Gas Chromatography Detectors - The Operation of the FID > Page 43

The Operation of the FID

The FID is probably the simplest, easiest and most reliable detectors to operate. Generally the appropriate flow rates for the different gases are given in the detector manual. Hydrogen flows usually range between 20 and 30 ml per min, air flows about 6 times the hydrogen flow e.g. 120 to 200 ml per min. The column flow that can be tolerated is usually about 20-25 ml per min depending on the chosen hydrogen flow. However, if a capillary column is used, the flow rate may be less than 1 ml per min for very small diameter columns. The mobile phase can be any inert gas–helium, nitrogen, argon etc. To some extent the detector is self-cleaning and rarely becomes fouled. However, this depends a little on the substances being analyzed.

Courtesy of Supelco Inc.


1/ Isobutane 2/ n-Butane 3/ Isopentane
4/ n-Pentane 5/ 2,3-Dimethylbutane 6/ 2-Methylpentane
7/ 3-Methylpentane 8/ n-Hexane 9/ 2,4-Dimethylpentane
10/ Benzene 11/ 2-Methylhexane 12/ 3-Methylhexane
13/2,2,4Trimethylpentane 14/ n-Heptane 15/ 2,5-Dimethylhexane
16/ 2,4-Dimethylhexane 17/2,3,4Trimethylpentane 18/ 2,3-Dimethylhexane
19/ 2,3-Dimethylhexane 20/ ethylbenzene 21/ m-Xylene
22/ p-Xylene 23/ o-Xylene 24/ -Me-3-Ethylbenzene
25/ 1,3,5-TriMe-benzene 26/ 1,2,4-TriMe-benzene 27/ 1,2,3-TriMe-benzene
28/ Naphthalene 29/ 2-Methylnaphthalene 30/ 1-Methylnaphthalene
31/ Dimethylnaphthalene

Figure 20. The Analysis of Gasoline