δ34S measurements on organic materials by continuous flow isotope ratio mass spectrometry
δ34S measurements on organic materials by continuous flow isotope ratio mass spectrometry
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通过连续流同位素比质谱法测量有机材料的 δ34S
DOI：
10.1002/rcm.1939
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
Stephen W. Taylor
中科院分区：
文献类型：
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作者：
Misuk Yun;B. Mayer;Stephen W. Taylor
在连续流模式下，在与同位素比质谱仪耦合的元素分析仪中，通过直接热分解来测量完全干燥的有机样品的硫（S）同位素比（EA-CF-IRMS）。对于13 mg以下、总S含量大于10 μg的有机样品，δ 34 S org a nic值的重现性为′0.4‰或更好。然而，用在线EA-CF-IRMS分析直接测定的有机样品的δ 34 S值比用Parr Bomb氧化法测定的BaSO 4沉淀物的δ 34 S值高0.3 ~ 2.9%。结果表明，有机样品中的结构氧影响SO2的氧同位素比值。因此，有机样品产生的SO2与BaSO 4沉淀物和无机标准物质产生的SO2的18 O/16 O比值不同，导致偏离真实的δ 34 S值，因为32 S16 O 18 O对质量66的贡献。结果表明，有机样品中结构氧的含量以及有机样品与储罐O2氧同位素比值的差异，影响了直接EA CF IRMS分析有机样品后δ 34 S值与真实值的偏差。建议对实测δ 3 4 S值与真实δ 3 4 S值之间的差异进行校正，以获得具有重现性和准确性的有机质S同位素比值。
Sulfur (S) isotope ratios of thoroughly dried organic samples were measured by direct thermal decomposition in an elemental analyzer coupled to an isotope ratio mass spectrometer in continuous flow mode (EA-CF-IRMS). For organic samples of up to 13 mg weight and with total S contents of more than 10 μg, the reproducibility of the δ 3 4 S o r g a n i c values was ′0.4‰ or better. However, the δ 3 4 S values of organic samples measured directly by online EA-CF-IRMS analysis were between 0.3 and 2.9%o higher than those determined on BaSO 4 precipitates produced by Parr Bomb oxidation from the same sample material. Our results suggest that structural oxygen in organic samples influences the oxygen isotope ratios of the SO 2 produced from organic samples. Consequently, SO 2 generated from organic samples appears to have different 1 8 O/ 1 6 O ratios than SO 2 generated from BaSO 4 precipitates and inorganic reference materials, resulting in a deviation from the true δ 3 4 S values because of 3 2 S 1 6 O 1 8 O contributions to mass 66. It was shown that both the amount of structural oxygen in the organic sample, and the difference of the oxygen isotope ratios between organic samples and tank O 2 , influenced the magnitude of the observed deviation from the true δ 3 4 S value after direct EA-CF-IRMS analysis of organic samples. Suggestions are made to correct the difference between measured δ 3 4 S o r g a n i c and true δ 3 4 S values in order to obtain not only reproducible, but also accurate S isotope ratios for organic materials by EA-CF-IRMS.