PROCESSING OF CO2 SAMPLES COLLECTED USING ZEOLITE MOLECULAR SIEVE FOR 14C ANALYSIS AT THE NERC RADIOCARBON FACILITY (EAST KILBRIDE, UK)
PROCESSING OF CO2 SAMPLES COLLECTED USING ZEOLITE MOLECULAR SIEVE FOR 14C ANALYSIS AT THE NERC RADIOCARBON FACILITY (EAST KILBRIDE, UK)
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DOI：
10.1017/s0033822200057532
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发表时间：
2013-01-01
期刊：
影响因子：
8.3
通讯作者：
Murray, C.
中科院分区：
文献类型：
--
作者：
Garnett, M. H.;Murray, C.
含有沸石分子筛的小柱用于现场收集来自各种环境(例如大气、土壤呼吸、地表水逃逸)的二氧化碳，用于由NERC放射性碳设施进行的加速器质谱仪(AMS)放射性碳分析。以前，在深冷提纯和石墨化之前，通过真空加热从筛子中回收样品二氧化碳。使用了额外的加热和抽空阶段来准备用于下一次样品的色谱盒。我们最近开发了一种替代方法，使用氮气加热和吹扫来从分子筛中去除样品二氧化碳。红外气体分析仪(IRGA)用于连续监测吹扫气体中的二氧化碳含量。同时进行下一次使用的分子筛柱的准备，并使用IRGA读数来验证所有样品的二氧化碳都已从筛子中去除，从而确保将少量的二氧化碳带入下一个样品。我们给出了一套明显不同的C-14和稳定碳同位素组成的标准的结果，我们用这些结果来证实新方法的可靠性。新方法将处理单个样品所需的时间从至少2小时减少到不到40分钟，并将最小样本量减少了50%。
Cartridges containing a zeolite molecular sieve are used for the field collection of CO2 from a variety of environments (e. g. atmosphere, soil respiration, evasion from surface waters) for accelerator mass spectrometry (AMS) radiocarbon analysis by the NERC Radiocarbon Facility. Previously, sample CO2 was recovered from the sieves by heating under vacuum prior to cryogenic purification and graphitization. An additional heating and evacuation stage was used to prepare the cartridge for the next sample. We have recently developed an alternative method using heating and purging with nitrogen gas to remove sample CO2 from the molecular sieve. An infrared gas analyzer (IRGA) is used to continuously monitor CO2 content in the purge gas. The preparation of the molecular sieve cartridge for the next use is performed simultaneously and the IRGA reading is used to verify that all sample CO2 has been removed from the sieve, ensuring insignificant carryover of CO2 into the next sample. We present the results of a suite of standards of distinctly different C-14 and stable-carbon isotope composition, which we used to confirm the reliability of the new procedure. The new method has considerably reduced the time required to process a single sample from at least 2 hr to less than 40 min, and reduced the minimum sample size by 50%.