School of Geography and Earth Sciences, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4K1, Canada.
Rapid Commun Mass Spectrom. 2014 Mar 15;28(5):553-62. doi: 10.1002/rcm.6812.
The oxygen isotope study of water reservoirs (δ(18)OH2O values) and the carbon isotope study of dissolved inorganic carbon (δ(13)CDIC values) are powerful tools to decipher Earth's past and present environmental changes. This study presents a novel online analytical technique, namely the DIC evolved CO2 Gas Equilibration Method (DIC-CO2-GEM), in which the δ(18)OH2O and δ(13)CDIC values can be simultaneously determined from a single solution sample.
The DIC-CO2-GEM measures both δ(18)OH2O and δ(13)CDIC values concurrently by combining the fundamental principles of the classic CO2-H2O equilibration and gas evolution methods, respectively. Phosphoric acid is used to convert dissolved inorganic carbon in a solution sample of 0.2 mL into gaseous CO2, which is then equilibrated with the solution at 25 °C. The oxygen and carbon isotope compositions are subsequently determined via continuous-flow isotope ratio mass spectrometry from the single solution sample.
Results obtained employing the DIC-CO2-GEM are in good agreement (<± 0.07‰ for δ(18)OH2O values and < < ± 0.1‰ for δ(13)CDIC values) with those acquired using each of the traditional techniques. For both oxygen and carbon isotope measurements, an addition of 0.01 mL phosphoric acid yields the most consistent results between our technique and the traditional methods.
Devised to combine the traditional approaches independently assessing δ(18)OH2O and δ(13)CDIC values, the DIC-CO2-GEM is less complex and highly efficient. It preserves the modern precision requirements for oxygen (± 0.09‰) and carbon (± 0.18‰) isotope analyses while accurately measuring both parameters simultaneously. This innovative method generates an abundance of data while minimizing resources and is suitable for a variety of practical applications.
储水层的氧同位素研究（δ(18)OH2O 值）和溶解无机碳的碳同位素研究（δ(13)CDIC 值）是揭示地球过去和现在环境变化的有力工具。本研究提出了一种新颖的在线分析技术，即 DIC 衍生 CO2 气体平衡法（DIC-CO2-GEM），该技术可从单个溶液样品中同时测定 δ(18)OH2O 和 δ(13)CDIC 值。
DIC-CO2-GEM 通过分别结合经典 CO2-H2O 平衡和气体逸出方法的基本原理，同时测量 δ(18)OH2O 和 δ(13)CDIC 值。在 0.2ml 的溶液样品中使用磷酸将溶解的无机碳转化为气态 CO2，然后在 25°C 下与溶液平衡。随后通过连续流动同位素比质谱仪从单个溶液样品中测定氧和碳同位素组成。
使用 DIC-CO2-GEM 获得的结果与传统技术的结果非常吻合（δ(18)OH2O 值的差异<±0.07‰，δ(13)CDIC 值的差异< <±0.1‰）。对于氧和碳同位素测量，在我们的技术和传统方法之间，添加 0.01ml 磷酸可获得最一致的结果。
DIC-CO2-GEM 旨在结合独立评估 δ(18)OH2O 和 δ(13)CDIC 值的传统方法，其复杂性较低且效率高。它保留了现代对氧（±0.09‰）和碳（±0.18‰）同位素分析的精度要求，同时准确地同时测量这两个参数。这种创新的方法在最大限度地减少资源的同时生成大量数据，适用于各种实际应用。
