Study on the Optimal Reaction Temperature and Sampling Weight for Measurement of Carbon and Nitrogen Isotope Ratio by Elemental Analyzer-Isotope Ratio Mass Spectrometer
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摘要: 沉积有机质的碳氮稳定同位素值是进行古气候、古环境及生态系统研究不可或缺的主要研究手段，目前碳氮同位素主要利用元素分析仪-同位素比值质谱(EA-IRMS)系统来测定。EA-IRMS测定过程中的反应温度及样品进样量直接影响反应物在测试中的燃烧程度，从而影响测试数据的精度。本文利用EA-IRMS技术，以标准样品为参考，在不同转化温度下测试碳氮同位素值，研究保证测试精度的最佳反应温度条件；同时，通过分析不同含氮量样品的检测限，明确了样品含氮量与最低检测限之间的关系，确定了精确测定氮同位素值的最低进样量。结果表明：反应温度对测试精度有显著影响，在碳同位素测定时，将反应温度设定为900℃或以上时测试精度均能达到±0.2‰；氮同位素测定时，反应温度须设定为950℃时测试精度才能达到±0.3‰。实验得出样品含氮量与检测限之间的线性相关性为R2=0.873，开展氮同位素测定时可根据此关系来判断和控制进样量。
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关键词:
- 元素分析仪-同位素比值质谱 /
- 碳氮同位素比值 /
- 反应温度 /
- 检测限
Abstract: Carbon and nitrogen isotopes are essential tools to study paleoclimate, palaeoenvironment, and ecosystem. At present, carbon and nitrogen isotopes are commonly determined by Elemental Analyzer-Isotope Ratio Mass Spectrometer (EA-IRMS). Reaction temperature and sampling weight directly affect the burning of samples, and thus affect analytical precision. Using EA-IRMS technology and taking standard samples as references, the carbon and nitrogen isotope values were determined at different conversion temperatures to study the optimum reaction temperature, in order to ensure the accuracy of the analysis presented in this paper. At the same time, by analyzing the detection limits of samples with different nitrogen contents, the relationship between the nitrogen content of the sample and the lowest detection limit was determined and thus the lowest quantity of samples for accurate determination of nitrogen isotopes were also defined. The results show that reaction temperature has a significant effect on analytical precision. Analytical precision of carbon isotope is less than ±0.2‰ when the reaction temperature is either 900℃ or higher than 900℃, but the precision of nitrogen isotope can reach ±0.3‰ only when the reaction temperature is no lower than 950℃. The linear relationship between nitrogen content and detection limit was expressed as R2=0.873 according to the data. According to this relationship, the sample introduction quantity can be determined and controlled when analyzing nitrogen isotope. -
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表 1 样品详细信息
Table 1. Details of the sample
样品名称 产地 纯度(%) 化学式 碳氮含量(%) 样品类型 同位素参考值(‰) C N C N 尿素 德国 ＞99.5 CN2H4O 20.0 46.7 STD -28.25±0.24 -0.36±0.25 磺胺 德国 ＞99.5 C6H8N2O2S 52.9 13.7 STD -26.56 -1.23 小麦粉 英国 - - - - STD -27.21±0.13 2.85±0.17 咔唑 中国 ＞98.0 C12H9N 86.2 8.4 S - - 2, 7-二甲基咔唑 中国 ＞98.0 C14H13N 86.2 7.2 S - - 甘氨酸 中国 ＞98.5 C2H5NO2 32.0 18.7 S - - 苏氨酸 中国 ＞99.1 C4H9NO3 40.3 11.8 S - - 注：STD代表元素分析标准样品；S代表被测样品(碳、氮同位素值未知)。 
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表 2 样品称样量
Table 2. The sampling weight
测试次数 称样量(μg) 磺胺 小麦粉 咔唑 2, 7二甲基咔唑 甘氨酸 苏氨酸 1 0.141 0.295 0.097 0.070 0.130 0.056 2 0.051 0.265 0.038 0.057 0.015 0.021 3 0.028 0.161 0.063 0.041 0.043 0.054 4 0.012 0.251 0.073 0.057 0.096 0.018 5 0.054 0.206 0.042 0.043 0.056 0.045 6 0.051 0.173 0.044 0.031 0.062 0.040 7 0.047 0.600 0.023 0.059 0.046 0.075 8 0.038 0.366 0.048 0.077 0.049 0.030
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表 3 已知比值样品的碳氮同位素测定结果
Table 3. Analytical results of samples with known carbon and nitrogen isotope ratio
同位素系列 δ13C测试值(‰) δ15N测试值(‰) 磺胺 小麦粉 磺胺 小麦粉 950℃ 900℃ 850℃ 800℃ 950℃ 900℃ 850℃ 800℃ 950℃ 900℃ 850℃ 800℃ 950℃ 900℃ 850℃ 800℃ 系列1 -26.42 -26.27 -26.46 -26.30 -26.94 -27.23 -27.75 -29.96 -1.57 -1.62 -2.52 0.50 2.81 2.39 3.52 1.91 系列2 -26.35 -26.28 -26.30 -26.45 -27.02 -27.26 -27.64 -27.03 -1.63 -1.58 -1.97 0.47 2.84 3.29 4.08 1.69 系列3 -26.42 -26.34 -26.44 -26.31 -27.02 -27.31 -27.20 -26.98 -1.14 -1.50 -2.59 1.09 2.68 3.45 6.12 2.03 系列4 -26.38 -26.21 -26.45 -26.24 -27.01 -27.28 -27.29 -27.07 -1.71 -1.31 -2.29 1.19 3.09 4.04 4.68 4.11 系列5 -26.37 -26.29 -26.33 -26.12 -27.04 -27.21 -27.58 -26.93 -1.11 -1.66 -2.77 0.35 2.45 3.83 5.41 7.03 系列6 -26.40 -26.26 -26.41 -26.25 -27.02 -27.05 -27.43 -29.91 -1.32 -1.70 -1.89 1.59 2.85 2.34 5.74 1.21 系列7 -26.32 -26.29 -26.40 -26.27 -26.98 -27.15 -27.54 -26.96 -1.54 -1.47 -2.08 -0.56 2.66 3.72 4.90 9.78 系列8 -26.45 -26.33 -26.39 -26.33 -27.03 -27.30 -27.11 -26.97 -1.26 -1.55 -2.95 0.78 3.02 3.03 3.96 7.69 平均值 -26.39 -26.30 -26.40 -26.28 -27.01 -27.22 -27.33 -27.73 -1.41 -1.55 -2.38 0.68 2.80 3.26 4.80 4.43 标准偏差 0.04 0.06 0.06 0.09 0.03 0.09 0.19 1.36 0.23 0.12 0.39 0.65 0.20 0.64 0.92 3.30 δ平均值-δ参考值 0.17 0.25 0.16 0.28 0.20 -0.01 -0.12 0.23 -0.18 -0.32 -1.15 1.91 -0.05 0.41 1.95 1.58
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表 4 不同含氮量样品各个反应温度相应的检测限
Table 4. The detection limit of different nitrogen content samples at each reaction temperature
样品 含氮量(%) 样品检测限(μg) 950℃ 900℃ 850℃ 2, 7-二甲基咔唑 7.2 32 45 90 咔唑 8.4 26 30 85 苏氨酸 11.8 16 21 52 磺胺 13.7 12 18 46 甘氨酸 18.7 9 15 42
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[1] 储雪蕾.一种新的、快速的碳、氮、硫同位素测定手段——EA-IRMS连线分析技术[J].矿物岩石地球化学通报, 1996, 15(4):259-262. http://www.oalib.com/paper/4573478
Chu X L.A new method of rapid measurements for C, N and S isotope ratios-on-line analytical method of EA-IRMS[J].Bulletin of Mineralogy Petrology and Geochemistry, 1996, 15(4):259-262. http://www.oalib.com/paper/4573478
[2] Glesemann A, Jager H J, Norman H R, et al.On-line sulfur-isotope determination using an elemental analyzer coupled to a mass spectrometer[J].Analytical Chemistry, 1994, 66:2816-2819. doi: 10.1021/ac00090a005
[3] Sun W W, Shen J, Zhang E L, et al.Stable nitrogen isotope record of lacustrine sediments in Lake Onuma (Northern Japan) indicates regional hydrological variability during the past four centuries[J].Quaternary International, 2016, 397:307-316.doi:org/10.1016/j.quaint.2015.07.036.
[4] Calleja M L, Batista F, Peacock M, et al.Changes in compound specific δ15N amino acid signatures and D/L ratios in marine dissolved organic matter induced by heterotrophic bacterial reworking[J].Marine Chemistry, 2013, 149:32-44.doi:org/10.1016/j.marchem.2012.12.001.
[5] Valery J T, Zewdu E, Albert G, et al.Reconstructing palaeoenvironment from δ13C and δ15N ransects values of soil organic matter:A calibration from arid and wetter elevation transects in Ethiopia[J]. Geoderma, 2008, 147:197-210. doi: 10.1016/j.geoderma.2008.09.001
[6] Reynard L M, Hedges R E. Stable hydrogen isotopes of bone collagen in palaeodietary and palaeoenvironmental reconstruction[J].Journal of Archaeological Science, 2008, 35:1934-1942. doi: 10.1016/j.jas.2007.12.004
[7] Wang G A, Li J Z, Liu X Z, et al.Variations in carbon isotope ratios of plants across a temperature gradient along the 400mm isoline of mean annual precipitation in North China and their relevance to paleovegetation reconstruction[J].Quaternary Science Reviews, 2013, 63:83-92. doi: 10.1016/j.quascirev.2012.12.004
[8] Handley L L, Raven J A.The use of natural abundance of nitrogen isotopes in plant physiology and ecology[J].Plant Cell and Environment, 1992, 15(9):965-985. doi: 10.1111/pce.1992.15.issue-9
[9] 刘贤赵, 张勇, 宿庆, 等.陆生植物氮同位素组成与气候环境变化研究进展[J].地球科学进展, 2014, 29(2):216-226. doi: 10.11867/j.issn.1001-8166.2014.02-0216
Liu X Z, Zhang Y, Su Q, et al.Progress of research on relationships between terrestrial plant nitrogen isotope composition and climate environment change[J].Advances in Earth Science, 2014, 29(2):216-226. doi: 10.11867/j.issn.1001-8166.2014.02-0216
[10] 梁越, 肖化云, 刘小真, 等.δ13C和δ15N指示不同生态类型湖泊无机氮及有机质来源[J].湖泊科学, 2014, 26(5):691-697. doi: 10.18307/2014.0506
Liang Y, Xiao H Y, Liu X Z, et al.Identifying provenance of inorganic and organic matter in different ecotype lakes using δ13C and δ15N[J].Journal of Lake Sciences, 2014, 26(5):691-697. doi: 10.18307/2014.0506
[11] 王周锋, 王政, 胡婧, 等.EA-MS测试过程中添加助燃剂的影响效应研究[J].质谱学报, 2008, 29(5):290-294. http://www.irgrid.ac.cn/handle/1471x/128566/handle/1471x/128554/browse?type=title&sort_by=1&order=ASC&year=&rpp=20&offset=237
Wang Z F, Wang Z, Hu J, et al.The effect of oxidizer appended during testing sample by EA-MS[J].Journal of Chinese Mass Spectrometry Society, 2008, 29(5):290-294. http://www.irgrid.ac.cn/handle/1471x/128566/handle/1471x/128554/browse?type=title&sort_by=1&order=ASC&year=&rpp=20&offset=237
[12] 王旭, 张福松, 丁仲礼.EA-Conflo-IRMS联机系统的燃烧转化率漂移及其对氮、碳同位素比值测定的影响[J].质谱学报, 2006, 27(2):104-109. http://kns.cnki.net/KCMS/detail/detail.aspx?filename=zpxb200602008&dbname=CJFD&dbcode=CJFQ
Wang X, Zhang F S, Ding Z L.Changes in the combustion transformation capability of EA-Conflo-IRMS and their impacts on nitrogen and carbon isotope ratio measurement[J].Journal of Chinese Mass Spectrometry Society, 2006, 27(2):104-109. http://kns.cnki.net/KCMS/detail/detail.aspx?filename=zpxb200602008&dbname=CJFD&dbcode=CJFQ
[13] 张媛媛, 贺行良, 孙书文, 等.元素分析仪-同位素比值质谱仪测定海洋沉积物有机碳稳定同位素方法初探[J].岩矿测试, 2012, 31(4):627-631. http://www.ykcs.ac.cn/article/id/ykcs_20120413
Zhang Y Y, He X L, Sun S W, et al.A preliminary study on the determination of organic carbon stable isotope of marine sediment by element analyzer-isotope ratio mass spectrometer[J].Rock and Mineral Analysis, 2012, 31(4):627-631. http://www.ykcs.ac.cn/article/id/ykcs_20120413
[14] 金贵善, 刘汉彬, 张建峰, 等.EA-IRMS测定有机及无机氮同位素条件探讨[J].地质学报, 2015, 89(增刊):85-86. http://kns.cnki.net/KCMS/detail/detail.aspx?filename=dzxe2015s1037&dbname=CJFD&dbcode=CJFQ
Jin G S, Liu H B, Zhang J F, et al.The conditions discussion of organic and inorganic nitrogen isotope by EA-IRMS[J].Acta Geologica Sinica, 2015, 89(Supplement):85-86. http://kns.cnki.net/KCMS/detail/detail.aspx?filename=dzxe2015s1037&dbname=CJFD&dbcode=CJFQ
[15] 王政, 刘卫国, 文启彬.土壤样品中氮同位素组成的元素分析仪-同位素质谱分析方法[J].质谱学报, 2005, 26(2):71-75. http://d.wanfangdata.com.cn/Periodical_zpxb200502002.aspx
Wang Z, Liu W G, Wen Q B.Measurement of nitrogen isotopic composition of soil samples by element analysis-isotope mass spectrometry[J].Journal of Chinese Mass Spectrometry Society, 2005, 26(2):71-75. http://d.wanfangdata.com.cn/Periodical_zpxb200502002.aspx
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