MRI: Development of Carbon 14 Analyzer

碳14(14C)存在于生物圈中，相对于碳12，其丰度约为万亿分之一，并以5730年的半衰期衰变，从而为碳的年代测定提供了一个标签。此外，在生理学研究中，标记有14C的化合物通常用于跟踪新陈代谢。在大气科学中，14C含量的微小变化可以监测化石燃料燃烧释放到大气中的二氧化碳数量。现在对14C的灵敏测量需要使用大型、专用和昂贵的粒子加速器。在本项目中，将开发一种新的基于激光的超灵敏14C检测仪，用于14C的常规定量。由此产生的系统将易于操作，并允许使用极小的(约0.1毫克)样品。第一批仪器的用户将来自三个广泛的领域：环境监测、生理学研究和小样本分析，所有这些都需要系统的独特能力。该项目使用了一种新的基于超灵敏激光的分析技术--腔内光电谱(ICOGS)，它能够检测14C标记的二氧化碳。计划实现三个主要发展目标：优化激光系统；编写样品处理和引入协议；以及制定校准和标准方法和设备。将建造两台具有共同技术的仪器--一台用于小样本和环境监测的高灵敏度设备，另一台用于14C示踪剂标记的有机和生物样品的常规分析的低灵敏度设备。该项目的成功完成将提供实验室规模的、用户友好的仪器，用于生物和环境样品中14C的高度灵敏测量。它还将极大地扩大可能的测量范围，并增加用户社区的规模。由于该仪器可以容纳二氧化碳的连续流动，因此实时大气监测也是可能的。仪器开发计划的一个主要成果将是向来自行业、政府和学术界的广泛用户社区以及潜在的商业供应商转让技术。所取得的成果将提交给跨学科科学期刊以及区域和国家会议。

Carbon 14 (14C) exists in the biosphere with an abundance of about 1 part per trillion relative to carbon 12, and decays with a half-life of 5730 years thus providing a tag for carbon dating. In addition, compounds labeled with 14C are routinely used to trace metabolism in physiology research. In atmospheric science, small changes in 14C content can monitor how much carbon dioxide is being released into the atmosphere from fossil fuel burning. Sensitive measurement of 14C now requires the use of large dedicated and expensive particle accelerators. In this project, a new laser based ultra-sensitive 14C detection instrument for routine quantitation of 14C will be developed. The resulting system will be easy to operate and allow the use of extremely small (of order 0.1 mg) samples. Users of the first instruments will come from three broad areas: environmental monitoring, physiology studies, and small sample analysis, all of which require the unique capabilities of the system. The project uses a new ultra-sensitive laser based analytical technique, intracavity optogalvanic spectroscopy (ICOGS), which enables the detection of 14C labeled carbon dioxide. Three major development goals are planned: optimization of the laser system; preparation of sample handling and introduction protocols; and development of calibration and standards methodology and equipment. Two instruments with a common technology will be built- a high sensitivity device for small sample and environmental monitoring and a lower sensitivity device for routine analysis of organic and biological samples labeled with 14C tracers. Successful completion of the project will make available laboratory size, user-friendly instruments for highly sensitive measurements of 14C in biological and environmental samples. It will also greatly expand the range of measurements possible and increase the size of the user community. Because the instrument can accommodate continuous flow of carbon dioxide, real-time atmospheric monitoring is also possible. A major outcome of the instrument development program will be technology transfer to both a broad user community from industry, government and academia; as well as to potential commercial suppliers. Results obtained will be submitted to interdisciplinary scientific journals and at regional and national meetings.