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SCD
Posted: Mon Nov 16, 2009 7:26 pm
by lynoguchi
I have a SCD equipment with a chromatograph.
But, I have a problem, in the first injection, the peaks appears normally, but from the second, the peaks desappear.
Do you have a theory about this?
Thanks
Posted: Tue Nov 17, 2009 6:15 pm
by aldehyde
what are the peaks?
Posted: Wed Nov 18, 2009 3:50 pm
by lynoguchi
Sulfur compounds, like H2S, COS, methylmercaptane.
Posted: Wed Nov 18, 2009 4:26 pm
by aldehyde
What are you using to inject sample? A gas tight syringe, valves, what kind of inlet? What carrier gas?
Posted: Wed Nov 18, 2009 6:28 pm
by lynoguchi
I´m using a GSV, but before the valve, I'm using a inox tubing.
The carrier is Helium, but I only pass the gas sample through the tubing and valve, without carrier.
Posted: Wed Nov 18, 2009 6:33 pm
by AICMM
lynoguchi,
How old is your SCD? The older SCD's had a problem of reactive furnace tubes that would basically start to gobble up sulfur compounds from the very start.
Best regards.
Posted: Wed Nov 18, 2009 6:41 pm
by lynoguchi
The SCD is new. It was installed 2 months ago.
But I think the problem is the ceramic tube for pyro.
Maybe I need to change it?
Posted: Thu Nov 19, 2009 7:39 pm
by AICMM
lynoguchi,
Based on my limited knowledge of SCD, I would suggest replacing the tube as the starting point. Unfortunately, I do not have hands on with this detector although I hope that is about to change.
Best regards.