Discussion Category: GC-Ion Trap
Rising Baseline after filament change
After replacing a blown filament, and performing the bakeout, the normally flat chromatogram now slowly rises with a big spike up at the end. Does not seem to be a water or leak issue, nor a contamination issue in the trap. Any ideas/help?
Reply byMark C
Check to see if your your GC gas flow rate or temperature is changing suddenly before your acquisition time is up. The programming for temperature or pressure may not match the aquisition time.
Reply byDan Ste.Marie
The answer for the baseline rise depends on what masses you are seeing in the baseline and rise. Look to see if the masses change during the run and which ones are present in the large spike
Dan
Dan Ste.Marie
RJ2 Instrument Services
Erie, PA
www.rj2.biz
Reply bymgeorge
Thank you. The masses are mostly 149 and 178, with 149 being constant.
Reply byDan Ste.Marie
Mass 149 is indicative of phthalate contamination. It is likely coming from your inlet. I would thoroughly clean the inlet with high grade solvent that has not been in a plastic bottle as well as replacing the liner and oring.
Also sonicate the column adapter from the bottom of the inlet.
Dan
Dan Ste.Marie
RJ2 Instrument Services
Erie, PA
www.rj2.biz
Reply bymgeorge
We are using a Tekmar 3100 sample concentrator for sample injections. Would it still be the inlet?
Reply byDan Ste.Marie
Well it doesn't necessarily rule it out however we need to make sure we know where the contamination is coming from. You will need to do a run without utilizing the Purge and trap. Set up your sequence like you normally do but instead of starting the purge and trap simply press the start button on the GC when everything is at ready.
Dan
Dan Ste.Marie
RJ2 Instrument Services
Erie, PA
www.rj2.biz