摘要
传统的氧同位素分析方法一般将各种形式的氧转化为CO2,再通过稳定同位素质谱测定其氧同位素组成,由于二氧化碳中的17O和13C在质谱中有相同的质荷比m/z,这种方法不能测得17O同位素的丰度,三氧同位素(16O、17O、18O)丰度分析的关键是17O同位素丰度的分析。为了测量17O同位素丰度,一般需要先将各种形式的氧转化为O2,然后利用稳定同位素质谱进行分析,转化过程复杂或者有危险。本文提出了一种新思路,应用稳定同位素质谱与碳同位素光谱相结合的方法分析17O/16O。先采用传统方法将各种形式的氧转化为CO2,再由多接收器稳定同位素质谱计测得CO2的质谱峰高比45/44(记为R45),同位素光谱如光腔衰荡光谱测得13C/12C(定义为R13),计算其同位素比值17O/16O=(R45-R13)/2,方法的分析精度好于±0.08‰(1σ)。该方法是在传统方法的基础上,增加一个CO2碳同位素光谱分析步骤,通过简单的数据处理就可以获得17O同位素组成,而无需将各种形式的氧转化为O2,18O同位素样品制备方法成熟,无危险性,且分析精度优于或相当于其他测试方法。
Since the discovery of mass-independent isotope effects, the study of triple oxygen isotope abundance has become a focus and frontier. In traditional oxygen isotopic ratio analysis methods, multiform oxygen is converted to CO2 and the oxygen isotopic ratios of CO2 are measured by Stable Isotope Mass Spectrometer. However, this method cannot be used to measure lVo isotopic abundance because ^17O and ^13C in carbon dioxide have the same m/z. The key for the triple oxygen isotope abundance analysis is to analyze the ^17O isotopic abundance. To measure the ^17O isotopic abundance muhiform oxygen to O2 is usually converted and then analyzed by Stable Isotope Mass Spectrometer, although the conversion process is complicated and/or dangerous. In this paper a new way to measure ^17Oo/^16O by Stable Isotope Mass Spectrometer and Isotopic Spectroscope is presented. The traditional method to convert multiform oxygen to CO2 is adopted. The CO2 was then analyzed by Stable Isotope Mass Spectrometer to obtain m/z 45/44 （defined as R45 ）, and by isotopic spectroscope such as cavity ring down spectroscope （CRDS） to obtain ^13 C/^12 C （ defined as R 13 ）. The ^17 O/^16O was calculated by ^17O/^16O = （ R45 - R13 ）/2. This method has an analytical precision which is better than ± 0.08%0 （1σ）. The new method is based on the traditional method with the addition of an analysis step of the carbon isotopic spectroscope for CO2. With simple data processing, the ^17O isotope composition was obtained without conversion of the multiform oxygen to O2. Moreover, there is no risk in sample preparation for ^18O isotopic analysis, and the precision is better than, or equal to, other methods.
出处
《岩矿测试》
CAS
CSCD
北大核心
2013年第3期392-397,共6页
Rock and Mineral Analysis
基金
中国地质大调查项目(1212011120276
12120113015100)
关键词
氧17
三氧同位素
光腔衰荡光谱
非质量分馏效应
oxygen 17
triple oxygen isotopes
cavity ring down spectroscope
mass-independent isotope fractionation
