GC-MS Baseline Increase

Please upload the acqmeth.txt file that is located in your run method's windows subdirectory along with a run chromatogram.   Single quad or triple quad?   If it's a triple quad do you have a few time segments?  If it's a single quad do you have any scan/sim time segments?

Dear Mr Paul Salverda

Additional information:

- GCMS Single quad (Thermo Scientific)

- Column: DB-5MS Agilent

- Liner 5190-2295 Agilent

- Oven programe

- Mass SIM: ionsource 230 oC, EI.

- Chromatogram:

The ions you are scanning for changes so if the baseline has more or less of those ions due to background or sample matrix it will jump up and down over the time ranges. 

This is standard. Used to be fine, I had a problem about a month ago

This is a thermo MS using their software.  If this was an Agilent system I would try looking at the chromatogram in MassHunter Qualitative Analysis and plot each of the SIM ions in each group to see if it is one or more that have higher baseline.  I would also try running in SIM/Scan mode so that Scan data could also be evaluated to see what else is going on by time segment.  Since some segments appear normal, it is probably related to a method setpoint.