[mandytan]

I conducted a Gas Chromatography experiment using Flame Ionisation Detector (FID).
1)Blank
2) Standard
3) Sample
4)Blank
5)Standard
The above was injected into the system.

In 2)Standard chromatogram,a sharp, thin peak was observed between the 2 principal peaks. This peak had area count of less than 100.
This sharp peak was also seen in 4)Blank.

However, this sharp peak was not present in 5)Standard chromatogram.
Can you suggest a reason for this sharp spike/peak seen in 2) and 4)?

[Andy TB]

Possibly a noise spike. Give the FID a clean.

[Stepan]

Also check H2/N2/Air ratio

[Pradeep]

My sugession is to repeat the experiment. If those spikes are not repeatedly appeared in the same way once you have got, this should be a noise.

[mandytan]

Hi,
How would the H2/N2/Air ratio affect the resultant chromatogram?
How would you suggest I clean the detector?

[Stepan]

To clean, take it apart, soak in methanol, remove the tar and build-ups. clean stainless steel surfaces with wire brush to remove oxides. Try not to touch an ignition filament.

Gas ratio affects flame stability. On my HP GC FID I see spikes then flame is too reach on hydrogen.