Chemiluminescence is the emission of light by molecules, induced by a chemical reaction. A chemiluminescence detector (CLD) is a highly specific GC detector.

Major components of chemiluminiscence detector

For specific sulphur detection the initial reaction to form the SO-radical is carried out by combustion in a catalytic conversion oven or a hydrogen diffusion flame. Alternatively the flame plasma from a normal FID can be sampled by a suitable probe. Next, a secondary reaction is performed with ozone in an evacuated chamber. The general mechanism for specific sulphur detection is as follows:

The detection of N-containing species involves a similar suite of reactions.

Sulphur detection by chemiluminescence offers a considerable advantage over the use of the FPD in that the response is equimolar for different compounds, and is intrinsically linear, with a linear response range of >10³ and detection limits of 10^-12-10^-13 g S/s.

Sulfur chemiluminescence detector

The most important applications for CLD's are for N or S-containing compounds in concentrations as low as the picogram level.

High boiling oil fraction