Basics of GC

The detector

It generates a signal proportional to the amount of analyte leaving the column and passing through the detector cell.

Diagram of a flame ionization detector. The burner in the center, with the capillary column underneath, and on its right the air and hydrogen inlets. Above the burner is the flame. The flame is surrounded by a cylinder representing the collecting electrode.

Flame ionization detector (FID)

Response coefficient depends on the chemical structure of the compound: this must be taken into account when calibrating by internal standard.

Mass Spectrometer

It generates a mass spectrum characteristic of the chemical structure of the compounds. This makes it an informative detector for identifying analytes. Diagram of a magnetic sector mass spectrometer. At the beginning the chamber where the molecules are introduced. They pass through a vacuum, then a flow of electrons, then the repulsor and finally a gas pedal. These elements constitute the ionization chamber. Then the molecules pass through the analyzer, through the collector and finally to the recorder.

Transcript : French English