Chromatography Forum

Hi All

We were interested in the change in the intensity of the analytical signal at different interface temperatures.
A standard solution of alkanes was prepared for the experiment. Testing interface was carried out in the range of 200-300 °C. Injector temperature - 250 °C. The furnace temperature ramp was set at a rate of 10 °C min from 50 °C to 220 °C. Ion source temperature - 200 °C. Perkin Elmer Clarus 600T.

Finally, it was found that at higher temperatures, the intensity of the analytical signal decreases. The area of the peaks is also decreasing. We noticed that the retention time is slightly increasing

Could it be memory effects? Сan it affect the fact that the column has a temperature lower than the connecting line? Is it possible that due to the fact that helium heats up and expands at higher temperatures, we observe a similar image?

If you know any literature on this topic, then please share it. Thanks for the answer

As said one forensic expert:
"Chromatography is not science, it is kitchen - just recipes".

The behavior you described is likely introduced by instrument but not common effect.
Do your GC-MS interface is direct or has a vent?
IMO - try examine the interface construction, is not it is just leak at higher temperatures?

If the column passes through the interface, the higher temperature can increase the amount of column bleed which would make the peaks on the full scan chromatogram look smaller due to the baseline being elevated.

Also the flow will drop slightly due to increased viscosity of the carrier at higher temperatures, but that should not be a large affect at all.