No peak/missing peaks in Head space GC injections using 7697A sampler

Hello mkaadan ,

Did you check if the respective vial caps were actually punctured? If you haven't, monitor when this happens next and see if they were punctured.

Are you using Agilent vials and caps? 

I would assume at this point it is not HW related, not at that "low" of a failure rate (2 out of 50 samples), unless, those 2 samples are somehow different than the other 48.

Improper vial crimping is potentially a source of problem too. As far as the SW is concerned, you would need to see what the errors are in the logs.

Hello,

First, thanks for the response. regarding to your questions:

the respective vials were punctured. and I can also add that sometimes re-injection from these same vial, produced a "good" chromatogram and all peaks were seen.

We used La-Pha-Pack GC vials.

For us, a failure rate of 2 of 50 injections is VERY HIGH, espicialy when it is a formal work and investigation report could be needed due to failure.

We have to resolve this issue .

Thanks,

Maher K.

Hello mkaadan ,

What I meant by a "low" failure rate (notice the quotation marks), is that it is likely not an indication of a leak, as that would result in a lot more samples failing, or potentially all of them. By no means I wanted to minimize the problem you are seeing.

If you suspect a leak, you can always do a leak test using the procedure at the link below. If it fails at any step, you have an indication next to that step as what the problem might be.

7697A Headspace Sampler - Leak Testing the Headspace Sampler (agilent.com)

In terms of the puncture, while I take your word for it, next time it happens please take a close look. Sometimes it might look like they were punctured but upon very close inspection it's not the case. It's possible at the second usage of the vial it actually got punctured.

What I suggest is to check appropriate vial crimping, and if you have not tried it yet, use Agilent consumables (vials, caps), and an Agilent crimper, if you don't have one already.

Please share your results on the leak test.

Hello mkaadan ,

What I meant by a "low" failure rate (notice the quotation marks), is that it is likely not an indication of a leak, as that would result in a lot more samples failing, or potentially all of them. By no means I wanted to minimize the problem you are seeing.

If you suspect a leak, you can always do a leak test using the procedure at the link below. If it fails at any step, you have an indication next to that step as what the problem might be.

7697A Headspace Sampler - Leak Testing the Headspace Sampler (agilent.com)

In terms of the puncture, while I take your word for it, next time it happens please take a close look. Sometimes it might look like they were punctured but upon very close inspection it's not the case. It's possible at the second usage of the vial it actually got punctured.

What I suggest is to check appropriate vial crimping, and if you have not tried it yet, use Agilent consumables (vials, caps), and an Agilent crimper, if you don't have one already.

Please share your results on the leak test.

Hello,

Can we use Agilent screw top vials (Part No: 5188-2753) and Agilent screw caps (Part No: 5188-2759) for 7697A autosampler?

Regards,

Maher K.

We have a Supplies Ordering Guide for the headspace sampler, that lists all recommended consumables. The part numbers you mentioned might also work, we prefer capped vials as the crimpers use the same torque for all caps; screwing a cap on can differ in how strong the sealing is.

Regards,

Norbert