气体稳定同位素比质谱法分析本底大气CO_2的δ^(13)C和δ^(18)O

Gas stable isotopic ratio mass spectrometry for measuring δ^(13)C and δ^(18)O in background atmospheric CO_2

将商用MAT253稳定同位素比质谱仪、Airtrap高效预浓缩气体捕集阱与自加工16口自动进样器集成,建立了高精度气体稳定同位素比质谱分析系统,用于程序化自动分析本底大气CO2的δ13C和δ18O.气样分析时用工作标气定量并穿插目标气测定,还定期用实验室上一级标气对工作标气和参比气进行标校,以保证分析结果的可靠和可比.结果表明,利用不同稳定同位素比范围的标气重复进样测试,发现该系统对δ13C和δ18O的分析精度分别优于0.03‰和0.06‰,能基本满足本底大气CO2的碳氧稳定同位素比分析需求和WMO/GAW质量目标.

A high precision gas stable isotopic ratio mass spectrometry system was set up to measure CO2 stable isotopes in background air samples. The system consisted of a MAT253 isotopic ratio mass spectrometry, an efficient airtrap extraction line and a custom designed auto sampler. In combination with periodic target injection, two working standards were injected before and after each of the unknown sample to control and monitor the system performance. The working standards were calibrated regularly to trace back higher level reference and to ensure measurement comparability. From repeated test, the system precision was better than 0.03‰ and 0.0‰ for δ^18 C and δ^18 O, respectively. The system could apply to the δ^18 C and δ^18O analysis in background atmospheric CO2 and essentially meet the WMO/GAW quality target.