A Carbon-13 Isotope Analyzer Based on CO Emission Spectroscopy

同位素碳分析为研究代谢途径和追踪环境中的碳转化提供了有价值的工具。PI建议开发一种光学技术来方便地测量碳同位素（13C/12C）比率。该仪器将使用线性光电二极管阵列对含碳分子等离子体发射产生的光谱进行成像。算法将被应用于去除光谱干扰和校正由于样品压力和功率耦合变化而引起的同位素比例偏移。最初的工作表明，一个排放系统可以用来确定二氧化碳样品中的13C/12C比率，相对精度可达2.5%，可提高6倍。对数据处理的数学方法也进行了评价。在第二阶段提出的后续研究将涉及采用排放方法来确定气相色谱仪中CO2洗脱液的13C/12C比率。系统的改进，包括设计和测试一个适合在大气压下采样的入口系统，可能会导致一个自动化的样品处理系统，该系统将与碳氮分析仪相结合，用于在线测定13C和15N的同位素比率。成功完成第二阶段的目标将导致开发出一种廉价、可靠的替代质谱法的方法，用于测定来自同一样品的13C、15N和18O的同位素比率。该仪器可方便地用于示踪剂研究，经过进一步改进，可用于医学和环境领域的自然丰度分析，从而使更广泛的研究人员更容易获得同位素测量。

Isotopic carbon analysis provides a valuable tool for studies of metabolic pathways and for tracing carbon transformations in the environment. The PI proposes to develop an optical technique for the convenient measurement of carbon isotopic (13C/12C) ratios. The instrument will use a linear photodiode array to image the spectra arising from plasm-emission of carbon-containing molecules. Algorithms will be applied to remove spectral interferences and to correct for isotopic ration shifts due to variations in sample pressure and power coupling. Initial work demonstrated that an emission system could be used to determine the 13C/12C ratio in CO2 samples up to a relative precision of 2.5% which could be improved by a factor of 6. Mathematical methods were also evaluated for data processing. Follow-on studies proposed in phase II will involve adapting the emission method for determining 13C/12C ratios for CO2 eluant from a gas chromatograph. System refinements, including the design and testing of an inlet system suitable for sampling at atmospheric pressure, may lead to an automated sample processing system which will be coupled to a carbon-nitrogen analyzer for on-line isotope ratio determinations of both 13C and 15N. Successful accomplishment of the objectives of phase II should result in the development of an inexpensive, reliable alternative to mass spectrometry for the determination of the isotopic ratios of 13C and eventually 15N, and 18O from the same sample. The instrument could be readily used for tracer studies, and with further refinements may be useful for natural abundance analyses, in both medical and environmental fields thereby making isotopic measurements more accessible to a broader range of researchers.