SO HYBAM / Technics / Laboratory analysis

Laboratory analysis

 

The analysis are performed:

  • At LAGEQ-UnB, Brasília
    • major anions ( F, Cl, NO3, PO4, SO4) are determined using ion chromatography,
    • Alkalinity is determined by titrimetry using an automated titrimeter (Schott).
  • At GET (ex LMTG), Toulouse
    • Ca, Mg, Na, K, Fe, Si, Al, Mn are determined by ICP-OES,
    • DOC is measured by HTCO (High Temperature Catalytic Oxydation) method,
    • trace elements are determined using ICP-MS (Ti, V, Cr, Mn, Co, Ni, Cu, Zn, As, Rb, Sr, Zr, Mo, Cd, Sn, Ba, Pb, U, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu),
    • Sr Isotope analysis are performed by mass spectrometry (TIMS) after separation on Sr Spec resin.

The procedures are detailed in appendix. .

The trace elements samples were taken twice during the installation campaigns in order to duplicate the analysis and determinate the results accuracy. A sample used to isotope determination was taken during every station starting. An aliquot is made from the suspended material filtered solution. Sr and Pb isotopes analysis are performed by mass spectrometry (TIMS) at LMTG. δ2H and δ18O are determined as part of an agreement signed with IAEA (Viena).

Further details on the analysis methods

Major cations determination

They are determined by inductively coupled plasma-optical emission spectrometry on a spectrometer IRIS Intrepid II XSP, Thermo Electron Corp.

The wavelengths used are, in nm :

Si : 251,6 Al : 308,2
Ca : 317,9 Mg : 285,2
Na : 589,5 K : 766,4
Mn : 257,6 Fe : 259,9

 

All measurements are performed with radial viewing and the calibrations are performed using standards prepared with 0,5, 2,5, 10 and 25 mg L-1. A 1100 watt RF generator, operated at 27.12 MHz, is used.

The calibration accuracy is controlled by using a reference material SLRS4.

Anions determination

A ion chromatograph system is used (Dionex, ICS 90), equipped with an AG14A guard column, an AS14A column and a suppressor column. Operating parameters: 1 ml.min-1 , 1900 to 2200 psi.

Eluent: NaHCO3 1 mM / Na2CO3 3.5 mM.

Regenerant : H2SO4 0,05N.

The standards are prepared from standard wash solutions (1000ppm) with intermediate standard solutions (100ppm).

Used standard ranges (mg/l)
Element Standard 1 Standard 2 Standard 3 Standard 4
F 0,5 1,0 2,5 5,0
Cl 1,0 2,5 5,0 10,0
NO3 0,5 1,0 2,5 5,0
PO4 0,5 1,0 2,5 5,0
SO4 1,0 5,0 10,0 15,0

 

The calibration accuracy is controlled by using ION-915 and BMOOS standards.

Dissolved organic carbon determination.

DOC is measured by high temperature catalytic oxidation method (HTCO) using a Shimazu TOC 5000 analyzer. With this method, a sample is passed through a platinum catalyst (Pt) at high temperatures (680°C) and converted to CO2 gas. DOC is broken down in CO2. The combustion product is measured with an infrared detector. The detected CO2 generates a pick which area is proportional to the carbon content.

Depending on the sample concentration, two ranges are used: 1, 2 and 5ppm or 2, 5 and 10ppm. The standards are prepared from a Potassium Biphtalate standard wash solution (1000ppm).

To valid the samples, certified reference material BMOOS is used.