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摘要
In this study, we performed a detailed comparison of stable and clumped isotopic data for an extraction method passing CO2 through a Porapak Q absorbent trap (PQT) driven by liquid nitrogen (LN method), an extraction method passing CO2 through a PQT driven by liquid nitrogen and high vacuum pumping (LN + HV method) and an extraction method without a PQT (NAT method), to examine the effectiveness and reliability of these methods. Changes in raw Delta(47) values along with collection times were used to constrain the optimum collection time (OCT) for each method. The OCT for the LN method shortened considerably when the PQT was warmer, i.e., from similar to 35 min to similar to 30 min when the PQT temperature changed from -15 degrees C to -12.5 degrees C. In contrast, the OCT for the LN + HV method displayed little change with the PQT temperature and was reduced to 25 min for both -15 degrees C and -25 degrees C. The contaminant removal efficiency of these methods was evaluated by Delta(48) values, revealing that the LN method (with a -12.5 degrees C to -25 degrees C PQT) and the LN + HV method (at -25 degrees C) could effectively remove contaminants compared with the NAT method. Therefore, the LN + HV method (at -25.0 degrees C) may serve as a promising sample preparation method for routine measurement because it can save time without compromising sample cleaning efficiency. Nevertheless, the LN + HV method yielded Delta(47) values 0.04-0.05% higher than the LN method at the same temperature, possibly because of different absorption-desorption states of the PQT in these methods. These findings provide useful clues for optimizing CO2 extraction methods for clumped isotope analysis.
- 出版日期2016-6-1
- 单位中国科学院地质与地球物理研究所兰州油气资源研究中心; 中国科学院地质与地球物理研究所
