Contacts :
Scientific correspondent : Nicolas Freslon and Claude Le Milbeau
Brand and model :
Shimadzu TOC-L
Principle :
The dissolved and particulate organic matter is composed of carbon that can be measured with a TOC meter. A distinction is made between total organic carbon (TOC) and dissolved organic carbon (DOC), as well as inorganic carbon (IC) which corresponds to carbonates. The analysis of the sample is done in two steps. In the first step, the sample is acidified with hydrochloric acid to a pH below 2 and purged with O2 to remove the CO2 formed. At this point, the sample contains only dissolved organic carbon. In the next step, a specific volume of sample is injected into a 720°C furnace containing a catalyst (Pt). The carbon is oxidized and released as CO2. The carrier gas carries the CO2 gas stream along a circuit removing water vapor by cooling, then enters an infrared detector, which measures the CO2 concentration allowing, via the calibration curve, to deduce the mass concentration of carbon in the sample.
Objectives :
- Determination of the quantity of organic and inorganic C dissolved.
- Determination of the quantity of N dissolved.
Treated samples :
Water
Pre-treatment :
acidification with H3PO4, filtration at 0.45µm
Results obtained :
Dissolved Organic Carbon, Dissolved Inorganic Carbon, Total Dissolved Carbon and Total Dissolved Nitrogen