Sylva Sean P, Ball Lary, Nelson Robert K, Reddy Christopher M
Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA.
Rapid Commun Mass Spectrom. 2007;21(20):3301-5. doi: 10.1002/rcm.3211.
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.
溴化有机化合物（BOCs）在大气化学、天然产物、地球化学和海洋化学领域备受关注。溴同位素比率（（81）Br和（79）Br；平均（81）Br/（79）Br = 0.97277）在研究这些化合物的来源、传输和归宿方面具有巨大潜力。目前，尚无已发表的方法可用于测定复杂混合物中BOCs的溴同位素含量。为了在化合物特定基础上测量BOCs中稳定溴的比率，我们组装了一套气相色谱/多接收电感耦合等离子体质谱（GC/MCICPMS）系统。背景信号、有机氢形成的氩二聚体以及溶剂峰均未影响结果。对三种溴苯的分析表明，注入0.3 nmol溴时可实现千分之0.3的精密度。对于大于0.3 nmol溴的样品，同位素精密度在散粒噪声极限的3倍以内，这是避免所有其他噪声源可达到的最佳统计精密度。
