A post column oxidation-reduction reactor is a chemical reactor that performs derivatization to improve the measurement of organic molecules. It is used in gas chromatography (GC), after the column, and before a flame ionization detector (FID), to make the detector response uniform for all organic molecules.
The reactor converts the carbon atoms of organic molecules in GC column effluents into methane before reaching the FID. The resulting detector response is uniform on a per-carbon basis and avoids the need for response factors and calibration standards for each molecule. It can improve the response of the FID to many molecules with poor/low response including carbon monoxide (CO), carbon dioxide (CO), hydrogen cyanide (HCN), formamide (CHNO), formaldehyde (CHO) and formic acid (CHO), because these molecules are converted to methane.