Two new organic reference materials for δ13C and δ15N measurements and a new value for the δ13C of NBS 22 oil
Two new organic reference materials for δ13C and δ15N measurements and a new value for the δ13C of NBS 22 oil
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DOI：
10.1002/rcm.1219
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发表时间：
2003-01-01
影响因子：
2
通讯作者：
Böhlke, JK
中科院分区：
文献类型：
--
作者：
Qi, HP;Coplen, TB;Böhlke, JK
分析级L-谷氨酸化学稳定，C/N摩尔比为5，接近许多天然生物材料，如血液和动物组织。制备了两种C-13和N-15丰度明显不同的L-谷氨酸标准物质，用作C和N同位素测量的有机标准物质。USGS 40是分析级L-谷氨酸，相对于VPDB，其δ（13）C值为-26.24 ‰，相对于空气中的N-2，其δ（15）N值为-4.52 ‰。USGS 41通过用富含C-13和N-15的L-谷氨酸溶解分析级L-谷氨酸来制备。USGS 41的δ（13）C值为+37.76ppm，δ（15）N值为+47.57ppm。两种材料的δ（13）C和δ（15）N值都是相对于国际参考材料NBS 19碳酸钙测量的（δ（13）C =+1.95ppm），L-SVEC碳酸锂（δ（13）C =-46.48ppm），IAEA-N-1硫酸铵（δ（15）N = 0.43ppm）和USGS 32硝酸钾（δ（15）N = 180 ppm）。USGS 40和USGS 41都是同位素均匀的;在100 μ g的量中，δ（13）C的再现性优于0.13ppm，δ（15）N的再现性优于0.13ppm。这两种同位素参考物质可用于（i）校准当地实验室参考物质，以及（ii）在各种生物材料的同位素分析中量化随时间的漂移、质量相关分馏和同位素比标度收缩。本文给出的同位素结果得出NBS 22油的δ（13）C值为-29.91ppm，而通常接受的值为-29.78ppm，离线空白校正可能无法令人满意地量化。出版社：John Wiley Sons，Ltd.
Analytical grade L-glutamic acid is chemically stable and has a C/N mole ratio of 5, which is close to that of many of natural biological materials, such as blood and animal tissue. Two L-glutamic acid reference materials with substantially different C-13 and N-15 abundances have been prepared for use as organic reference materials for C and N isotopic measurements. USGS40 is analytical grade L-glutamic acid and has a delta(13)C value of -26.24parts per thousand relative to VPDB and a delta(15)N value of -4.52parts per thousand relative to N-2 in air. USGS41 was prepared by dissolving analytical grade L-glutamic acid with L-glutamic acid enriched in C-13 and N-15. USGS41 has a delta(13)C value of +37.76parts per thousand and a delta(15)N value of +47.57parts per thousand. The delta(13)C and delta(15)N values of both materials were measured against the international reference materials NBS 19 calcium carbonate (delta(13)C = +1.95parts per thousand), L-SVEC lithium carbonate (delta(13)C = -46.48parts per thousand), IAEA-N-1 ammonium sulfate (delta(15)N = 0.43parts per thousand), and USGS32 potassium nitrate (delta(15)N = 180parts per thousand) by on-line combustion continuous-flow and off-line dual-inlet isotope-ratio mass spectrometry. Both USGS40 and USGS41 are isotopically homogeneous; reproducibility of delta(13)C is better than 0.13parts per thousand, and that of delta(15)N is better than 0.13parts per thousand in 100-mug amounts. These two isotopic reference materials can be used for (i) calibrating local laboratory reference materials, and (ii) quantifying drift with time, mass-dependent fractionations, and isotope-ratio-scale contraction in the isotopic analysis of various biological materials. Isotopic results presented in this paper yield a delta(13)C value for NBS 22 oil of -29.91parts per thousand, in contrast to the commonly accepted value of -29.78parts per thousand for which off-line blank corrections probably have not been quantified satisfactorily. Published in 2003 by John Wiley Sons, Ltd.