On the isolation of elemental carbon (EC) for micro-molar 14 C accelerator mass spectrometry: development of a hybrid reference material for 14 C-EC accuracy assurance, and a critical evaluation of the thermal optical kinetic (TOK) EC isolation procedure
On the isolation of elemental carbon (EC) for micro-molar 14 C accelerator mass spectrometry: development of a hybrid reference material for 14 C-EC accuracy assurance, and a critical evaluation of the thermal optical kinetic (TOK) EC isolation procedure
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用于微摩尔 14 C 加速器质谱分析的元素碳 (EC) 分离：开发用于 14 C-EC 精度保证的混合参考材料，以及热光动力学 (TOK) EC 分离程序的严格评估
DOI：
10.5194/acp-5-2833-2005
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发表时间：
2005
影响因子：
6.3
通讯作者：
J. D. Kessler
中科院分区：
文献类型：
--
作者：
L. A. Currie;J. D. Kessler
本文报道的研究的主要目的是开发一种混合参比材料（RM），以测试元素碳（EC）同位素（14 C）形态测量的准确性。这些测量对于定量分析化石和生物质来源的"煤烟"（EC）至关重要，煤烟是对健康、大气能见度和气候有深远影响的火灾示踪剂。先前使用NIST SRM 1649a（城市灰尘）进行的14 C-EC测量质量的研究显示了一系列结果，但由于该天然基质RM的"真相"未知，因此必须依赖测量有效性的同位素-化学一致性证据（PAH中的14 C，EC）（Currie等人，2002年）。为AMS分离的新的混合RM EC级分的组分含有约8%的原始生物质-C;为TOK分离的耐火碳（RC）含有约3%的原始生物质-C。(2)TOK法的初始等温氧化阶段大大减少了伪焦向RC组分的转移，提高了分离能力：（3）混合RM不等于其各部分的总和，基质相互作用引起EC的过早损失，但这种损失可以量化并最小化;（4）三阶段TOK方法提供了在亚微摩尔水平下对碳酸盐进行定量的上级能力，其中"无试剂"地从EC中去除碳酸盐-C-这对于低水平EC-14 C AMS至关重要。
The primary objective of the research reported here has been the development of a hybrid reference mate- rial (RM) to serve as a test of accuracy for elemental carbon (EC) isotopic ( 14 C) speciation measurements. Such measure- ments are vital for the quantitative apportionment of fossil and biomass sources of "soot" (EC), the tracer of fire that has profound effects on health, atmospheric visibility, and climate. Previous studies of 14 C-EC measurement quality, carried out with NIST SRM 1649a (Urban Dust), showed a range of results, but since the "truth" was not known for this natural matrix RM, one had to rely on isotopic-chemical con- sistency evidence ( 14 C in PAH, EC) of measurement validity (Currie et al., 2002). Components of the new Hybrid RM EC fraction isolated for AMS contained about 8% of the orig- inal biomass-C; for TOK, the refractory carbon (RC) isolated contained about 3% of the original biomass-C.; (2) the initial isothermal oxidation stage of the TOK method substantially reduced the transfer of artifact char to the RC fraction, im- proving isolation capabilities; (3) the Hybrid RM was not equal to the sum of its parts, with matrix interactions induc- ing premature loss of EC which, however, could be quantified and minimized; (4) the three-stage TOK method provided a superior capability for carbonate quantification at the sub- micromolar level, with "reagent-free" removal of carbonate- C from EC - essential for low-level EC- 14 C AMS.