Chemical analysis of INDAAF samples (rain, gases, aerosols) are performed at the chemistry service of the Laboratoire d’Aérologie (LAERO) in Toulouse (France). The LAERO’s Chemistry Service analyses more than 7000 samples every year mainly in relation with the ACTRIS-FR (Aerosol, Clouds and Trace Gases Research Infrastructure-France) INDAAF programme but also for the Service National d’Observation (SNO) CLAP (CLimate relevant Aerosol Properties from near surface observations) Pic du Midi site (France) and other collaborative projects.
The service is also dedicated to the preparation of the INDAAF samples (passive gas samplers, aerosol filters pre-treatment of the LAERO and weighing) and performs pH and conductivity measurements on rainwater.
Main equipments :
The Ion Chromatography (IC) technique is based on the separation of ions through a column charged either positively, in the case of an anion separation column, or negatively, in the case of a cation separation column.
IC analyses are mainly performed on three types of INDAAF samples :
- rainwater in order to determine the chemical composition of rainfall (major organic and inorganic ions),
- impregnated filters collected by passive samplers to determine gases concentrations: SO2, NH3, NO2, HNO3 and O3,
- Teflon filters in order to determine the mineral and organic soluble part of aerosols collected on these filters.
The LAERO’s Chemistry Service is equipped with:
- 3 THERMO DIONEX chromatographs : INUVION, AQUION and ICS5000+,
- the Chroméléon THERMO DIONEX acquisition and reprocessing software,
- THERMO DIONEX automatic loaders.
Analytical protocols :
| Devices (Operating Software) | Analysed Species | Columns (4mm) (Duration of analysis) | Suppression | Eluent composition (Flow) |
| DIONEX INUVION +Sample charger ASDV (Chromeleon 7.3.2) | Anions : F–, Cl–, NO2–, NO3–, SO42-, PO43- | Ionic Exchange AG4A-SC + AS4A-SC (9 mn) | Self-suppression DIONEX ADRS 600 | Isocratic mode (1.8 mM Na2CO3/1.7 mM NaHCO3) (2 mL/mn) |
| DIONEX AQUION +Sample charger ASAP (Chromeleon 7.2.10ES) | Cations : Na+, NH4+, K+, Mg2+, Ca2+ | Ionic Exchange CG12A + CS12A (14 mn) | Self-suppression DIONEX CERS 500 | Isocratic mode 20 mM CH3SO3H (MSA) (1 mL/mn) |
| DIONEX ICS 5000+ +Sample charger ASAP (Chromeleon 7.2.10ES) | Acids and anions: Acetic, Propionic, Formal and Oxalic, Cl–, NO3–NO2–, SO42-, PO43- | Ionic Exchange AG11 + AS11 (19 mn) | Self-suppression DIONEX ADRS 600 | Gradient mode KOH 0,7 mM (11 mn) KOH 7 mM (8mn) (1 mL/mn) |
| DIONEX ICS 5000+ +Sample charger ASAP (Chromeleon 7.2.10ES) | Carbonates | Ionic Exclusion ICE-AS1 (15 mn) | Without | Isocratic mode 100 % H2O (1 mL/mn) |
Chromatograms :
Contact : Eric GARDRAT – eric.gardrat@utoulouse.fr
Thermo-optical analysis is a reference method for quantifying organic carbon (OC) and elemental carbon (EC) present in atmospheric particles collected on quartz fiber filters. In Europe, the most widely used and recognized analysis protocol is EUSAAR-2.
Once the system is closed and pressurised, the oven is purged with helium to remove ambient air. A stepped temperature ramp increases the oven temperature to 650°C, thermally desorbing the organic compounds. The OC fraction is oxidized to CO2 into a manganese dioxide (MnO2) oxidising oven and measured using non-dispersive infrared (NDIR). The oven temperature is then reduced to 500 °C.
After this first stage, the carbon remaining on the filter contains elemental carbon (EC) and pyrolyzed carbon formed by the carbonization of high molecular weight organic compounds or natural materials.
The carrier gas is then replaced by a mixture of helium and 2% oxygen. A second temperature ramp is initiated to oxidise remaining EC from the filter that will be detected by NDIR.
The sum of the measured OC and EC corresponds to the total carbon (TC) present in the sample. The optical signal is used to separate what can be assimilated to OC or EC.
Thermogram :
Contact : Maria DIAS ALVES – maria.dias-alves@cnrs.fr
A SARTORIUS MCE3,6P-2S00-M microbalance is specifically dedicated to weigh filters using a special weighing pan. 47mm and 25mm teflon filters are weighed before and after aerosols collection.
Balance specifications :
- MCE3,6P-2S00-M model from SARTORIUS
- Equipped with a METTLER TOLEDO static electricity generator
- Maximum weight : Max1=3100 mg / Max2=2100 mg / Max3=1100 mg
- Resolution based on maximum weight : d1=0,005 mg / d2=0,002 mg / d3=0,001 mg
- Measuring accuracy of ± 5µg
Contact : Eric GARDRAT – eric.gardrat@utoulouse.fr
Other equipments :
– Balance – SARTORIUS Secura 313-15
– Carbon analyser – BRUKER G4 ICARUS
– Conductivity meter – WTW LF 538
– Dissolved carbon analyser – TOC Sievers M9
– Furnace 450°C – Nabertherm
– Heat chamber – MEMMERT
– Microplate reader – Infinite F200 Pro TECAN
– Muffle furnace 1100°C – Thermolyne F48000
– PH-meter – ATI Orion model 350
– Ultrapure water system – Veolia
INDAAF chemical team
GALY-LACAUX Corinne
IR CNRS
Phone: +33 5 61 33 27 06
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Organization:
Laboratoire d’Aérologie (Laero) UMR CNRS/UT n°5560 UMRs IRD n°994, Toulouse, France
Member of:
GARDRAT Eric
IE OMP UPS – Technical manager
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Organization:
Laboratoire d’Aérologie (Laero) UMR CNRS/UT n°5560 UMRs IRD n°994, Toulouse, France
Member of:
DIAS ALVES Maria
TCS CNRS – Chemical analyses
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Organization:
Laboratoire d’Aérologie (Laero) UMR CNRS/UT n°5560 UMRs IRD n°994, Toulouse, France
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LENOIR Océane
AI IRD – Chemical analyses
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Organization:
Laboratoire d’Aérologie (Laero) UMR CNRS/UT n°5560 UMRs IRD n°994, Toulouse, France