Total Organic Carbon Analyser

Louvain-La-Neuve

The determination of dissolved carbon is an essential analytical prerequisite in many agronomic and environmental problems in aqueous media: detection of organic contaminants in soils, control of the decomposition of organic matter from the soil surface, etc.

In these various contexts, the use of a carbon analyzer is particularly judicious when organic substances appear at low concentration levels.

Following a purely operational logic, the TOC L ​​analyzer separates the different forms of carbon by their "purgeability", that is to say the tendency of these substances to leave the solution when they are displaced by a current of gas (sparging technique).

Then each fraction is oxidized in an oven at 680°C and the CO2, product of combustion, is measured by non-dispersive infrared spectroscopy (NDIR). The CO2 is measured by the NDIR detector in the form of a peak. The concentrations are obtained by comparison with a calibration carried out under strict same conditions from potassium hydrogen phthalate. This technique can detect concentrations between 0.1 and 1000 ppm.

 

The nomenclature of dissolved carbon: 

                                                                      

TC : Total Carbon (TIC + TOC)

TIC: Total Inorganic Carbon (CO2, H2CO3, HCO3-, ect)

TOC: Total Organic Carbon (NPOC + POC ou TC - TIC)

NPOC: Non Purgeable Organic Carbon (all organic compounds in natural waters excluding volatiles)

POC: Purgeable Organic Carbon (volatile organic compounds: pesticides, synthetic pollutants, ect)

 

Applications of this method:

  • in the clay fraction (f <2 µm) of soils and in sediments

  • in solutions extracted from acid forest soils and in the liquid phase of hydromorphic soils downstream of agricultural plots

  • in rainwater, rivers, lysimeters in forest ecosystems

  • in soil and river waters in areas of permafrost thawed in the context of global warming

  • measurement of different forms of carbon in river water, waste water, sea water