By Amy on Tuesday, May 11, 2004 - 06:56 am:
I have a 5890 GC with an FID. I used to run with pretty good sensitity and little baseline rise. The machine was recently down for 3 weeks, during which time the detector was taken out and cleaned and flows where checked. I have checked for leaks, there are none. I have a new septum. Now my sensitivity is about 1/10th of what it was and my baseline rise at the is about 5x what it was. I am running TPH on this machine. Help!
By Anonymous on Tuesday, May 11, 2004 - 07:21 am:
Check your column a the detector side !
The column could be too deep into the jet or too far away.
Check the end of the column if it appears to be burn it could be that.
Good luck
By Amy on Wednesday, May 12, 2004 - 07:07 am:
I checked the column on the detector side and the depth seems okay. I am using an MXT-5 column. My temp program is 60 for 1.5 min then 25/min to 300 for 5 min. My inlet temp is 250 and detector temp is 280.
Thanks,
Amy
By Anonymous on Wednesday, May 12, 2004 - 07:16 am:
The sensitivity decreased when the detector was taken out and cleaned. The most likely cause of the problem is something done (or not done) during the process of taking the detector apart, cleaning, and re-assembly. Check everything, including the ferrule at the capillary adaptor. was the service done by a service technician or by someone in the lab? If someone outside the company was paid to do the service they should come back and recheck the detector at no charge.
By 54u0 on Tuesday, July 13, 2004 - 02:16 am:
Please check your gas source. Confirm if there is no leakage including your cylinder valve. Air impurities may lead to this kind of sensitivity loss.
By jeffo on Wednesday, July 21, 2004 - 01:28 pm:
I also run a 5890 FID and do TPH analysis. Try baking out the column and running numerous Mecl2 blanks. This should stabilize your baseline.
jeff