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24, chemin de Borde Rouge -Auzeville - CS52627 31326 Castanet Tolosan cedex - France

Last update: May 2021




Centre Alpin sur les Réseaux Trophiques et Ecosystèmes Lacustre

Chemical lab

The laboratory performs analyzes in the context of environmental monitoring of lakes and rivers, participation in research programs with the various teams at the station. It follows the recommendations of level 1 of INRAE quality assurance and participates every 6 months in inter laboratory aptitude tests.

> Laboratory Analyzes

Equipement :

spectrophometre d'absorption atomique
© INRAE, Atomic absorption spectrophotometer

Atomic absorption spectrophotometer
Elements analyzed: Ca, Mg, Na, K, Fe, Cd, Cu, Zn
The solution is atomized by an air / acetylene flame or an oven, then excited by a lamp of wavelength specific to the element to be analyzed. The quantity of photons absorbed by the atoms is then measured



© INRAE, Ion chromatograph.

Ion chromatograph
Elements analyzed: Cl-, SO42-, NO3-
The elements to be dosed are separated on a column made up of ion exchange resin. Each element appears at a specific time and is quantified using a calibration curve as a function of the area of the peak it forms.


Analyseur de carbone organique et inorganique
© INRAE, Organic and inorganic carbon analyzer


Organic and inorganic carbon analyzer
Elements analyzed: COT, CIT
The addition of a strong acid for inorganic carbon and an oxidant for organic carbon releases CO2 which is measured and quantified using an infrared detector.


Analyseur d'azote total par chimiluminescence

Chemiluminescence total nitrogen analyzer

Chemiluminescence total nitrogen analyzer
Elements analyzed: Ntot
The sample is injected into a quartz catalyst which is pushed into the oven at 1000 ° C. Everything is burnt and oxidized. After dehydration of the gases and addition of ozone, the nitrogen gas is transformed into an unstable molecule (NO *) which releases photons which are measured using a photoelectric cell.


  Analyseur séquentiel

continuous flow


Sequential spectrophotometric analyzer
Element analyzed: SiO2
The sample and the reagents are mixed in order to obtain a greater or lesser coloration of the sample depending on the concentration of the compound to be assayed. The colorimetric measurement of the absorbance is carried out at the required wavelength.


Analyseur élémentaire CHN


CHN elementary analyzer

CHN elementary analyzer
Elements analyzed: Cpart, Npart
The solid sample is placed in a combustion column. The elementary gases thus produced (CO2, NO2, H2O) are separated by chromatography and measured by a catharometric detector (measurement of the thermal conductivity of the gases).


Sprectrophotomètre d'absorption moléculaire

absorption spectrometer


© INRAE, a chlorophyll meter.

Molecular absorption spectrometer
Elements analyzed: NH4 +, PO43-, Ptot, NO2-, chlorophyll a
A color reagent is added to the sample to be analyzed. The absorption is then measured at a specific wavelength of the element to be analyzed. Thanks to the Beer-Lambert law and a calibration curve we determine the concentration of the element in our sample


  Titrateur automatique
© INRAE, Automatic titrator

Automatic titrator
Elements analyzed: TAC, pH, conductivity
The pH and conductivity are measured using specific probes. For the TAC, an acid-base assay is carried out by plotting the curve pH = f (volume of poured HCl). The automation of this titration allows a precise determination of the equivalence point giving us the TAC.


© INRAE, Oxygen titrator

Oxygen titrator
Elements analyzed: O2
During sampling, the oxygen dissolved in the water is fixed with manganese hydroxide. The acidification of the precipitate obtained releases an amount of iodine equivalent to the amount of oxygen in the sample. We then dose the iodine with sodium thiosulfate.