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Diamondoid characterization in condensate by comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry: The Junggar Basin of Northwest China.

Li S, Hu S, Cao J, Wu M, Zhang D - Int J Mol Sci (2012)

Bottom Line: However, they are very difficult to separate and accurately quantify by conventional geochemical methods due to their low abundance in oil.It not only separates the compounds that coelute in conventional GC-MS (e.g., 4, 8-dimethyl-diamantane and trimethyl-diamantane) but also allows the identification of compounds that were not previously detected (e.g., trimethyl-diamantane (15A)).The diamondoid indexes indicate that a representative condensate from Well DX 10 is highly mature with equivalent Ro being approximately 1.5%.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Tectonics and Petroleum Resources (China University of Geosciences), Ministry of Education, Wuhan 430074, China; E-Mails: hushzh@cug.edu.cn (S.H.); zdm2007@cug.edu.cn (D.Z.).

ABSTRACT
Diamondoids in crude oil are useful for assessing the maturity of oil in high maturation. However, they are very difficult to separate and accurately quantify by conventional geochemical methods due to their low abundance in oil. In this paper, we use comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GC×GC-TOFMS) to study the compounds in condensates from the Junggar Basin of northwest China and address their geological and geochemical applications. GC×GC-TOFMS improves the resolution and separation efficiency of the compounds. It not only separates the compounds that coelute in conventional GC-MS (e.g., 4, 8-dimethyl-diamantane and trimethyl-diamantane) but also allows the identification of compounds that were not previously detected (e.g., trimethyl-diamantane (15A)). A reversed-phase column system improves the separation capabilities over the normal phase column system. The diamondoid indexes indicate that a representative condensate from Well DX 10 is highly mature with equivalent Ro being approximately 1.5%.

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Related in: MedlinePlus

Real second-dimensional chromatogram (a) and GC×GC-TOFMS contour plot (b) of adamantanes identified in the condensate from Well DX 10 by GC×GC-TOFMS analysis under reversed phase column system. The compounds are listed in Table 1.
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f4-ijms-13-11399: Real second-dimensional chromatogram (a) and GC×GC-TOFMS contour plot (b) of adamantanes identified in the condensate from Well DX 10 by GC×GC-TOFMS analysis under reversed phase column system. The compounds are listed in Table 1.

Mentions: Analytical results conducted in normal and reversed phase column systems show differences (Table 1). In the normal system, the first-dimensional and second-dimensional retention times of the compounds with the same characteristic fragment ions increase simultaneously, showing a right-declined imbricate distribution (Figures 1 and 3). By contrast, in the reversed system, the second-dimensional retention time of the compounds decreases while the first-dimensional retention time increases, demonstrating a left-declined imbricate distribution (Figures 4 and 5). In the same second-dimensional chromatogram, the dispersion degree of compounds under the reversed system is obviously larger than that in the normal system, such as the No. 1 and 5 peaks in Table 1, whose distribution span is the largest. Although the second-dimensional retention time interval is only 0.47 s in the normal system, it is far greater in the reversed system (up to 1.28 s; Table 1, Figure 4). With respect to the second-dimensional retention time of the two pairs of cis trans isomers (No. 7 and No. 8, and No. 11 and No. 12), the difference in the reversed system is greater than that in the normal system (Table 1). As to the diamantanes, the first-dimensional retention time interval between No. 18 and 24 peaks is 210 s in the normal system, while it is 245 s in the reversed system (Table 1). In contrast, the second-dimensional retention time interval is 0.375 s and 0.480 s for the normal and reversed systems, respectively. Therefore, in summary, the identification of diamondoids is better in the reversed system (Figures 4 and 5) than in the normal system (Figures 1 and 3).


Diamondoid characterization in condensate by comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry: The Junggar Basin of Northwest China.

Li S, Hu S, Cao J, Wu M, Zhang D - Int J Mol Sci (2012)

Real second-dimensional chromatogram (a) and GC×GC-TOFMS contour plot (b) of adamantanes identified in the condensate from Well DX 10 by GC×GC-TOFMS analysis under reversed phase column system. The compounds are listed in Table 1.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC3472753&req=5

f4-ijms-13-11399: Real second-dimensional chromatogram (a) and GC×GC-TOFMS contour plot (b) of adamantanes identified in the condensate from Well DX 10 by GC×GC-TOFMS analysis under reversed phase column system. The compounds are listed in Table 1.
Mentions: Analytical results conducted in normal and reversed phase column systems show differences (Table 1). In the normal system, the first-dimensional and second-dimensional retention times of the compounds with the same characteristic fragment ions increase simultaneously, showing a right-declined imbricate distribution (Figures 1 and 3). By contrast, in the reversed system, the second-dimensional retention time of the compounds decreases while the first-dimensional retention time increases, demonstrating a left-declined imbricate distribution (Figures 4 and 5). In the same second-dimensional chromatogram, the dispersion degree of compounds under the reversed system is obviously larger than that in the normal system, such as the No. 1 and 5 peaks in Table 1, whose distribution span is the largest. Although the second-dimensional retention time interval is only 0.47 s in the normal system, it is far greater in the reversed system (up to 1.28 s; Table 1, Figure 4). With respect to the second-dimensional retention time of the two pairs of cis trans isomers (No. 7 and No. 8, and No. 11 and No. 12), the difference in the reversed system is greater than that in the normal system (Table 1). As to the diamantanes, the first-dimensional retention time interval between No. 18 and 24 peaks is 210 s in the normal system, while it is 245 s in the reversed system (Table 1). In contrast, the second-dimensional retention time interval is 0.375 s and 0.480 s for the normal and reversed systems, respectively. Therefore, in summary, the identification of diamondoids is better in the reversed system (Figures 4 and 5) than in the normal system (Figures 1 and 3).

Bottom Line: However, they are very difficult to separate and accurately quantify by conventional geochemical methods due to their low abundance in oil.It not only separates the compounds that coelute in conventional GC-MS (e.g., 4, 8-dimethyl-diamantane and trimethyl-diamantane) but also allows the identification of compounds that were not previously detected (e.g., trimethyl-diamantane (15A)).The diamondoid indexes indicate that a representative condensate from Well DX 10 is highly mature with equivalent Ro being approximately 1.5%.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Tectonics and Petroleum Resources (China University of Geosciences), Ministry of Education, Wuhan 430074, China; E-Mails: hushzh@cug.edu.cn (S.H.); zdm2007@cug.edu.cn (D.Z.).

ABSTRACT
Diamondoids in crude oil are useful for assessing the maturity of oil in high maturation. However, they are very difficult to separate and accurately quantify by conventional geochemical methods due to their low abundance in oil. In this paper, we use comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GC×GC-TOFMS) to study the compounds in condensates from the Junggar Basin of northwest China and address their geological and geochemical applications. GC×GC-TOFMS improves the resolution and separation efficiency of the compounds. It not only separates the compounds that coelute in conventional GC-MS (e.g., 4, 8-dimethyl-diamantane and trimethyl-diamantane) but also allows the identification of compounds that were not previously detected (e.g., trimethyl-diamantane (15A)). A reversed-phase column system improves the separation capabilities over the normal phase column system. The diamondoid indexes indicate that a representative condensate from Well DX 10 is highly mature with equivalent Ro being approximately 1.5%.

Show MeSH
Related in: MedlinePlus