title: Compound-specific bromine isotope analysis of methyl bromide using gas chromatography hyphenated with inductively coupled plasma multiple-collector mass spectrometry.
abstract: Methyl bromide is the most important natural bromine contributor to stratospheric ozone depletion, yet there are still large uncertainties regarding quantification of its sources and sinks. The stable bromine isotope composition of CH(3)Br is potentially a powerful tool to apportion its sources and to study both its transport and its reactive fate. A novel compound-specific method to measure (81)Br/(79)Br isotope ratios in CH(3)Br using gas chromatography hyphenated with inductively coupled plasma multiple-collector mass spectrometry (GC/MCICPMS) was developed. Sample amounts of >40 ng could be measured with a precision of 0.1‰ (1σ, n = 3). The method results are reproducible over the long term as shown with 36 analyses acquired over 3 months, yielding a standard deviation (1σ) better than 0.4‰. This new method demonstrates for the first time Br isotope ratio determination in gaseous brominated samples. It is three orders of magnitude more sensitive than previously existing isotope ratio mass spectrometry methods for Br isotope determination of other organobromines, thus allowing applications towards ambient atmospheric samples.
authors.affiliation: Department of Applied Environmental Science (ITM), Stockholm University, Stockholm, Sweden.
authors.forename: Axel
authors.initials: A
authors.lastname: Horst
authors.forename: Henry
authors.initials: H
authors.lastname: Holmstrand
authors.forename: Per
authors.initials: P
authors.lastname: Andersson
authors.forename: August
authors.initials: A
authors.lastname: Andersson
authors.forename: Daniel
authors.initials: D
authors.lastname: Carrizo
authors.forename: Brett F
authors.initials: BF
authors.lastname: Thornton
authors.forename: Orjan
authors.initials: O
authors.lastname: Gustafsson