A simple distillation method to extract bromine from natural water and salt samples for isotope analysis by multi‐collector inductively coupled plasma mass spectrometry

Abstract

Unlike other Br extraction methods based on oxidation, the distillation method presented here does not use any metallic ion for redox reactions that could contaminate the mass spectrometer. It is efficient in separating Br from samples with low Br/Cl ratios. The method ensures reproducible recovery yields and a long-term reproducibility of ±0.11‰ (1 standard deviation). The distillation method was successfully applied to samples with low Br/Cl ratios and low Br amounts (down to 20 μg).

Bromine Isotope Variations in Magmatic and Hydrothermal Sodalite and Tugtupite and the Estimation of Br Isotope Fractionation between Melt and Sodalite

“…Sodalite and tugtupite are both soluble in diluted nitric acid. For that reason, the technique developed by Eggenkamp and Louvat [5] was chosen to extract Br from the samples. An amount of mineral separate sufficient to collect enough Br for isotope analysis was ground in a mortar and subsequently weighed.…”

“…The ground mineral was put in a 50-mL two-neck round-bottom flask to which 8 mL Milli-Q water (18.2 MΩ) and 2 mL concentrated nitric acid was added, as well as a few Teflon anti bumping granules to facilitate gentle boiling. The distillation set-up was assembled as described before [5] and consisted of a bridge and a 5-mL plastic vial containing 1 mL of a 0.5 M NH 3 solution as ammonium trap. The sample was gently heated using a Teclu-burner until boiling.…”

“…Our knowledge is currently mostly restricted to aqueous systems and salt deposits and to some environmentally relevant organobromine systems that are Br-rich, and where Br can easily be extracted in sufficient quantities for isotope analyses [2]. Depending on the analytical technique either about 1 mg (isotope ratio mass spectrometry (IRMS) [1,3]) or 25 µg (multi collector inductively coupled plasma mass spectrometry (MC-ICP-MS) [4,5]) of Br is necessary for a reliable measurement. The large amount of Br necessary for isotope analysis has, until now, prevented the measurement of Br isotopes in rock samples.…”

“…The Br contents in these minerals vary between 25 and 150 µg/g [21]. Thus, 0.15 to 1 g of mineral separate is sufficient for Br isotope analysis [5], so that these minerals are a valid target for the determination of Br isotopes in magmatic rocks and hydrothermal systems.…”