0,08pA Ethanol Peak.

Greetings

No the steam clean didnt make any difference...

I ran only two air and a clean water sample.
No standard

In every sample there was a 0,08pA Ethanol Peak.

Greetings

If you are still getting the same sized peak after a steam clean it points to persistent system contamination rather than just carryover from recent samples, and it looks likely that it is somewhere not affected by the steam clean, so the inlet is looking more and more suspect.

Peter

[ZlausD]

I think it was the liner or the septa.....

I changed the liner to a broader one and the septa -> result was that the solvent peaks are smaller.

Carryover is now at 0,1 %

Gettin better


Thanks guys

[Peter Apps]

Good news !

Try increasing the septum purge flow. Also a double gooseneck liner might help even more.

Peter

[ZlausD]

To increase the septum purge flow dont i have to run in splitless mode?

Double goose neck liner is ordered

i try a single goose neck that i found somwhere in my company

[Peter Apps]

To increase the septum purge flow dont i have to run in splitless mode?

No, or at least not on any GC I have ever used.

Peter

[Bigbear]

If you inject MeOH directly into the GC,and see only it, then you can rule out the injector as the caryover source.

[ZlausD]

I injected pure MeOH in the injector and there only was the MeOH Peak.....

....so the problem is the Headspace sampler.....

Thanks Bigbear

[amazhad]

To increase the septum purge flow dont i have to run in splitless mode?

No, or at least not on any GC I have ever used.

Peter

The GC is a 6890, there is no option to increase the septum purge flow. The 7890 series allows the septum purge to be changed.

A 2 mm straight through liner without glass wool should be all you need (Agilent part# 5190-6168).

[ZlausD]

Thanks guys I´ll order the liner and test it