Compound-specific bromine isotope compositions of one natural and six industrially synthesised organobromine substances

Abstract

Environmental context. Brominated organic compounds of both natural and anthropogenic origin are commonly found in the environment. Bromine has two stable isotopes and the isotopic composition of brominated compounds may vary depending on production pathways and degradation processes. These variations are a result of isotope fractionation effects, when heavy isotopes react slower than lighter isotopes. We apply compound-specific bromine isotope analysis to industrial brominated organic compounds, and one naturally produced analogue, to test the feasibility of the technique to investigate the source and environmental fate of these compounds.Abstract. The stable bromine isotopic composition (d 81 Br) was determined for six industrially synthesised brominated organic compounds (BOCs) and one natural BOC by gas-chromatography multi-collector inductively coupled plasma mass spectrometry (GC-mcICP-MS). The d 81Br compositions of brominated benzenes, phenols (both natural and industrial), anisoles, and naphthalenes were constrained with the standard differential measurement approach using as reference a monobromobenzene sample with an independently determined d Br of four out of six industrial compounds was found to be significantly different from that of the natural sample. These novel results establish the bromine isotopic variability among the industrially produced BOCs in relation to a natural sample.Additional keywords: brominated organic compounds (BOCs), compound-specific isotope analysis (CSIA), gaschromatography multi-collector inductively coupled plasma mass spectrometry (GC-mcICP-MS), pollutants.

Atomic weights of the elements 2011 (IUPAC Technical Report)

“…The minimum and maximum δ 81 Br values of brominated organic compounds (Fig. 2) are -4.3 and +0.2 ‰ relative to SMOB [28]. The minimum and maximum δ 81 Br values of elemental bromine (Fig.…”

“…1), calculated from isotope-ratio measurements of [25], are -0.84 and +0.36 ‰ relative to SMOB, but measurement uncertainties were sufficiently large that isotopic abundance variations were not conclusively demonstrated [25]. The lower bound of the standard atomic weight corresponds to bromine in a brominated benzene reagent [28], and the upper bound corresponds to dissolved bromide in saline groundwater from Siberia [27]. The previous standard atomic-weight value A r (Br) = 79.904(1), recommended by the Commission in 1965 and published in "Atomic weights of the elements 1967" [2], was based on the measurements …”

“…2). The standard atomic weight was determined by combining (1) the best calibrated isotope-ratio measurement of bromine in SRM977 NaBr isotopic reference material [25,26], formerly known as NBS106 [25], (2) the relative isotope-ratio difference between SRM977 and bromide in ocean water [27], and (3) the relative isotope-ratio differences between other materials and ocean-water bromide [2,28]. Bromide in ocean water is isotopically homogeneous and serves as the international measurement standard for bromine [26], standard mean ocean bromide (SMOB).…”

“…Bromide in ocean water is isotopically homogeneous and serves as the international measurement standard for bromine [26], standard mean ocean bromide (SMOB). Bromine relative isotope-ratio differences, also called bromine isotope delta values, have been reported with the symbol δ 81 Br [26][27][28] and are defined by the relation [20] where N( 81 Br) P and N( 79 Br) P are the numbers of atoms of the two isotopes 81 Br and 79 Br in material P and equivalent parameters follow for bromine in SMOB. The minimum and maximum δ 81 Br values of saline waters and salt deposits (Fig.…”

Stable bromine isotopic composition of methyl bromide released from plant matter

“…It accounts for both low temperature emissions from dead and senescent plant material (Derendorp et al, 2012) and, together with the lignin methoxy groups, for biomass burning (Andreae and Merlet, 2001;van der Werf et al, 2006). For methyl chloride ~20-25% of the estimated total budget might come from biomass burning and a similar amount from senescent plants and plant litter (Keppler et al, 2005;Saito and Yokouchi, 2008).…”