188.8.131.52.2. Oven temperature ramp
The oven temperature affects how compounds interact with the stationary phase (column coating). Generally, more volatile compounds with lower column coating affinities pass through the column before less volatile compounds with higher affinities for the column coating. Choosing the right temperature regime is important for GC analysis. The points below are basic guidelines which should the selection of the right temperature conditions for any given analysis.
- A standard method for solvent desorption starts at 35°C, holds for 2 minutes at this temperature, and then increases at 10°C per minute to 230°C, followed by a final temperature hold for 5 minutes.
- To separate highly volatile compounds, start the oven lower (30°C) and hold temperature for 5 minutes before starting the temperature ramp. A slower ramp (5°C per minute to 75°C, followed by 10°C per minute to 230°C) can also help to separate highly volatile compounds that would otherwise elute together early in the run.
- For thermal desorption, start oven temperatures at 30°C with similar hold and ramp parameters.
- To separate compounds with lower volatility, a higher maximum oven temperature with a longer final temperature hold is required. Increase the maximum oven temperature to 280°C and then hold the maximum temperature for 10 minutes.