Study on Specific Carbon Isotope Fractionation of n-Alkanes during Column Chromatography Separation-Molecular Sieve Complexation Adsorption
BACKGROUND Before analyzing the carbon isotopes of n-alkanes by gas chromatography-gas isotope mass spectrometry (GC-IRMS), it is necessary to pre-separate and enrich n-alkanes and isoparaffins in saturated hydrocarbon samples. Whether the carbon isotope fractionation of n-alkanes occurs is the key...
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Science Press, PR China
2021-05-01
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| Series: | Yankuang ceshi |
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| Online Access: | http://www.ykcs.ac.cn/en/article/doi/10.15898/j.cnki.11-2131/td.202005030063 |
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| author | DONG Hao-wei ZHAO Jia-yu ZENG Fan-gang XIE Man-man SHANG Wen-yu WANG Shu-xian SUN Qing |
| author_facet | DONG Hao-wei ZHAO Jia-yu ZENG Fan-gang XIE Man-man SHANG Wen-yu WANG Shu-xian SUN Qing |
| author_sort | DONG Hao-wei |
| collection | DOAJ |
| description | BACKGROUND Before analyzing the carbon isotopes of n-alkanes by gas chromatography-gas isotope mass spectrometry (GC-IRMS), it is necessary to pre-separate and enrich n-alkanes and isoparaffins in saturated hydrocarbon samples. Whether the carbon isotope fractionation of n-alkanes occurs is the key for the high-precision analysis of the carbon isotope ratio. OBJECTIVES To determine isotopic fractionation characteristics for n-alkanes during column chromatography and molecular sieve separation. METHODS Saturated hydrocarbon components were extracted with a 500mg/3mL SPE silica gel column using 2mL n-pentane. After separating by a 5Å molecular sieve and extracting by a mixture solvent of cyclohexane and n-pentane, n-alkanes were concentrated and analyzed by gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). RESULTS During column chromatographic separation, the carbon isotope ratio of most n-alkanes differed from -0.2‰ to 0.2‰. When n-alkanes was not completely complexed by 5Å molecular sieve, the uncomplexed alkane carbon isotope was about 0.7‰ heavier, and weak carbon isotope fractionation occured, but it did not affect the eluted n-alkanes carbon isotope ratio. Eluted with cyclohexane-n-pentane mixed solvent, the carbon isotope values before and after the elution differed from-0.2‰ to 0.5‰, and eluted in the same way for the second time, the difference between the eluted n-alkanes carbon isotope and simulate sample was between -0.3‰ and 0.2‰. Analyzing the carbon isotope ratios of n-alkanes with different recoveries (>20%), the difference between carbon isotopes of n-alkanes before and after pretreatment was within 0.3‰. It was found that when the recovery was as low as 20%, the carbon isotope ratios did not undergo significant fractionation. CONCLUSIONS The column chromatography-5Å molecular sieve adsorption and mixed solvent elution method is suitable for the analysis of carbon isotope ratios of normal alkanes, which yields a recovery greater than 20%. |
| first_indexed | 2024-04-10T23:08:46Z |
| format | Article |
| id | doaj.art-45551b28edf646a5a279bb4294fee50d |
| institution | Directory Open Access Journal |
| issn | 0254-5357 |
| language | English |
| last_indexed | 2024-04-10T23:08:46Z |
| publishDate | 2021-05-01 |
| publisher | Science Press, PR China |
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| series | Yankuang ceshi |
| spelling | doaj.art-45551b28edf646a5a279bb4294fee50d2023-01-13T07:06:42ZengScience Press, PR ChinaYankuang ceshi0254-53572021-05-0140334935710.15898/j.cnki.11-2131/td.202005030063yk202005030063Study on Specific Carbon Isotope Fractionation of n-Alkanes during Column Chromatography Separation-Molecular Sieve Complexation AdsorptionDONG Hao-wei0ZHAO Jia-yu1ZENG Fan-gang2XIE Man-man3SHANG Wen-yu4WANG Shu-xian5SUN Qing6National Research Center for Geoanalysis, Beijing 100037, ChinaKey Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, ChinaSchool of Environment & Natural Resources, Renmin University of China, Beijing 100872, ChinaNational Research Center for Geoanalysis, Beijing 100037, ChinaNational Research Center for Geoanalysis, Beijing 100037, ChinaNational Research Center for Geoanalysis, Beijing 100037, ChinaNational Research Center for Geoanalysis, Beijing 100037, ChinaBACKGROUND Before analyzing the carbon isotopes of n-alkanes by gas chromatography-gas isotope mass spectrometry (GC-IRMS), it is necessary to pre-separate and enrich n-alkanes and isoparaffins in saturated hydrocarbon samples. Whether the carbon isotope fractionation of n-alkanes occurs is the key for the high-precision analysis of the carbon isotope ratio. OBJECTIVES To determine isotopic fractionation characteristics for n-alkanes during column chromatography and molecular sieve separation. METHODS Saturated hydrocarbon components were extracted with a 500mg/3mL SPE silica gel column using 2mL n-pentane. After separating by a 5Å molecular sieve and extracting by a mixture solvent of cyclohexane and n-pentane, n-alkanes were concentrated and analyzed by gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). RESULTS During column chromatographic separation, the carbon isotope ratio of most n-alkanes differed from -0.2‰ to 0.2‰. When n-alkanes was not completely complexed by 5Å molecular sieve, the uncomplexed alkane carbon isotope was about 0.7‰ heavier, and weak carbon isotope fractionation occured, but it did not affect the eluted n-alkanes carbon isotope ratio. Eluted with cyclohexane-n-pentane mixed solvent, the carbon isotope values before and after the elution differed from-0.2‰ to 0.5‰, and eluted in the same way for the second time, the difference between the eluted n-alkanes carbon isotope and simulate sample was between -0.3‰ and 0.2‰. Analyzing the carbon isotope ratios of n-alkanes with different recoveries (>20%), the difference between carbon isotopes of n-alkanes before and after pretreatment was within 0.3‰. It was found that when the recovery was as low as 20%, the carbon isotope ratios did not undergo significant fractionation. CONCLUSIONS The column chromatography-5Å molecular sieve adsorption and mixed solvent elution method is suitable for the analysis of carbon isotope ratios of normal alkanes, which yields a recovery greater than 20%.http://www.ykcs.ac.cn/en/article/doi/10.15898/j.cnki.11-2131/td.202005030063specific carbon isotopes of n-alkanescarbonisotope fractionscolumn chromatography5å molecular sievemixed solvent elutiongas chromatography-combustion-isotope ratio mass spectrometry (gc-c-irms) |
| spellingShingle | DONG Hao-wei ZHAO Jia-yu ZENG Fan-gang XIE Man-man SHANG Wen-yu WANG Shu-xian SUN Qing Study on Specific Carbon Isotope Fractionation of n-Alkanes during Column Chromatography Separation-Molecular Sieve Complexation Adsorption Yankuang ceshi specific carbon isotopes of n-alkanes carbonisotope fractions column chromatography 5å molecular sieve mixed solvent elution gas chromatography-combustion-isotope ratio mass spectrometry (gc-c-irms) |
| title | Study on Specific Carbon Isotope Fractionation of n-Alkanes during Column Chromatography Separation-Molecular Sieve Complexation Adsorption |
| title_full | Study on Specific Carbon Isotope Fractionation of n-Alkanes during Column Chromatography Separation-Molecular Sieve Complexation Adsorption |
| title_fullStr | Study on Specific Carbon Isotope Fractionation of n-Alkanes during Column Chromatography Separation-Molecular Sieve Complexation Adsorption |
| title_full_unstemmed | Study on Specific Carbon Isotope Fractionation of n-Alkanes during Column Chromatography Separation-Molecular Sieve Complexation Adsorption |
| title_short | Study on Specific Carbon Isotope Fractionation of n-Alkanes during Column Chromatography Separation-Molecular Sieve Complexation Adsorption |
| title_sort | study on specific carbon isotope fractionation of n alkanes during column chromatography separation molecular sieve complexation adsorption |
| topic | specific carbon isotopes of n-alkanes carbonisotope fractions column chromatography 5å molecular sieve mixed solvent elution gas chromatography-combustion-isotope ratio mass spectrometry (gc-c-irms) |
| url | http://www.ykcs.ac.cn/en/article/doi/10.15898/j.cnki.11-2131/td.202005030063 |
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