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- Posts: 2
- Joined: Sun Aug 14, 2016 5:45 pm
I have prepared a standard (system suitability) containing the above solvents at levels of approximately 500-5000 ppm in DMSO.
The chromatography looks great except one problem - my acetic acid peak isn't showing up or is just barely visible in the baseline.
As it's a method transfer I can't vary any of the method parameters, however I will list the parameters here FYI:
manual split injection (5/1 ratio), Helium carrier gas, injection port @ 180 oC, FID @260 oC, DB-624 column (new), temperature program as follows 6 min @ 40 deg oC, 9 minutes @ 100 oC and 10 minutes @ 240 oC with 15 oC/min ramps, 2.5 ml/min flow rate, FID @ 40ml/min H2 and 400 ml/min Air.
I am thinking that the acetic acid is reacting with something in the solvent or in the GC liner, or that my standard is somehow degrading before it gets injected into the GC. Maybe I should try a new batch of DMSO solvent? The DMSO batch I have is new and straight from Aldrich (>99.9% pure confirmed by GC-HS analysis). I have re-prepared my standard numerous times from the same batches of chemicals to no avail.
Anyone have any ideas as to what's going on?
Thanks