Chromatography Forum

This is my first day exploring the forum and there is a lot of great information regarding certain problems. My problem is that after cool down the temperature fluctuates ~5-10 degrees within seconds and continues to do so until the next injection. This hasn't effected the retention times or caused any further problems but trying to prevent future problems. Any information would be greatly appreciated. Thanks in advance.

Just some questions:

- What GC are you using?
- At what temperature you're running your FID? (I guess the temperature of your FID is changing)

My best guess would be that water condenses on top of your FID and drops onto the temperature probe, thus cooling it. Older DANI boxes are very prone to that problem (DANI released glaswool-packed insulators for their early FID as a remedy).

- What GC are you using?
- At what temperature you're running your FID? (I guess the temperature of your FID is changing)


- SRI 8610 is the name of the GC
- Our runs are set for 56-201C

The only fluctuations occur when it cools down. The initial temperature(pre-problem) was 56 (+/-) 1 degree, but now fluctuates 5-10 degrees. I hope this information helps.

JMat,
HbJ thinks that your FID temperature is unstable - whereas are you saying that the initial oven temperature is unstable.
How long is your equilibration time before injection?
What temperature is your lab at?
Unfortunately I dont know about the GC that you use.
WK

JMat,

1) Does your detector actually have a heater? The 8610 I have does not, it simply gets its heat from the oven and the flame. POS.

2) If you do have a heater, and it is set to 56, it is way too cool. Set it to at least 20 C hotter than your oven profile max temperature.

Best regards

JMat,

As WK noted, I presume that you are talking about your oven temperature?

Regards,

Ralph

I apologize for the confusion, it is the initial 'column 1 oven temperature'. I should have mentioned that when I first submitted my question.

WK-
-Our lab temperature is recorded and maintained everyday and there are no fluctuations in the actual lab temp.

-Well there isn't a set equilibrium before injection because the temperature fluctuates so much, but the time in between injections is anywhere from 1minute-10minutes depending on how hectic things are around the lab.

-Thank you all for your time and info thus far. If there is any other info needed to aid me please let me know.

JMat

According to what yo describe I feel as if the heating element of the oven and control does not work properly .

Did you contact the supplier already?He should be able to assist you on this problem, which is according to me a technical one

information for this GC can be found on the internet by the way )

regards

philippe

Phillippe,

-I'm well aware I can contact the supplier and ask for assistance which I tried and was placed on hold. I don't have the time as of now to sit on hold for something that could be a minor problem that I can fix on my own time. The GC is working fine. What I'm doing is more of a preventive maintanance. I would like to try and fix this on my own before I reserve a day to sit on the phone and talk to someone for assistance. Thanks.

-JMat

Hi,

I am just wondering if you might have an oven vent door that is sticking slightly?

http://www.quadrexcorp.com/new/sri/srispecs.htm

Regards,

Ralph