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- Posts: 4
- Joined: Mon Feb 20, 2023 7:42 am
- Location: Australia
Hi All,
Basically what is in the title is my problem.
We are running Geosmin/MIB analysis on a shimadzu GCMS with SPME. I am not at work right now, and can't remember the specific model of GCMS we use, i believe its a QP2010.
There are a few issues, mainly a drop in surrogate/IS response (we run with IPMP) and an increase in noise along the baseline as the injection progresses. For example the noise in my windows for IPMP and 2-MIB will be fine (2-MIB eluting at 10 minutes), but once the window opens for Geosmin the baseline is a mess. I can see the quantifier ion well enough, but my 1st and 2nd reference ions are struggling.
This problem began when I removed an old column (DB-5MS) and replaced it with a new DB-5MS-UI column, both with the exact same dimensions only difference being the UI on the newly installed column.
Attempts at trouble shooting:
- clean ion source and lens stack installed.
- new filaments in both positions.
- new merlin septa.
- trimming the column on both ends twice, with new ferrules and nuts each time.
- liner/o-ring and SPME fiber is changed weekly or when we start a new sequence.
Any help would be greatly appreciated, I have exhausted most of my resources at work to fix this with the senior analysts, shimadzu tech suggested lens stack was the issue but it hasn't proven to help after the installation of a clean one.
Basically what is in the title is my problem.
We are running Geosmin/MIB analysis on a shimadzu GCMS with SPME. I am not at work right now, and can't remember the specific model of GCMS we use, i believe its a QP2010.
There are a few issues, mainly a drop in surrogate/IS response (we run with IPMP) and an increase in noise along the baseline as the injection progresses. For example the noise in my windows for IPMP and 2-MIB will be fine (2-MIB eluting at 10 minutes), but once the window opens for Geosmin the baseline is a mess. I can see the quantifier ion well enough, but my 1st and 2nd reference ions are struggling.
This problem began when I removed an old column (DB-5MS) and replaced it with a new DB-5MS-UI column, both with the exact same dimensions only difference being the UI on the newly installed column.
Attempts at trouble shooting:
- clean ion source and lens stack installed.
- new filaments in both positions.
- new merlin septa.
- trimming the column on both ends twice, with new ferrules and nuts each time.
- liner/o-ring and SPME fiber is changed weekly or when we start a new sequence.
Any help would be greatly appreciated, I have exhausted most of my resources at work to fix this with the senior analysts, shimadzu tech suggested lens stack was the issue but it hasn't proven to help after the installation of a clean one.
