Determination of Isotope Composition of Dissolved Inorganic Carbon by Gas Chromatography-Conventional Isotope-ratio Mass Spectrometry

The studies of dissolved inorganic carbon (DIC) have important scientific significance and wide applications. In this study, a series of DIC samples with different concentrations were prepared by using NaHCO3. In this experiment, a novel method was established to analyze DIC carbon isotope compositions. The results achieved by the method were stable and reliable, and the different concentration samples showed only 0.2‰–0.5‰ of deviation between the DIC sample and the NaHCO3. By referring to the results of the control group, this method proved to be effective to prevent the interference from atmospheric CO2 and other organic materials, which ensured the accuracy of the test results. Besides these, the method has the advantage to meet the requirements of DIC research in the absence of specialized equipments, and it can be done under the conventional conditions in the lab. The method also does not require the pretreatment equipments and can be easily done offline. Therefore, the operation is simple, fast, and low cost, and it is applicable to the various DIC samples in nature, particularly for a lot of DIC samples.