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Strange GCMS chromatography

Question asked by gchaplain Champion on Jan 25, 2018
Latest reply on Feb 15, 2018 by gchaplain

Good Afternoon,


We have an issue that we have been unable to remedy:

This is our internal standard and analyte follows the same pattern. Both splitting and both fronting.

The method is on a diverse matrix ( cannot tell fro leagal reasons but it is not biological and is completely organic) and only happens in this matrix (high boiling), not in low boiling matrices for the same analytes.


The method involves a pulsed splitless injection at 320 degrees (this cannot be changed due to validation requirements)


So far the inlet has been cleaned with methanol and toluene, and the wash vials have been cleaned with toluene, the following have been changed:




gold seal,



split vent line,

split vent trap.


And still the problem persists. There is no leak on the inlet and the MS detects next to no nitrogen or water.


Can anyone have any other suggestions on how to resolve this issue?