元素分析仪-同位素比值质谱仪测定海洋沉积物有机碳稳定同位素方法初探

初步建立了利用元素分析仪-同位素比值质谱仪(EA-IRMS)联用技术测定海洋沉积物中有机碳稳定同位素的方法。标定了标准工作参考气CO2(δ13CvsPDB为-32.053‰);验证了仪器的稳定性,标准偏差为0.009‰;当离子流强度范围为0.4～8.7 V时,总体线性为0.0337‰/V,小于仪器线性指标0.06‰/V的要求;同时测定了国家标准物质GBW 04408、国际标准物质Urea和海洋沉积物样品M01的精密度和准确度,标准偏差在0.04‰～0.13‰范围内;并在三家实验室进行了测量比对实验,标准偏差小于0.20‰,满足地质样品再现性0.5‰的要求。所选样品区域δ13Corg范围为-25.29‰～-22.30‰,表明该海域总有机碳是陆源和海源两种来源的混合物。

A Preliminary Study on the Determination of Organic Carbon Stable Isotope of Marine Sediment by Element Analyzer-Isotope Ratio Mass Spectrometer

Element Analyzer-Isotope Ratio Mass Spectrometer(EA-IRMS) technology was applied to determine organic carbon stable isotopes of marine sediment.Pure CO2 reference gas was calibrated via GBW 04408,and the δ13CvsPDB value of pure CO2 was determined to be-32.053‰.The stability and linearity of the EA-IRMS system were tested and verified through several experimental comparisons.The standard deviation of stability was 0.009‰.When ion intensities ranged from 0.4 to 8.7 V,the linearity of EA-IRMS system was 0.0337‰/V which was less than the requirement of linearity proxy of 0.06‰/V.Moreover,the precision and accuracy of the results for the national standard material of GBW 04408,international standard material of Urea and marine sediment sample of M01 were measured.The standard deviation was 0.13‰.The marine sediment samples were measured at three different labs.The standard deviation of the comparison results was less than 0.20‰ and met the need of reproducibility of 0.5‰.The TOC contents from marine sediment samples ranged from 0.13‰ to 1.11‰,with δ13Corg values ranging from-25.29‰ to-22.30‰,which indicate the derivation of organic matter from mixed terrestrial and marine organic materials.