Bromine isotope composition (81Br/79Br) of fluids can be measured by two different techniques depending on the sample size and chemical characteristics:
- Gas source mass spectrometry: bromide dissolved in solution must be transformed into CH3Br (gaseous form), which can be analyzed on the mass spectrometer (Delta Plus XP, Delta V). Prior to isotope analysis, Br is separated from Cl (with Cl/Br ratio of ~300 in natural samples). The ratio 81Br/79Br can presently be measured using IRMS with an external analytical precision of 0.1‰ (2SD), for an amount of 3-4 mg of Br.
- MC-ICP-MS : the ratio 81Br/79Br is measured ny MC-ICP-MS with a precision ranginf from 0.1 to 0.5 ‰ (2SD) for low amount of Br (10-50 µg). We are developping a new protocol for bromine chemical extraction using chromatography, allowing us to separate efficiently Br from Cl in highly enriched matrix such as seawater (the ratio Cl/Br of ~300 is lowered to 10).
For further information, please contact Magali Bonifacie or Pascale Louvat