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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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Real second-dimensional chromatogram (a) and GC×GC-TOFMS contour plot (b) of diamantanes identified in the condensate from Well DX 10 by GC×GC-TOFMS analysis under normal phase column system. The compounds are listed in Table 1.
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f3-ijms-13-11399: Real second-dimensional chromatogram (a) and GC×GC-TOFMS contour plot (b) of diamantanes identified in the condensate from Well DX 10 by GC×GC-TOFMS analysis under normal phase column system. The compounds are listed in Table 1.

Mentions: Nine diamantane homologues were identified, ranging from C15 to C17 (No. 18 to 26 peaks in Figure 3a and Table 1), of which the No. 22 compound is the overlapped peak of 1,2-dimethyl-diamantane and 2,4-dimethyl diamantane. The No. 22, 23 and 24 peaks commonly coelute in conventional GC-MS analysis [18]. In contrast, in GC×GC-TOFMS analysis, the No. 23 and 24 peaks have the same first-dimensional retention time of 4934 s (Table 1). However, their second-dimension retention times are 2.164 s and 2.330 s, respectively, showing a difference of 0.166 s (Table 1). Thus, they can be preliminarily separated based on masses by first-dimensional analysis, and can be effectively separated by second-dimensional analysis (Table 1, Figure 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 diamantanes identified in the condensate from Well DX 10 by GC×GC-TOFMS analysis under normal 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

f3-ijms-13-11399: Real second-dimensional chromatogram (a) and GC×GC-TOFMS contour plot (b) of diamantanes identified in the condensate from Well DX 10 by GC×GC-TOFMS analysis under normal phase column system. The compounds are listed in Table 1.
Mentions: Nine diamantane homologues were identified, ranging from C15 to C17 (No. 18 to 26 peaks in Figure 3a and Table 1), of which the No. 22 compound is the overlapped peak of 1,2-dimethyl-diamantane and 2,4-dimethyl diamantane. The No. 22, 23 and 24 peaks commonly coelute in conventional GC-MS analysis [18]. In contrast, in GC×GC-TOFMS analysis, the No. 23 and 24 peaks have the same first-dimensional retention time of 4934 s (Table 1). However, their second-dimension retention times are 2.164 s and 2.330 s, respectively, showing a difference of 0.166 s (Table 1). Thus, they can be preliminarily separated based on masses by first-dimensional analysis, and can be effectively separated by second-dimensional analysis (Table 1, Figure 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