Compound‐specific ⁸¹Br/⁷⁹Br analysis by capillary gas chromatography/multicollector inductively coupled plasma mass spectrometry

Abstract

Brominated organic compounds (BOCs) are of great interest in atmospheric chemistry, natural products, geochemistry, and marine chemistry. The Br isotope ratios ((81)Br and (79)Br; average (81)Br/(79)Br = 0.97277) have significant potential for the study of the source, transport, and fate of these compounds. Currently, there is no published method for determining the Br isotopic content of BOCs in complex mixtures. To measure the ratios of stable Br in BOCs on a compound-specific basis, we assembled a gas chromatography/multicollector inductively coupled plasma mass spectrometry (GC/MCICPMS) system. Background signals, the formation of Ar dimers from organic hydrogen, and the solvent peak did not affect the results. The analysis of three brominated benzenes revealed that 0.3 per thousand precision can be attained when 0.3 nmol of Br are injected. For samples larger than 0.3 nmol Br, the isotopic precision was within a factor of 3 of the shot-noise limit, which is the best possible statistical precision attainable avoiding all other sources of noise.

Assessment of international reference materials for isotope-ratio analysis (IUPAC Technical Report)

“…Sample preparation usually involves precipitation with Ag + solutions, followed by conversion of bromine to methyl bromide, which is measured directly using gas IRMS. As an alternative, (GC-)MC-ICP-MS has also been used for analyzing bromine isotopes [222][223][224]. The range of terrestrial δ…”

Compound‐specific bromine isotope analysis of methyl bromide using gas chromatography hyphenated with inductively coupled plasma multiple‐collector mass spectrometry

“…The technical approaches to this include dual-inlet isotope-ratio mass spectrometry (DIIRMS), continuous-flow isotope-ratio mass spectrometry using gas chromatography as the inlet method (GC/CFIRMS), and gas chromatography inductively-coupled plasma multiple-collector mass spectrometry (GC/MCICPMS). [12,13,[16][17][18] The DI/CF-IRMS methods require about 2-5mg of Br -(DI) and 80mg Br -(CF) for isotope ratio determination whereas GC/MCICPMS only requires about 24ng Br -. [12,16,17] However, the reported precisions so far seem to be somewhat better for the IRMS methods.…”

“…[12,13,[16][17][18] The DI/CF-IRMS methods require about 2-5mg of Br -(DI) and 80mg Br -(CF) for isotope ratio determination whereas GC/MCICPMS only requires about 24ng Br -. [12,16,17] However, the reported precisions so far seem to be somewhat better for the IRMS methods. The smaller sample size requirement makes the GC/ MCICPMS approach more suitable for natural samples, such as methyl bromide in air, than IRMS methods because of the difficulty in collecting sufficiently large samples of trace atmospheric gases.…”

“…[15] Sylva et al hypothesized that enzymatic reactions can cause a fractionation of~4% between the salt and the organic product. [12] The online analysis of bromine isotopes in brominated compounds is still a largely unexplored area of analytical chemistry. The technical approaches to this include dual-inlet isotope-ratio mass spectrometry (DIIRMS), continuous-flow isotope-ratio mass spectrometry using gas chromatography as the inlet method (GC/CFIRMS), and gas chromatography inductively-coupled plasma multiple-collector mass spectrometry (GC/MCICPMS).…”

A High-Volume Cryosampler and Sample Purification System for Bromine Isotope Studies of Methyl Bromide*

“…Previous work has successfully shown fractionations in the bromine isotope system in organobromine substances Holmstrand et al 2010;Sylva et al 2007), and in geologic systems (e.g., Kaufmann et al 1984;Shouakar-Stash et al 2007). Further, it is known that enzymatic dehalogenation reactions impart a particular chlorine KIE on various organochlorine compounds (e.g., Numata et al 2002;Paneth 2003).…”