How is it that carbon tetrachloride shows up on FID?

[osp001]

It's a weak signal, admittedly, but how does it show up at all? CCl4 is not combustible under atmospheric conditions; are the FID conditions (gas mixture + higher temperature) responsible for allowing carbon tet to form ions that the detector reflects the detection of an analyte?

[James_Ball]

I would think that is correct. The FID looks for ionization not simply combustion, if the temperature can knock off even an electron should give a signal. Dichloromethane and Chloroform are also not considered combustible but they give signals, increasing sensitivity with decreasing number of halogens.