GC-FID Detector temperature

[pszor]

Hello.

What really happens if injector temperature is below the boiling point of some compounds? I'm currently using a method that wasn't developed by me that has an injector temperature of 250 ºC and the analytes have boiling points above 300 ºC. I'm using a split injector by the way.

I'm having some problems with repeatability and I think it may have something to do with this, however, i cannot explain it properly.

Thank you

[HPLC chemist]

It is typical to have the injector temperature below the boiling points of the target molecules. The increased oven temperature at 300 degrees (or more) should allow these target molecules to volatize. The detector temperature should be at least 300 degrees.

The problem is most GC's can not go above 300 degrees so your molecules may not volatize, and offer broad and unstable peaks. GC analysis may not be the best means to analyse these samples!

[Jake]

I don't think you're thinking about vapor pressure correctly. It's not that below the BP there's no volatilization. That glass of water on your desk still evaporates at room temp., right?

As mentioned by HPLC Chemist, GC methods are frequently run with the inlet temp. below the boiling point of the analytes.

[KM-USA]

Hello.

What really happens if injector temperature is below the boiling point of some compounds? I'm currently using a method that wasn't developed by me that has an injector temperature of 250 ºC and the analytes have boiling points above 300 ºC. I'm using a split injector by the way.

I'm having some problems with repeatability and I think it may have something to do with this, however, i cannot explain it properly.

Thank you

Raise the inlet temperature to 275C and see if the issue is better/worse/same.

Raise the inlet temperature to 300C and see if the issue is better/worse/same.

Etc.