Terpanes tricyclic

Tricyclic terpanes (Structure IV, Fig. 1), usually ranging from C19H34 to C30H56, and in some cases to C45H86 [68,124-126]... 

Novel biomarkers, i.e. tracer derivatives from unknown natural products, are sometimes encountered in geological or environmental samples, typically as hydrocarbons. The detection and determination of these compounds are usually based on the interpretation of mass spectra in GC-MS analyses. The proofs of chemical structures are based on the proposed interpretation of the MS data, separation and purification of the unknown compounds, exact structure determination by NMR methods or X-ray crystallography (if the compound is a solid that can be crystallized), and finally, comparison with a synthetic standard. The next question concerns the biological source of the biomarker precursor compound. Many biomarkers still have no proven natural product precursors nor known biological sources (e.g. perylene, tricyclic terpanes). " ... 

Aquino Neto FR, Restle A, Connan J, Albrecht P, Ourisson G, Novel tricyclic terpanes (Cig, C20) in sediments and petroleums. Tetrahedron Letters 23 2027-2030, 1982. 

Simoneit BRT, Leif RN, Radler de Aquino Neto F, Almeida Azevedo D, Pinto AC, Albrecht P, On the presence of tricyclic terpane hydrocarbons in Permian tasmanite algae, Naturwissenschaften 77 380-383, 1990. 

The most common compounds in this class are cheilanthanes (54) (= 13-methyl, 14-alkylpodo-carpanes), tricyclic terpanes that extend from C19... 

Farrimond P., Bevan J. C., and Bishop A. N. (1999) Tricyclic terpane maturity parameters response to heating by an igneous intrusion. Org. Geochem. 30, 1011-1019. 

Moldowan J. M. and Seifert W. K. (1983) Identification of an extended series of tricyclic terpanes in petroleum. Geochim. Cosmochim. Acta 47, 1531-1534. 

Wang T.-G. (1991) A novel tricyclic terpane biomarker series in the upper Proterozoic bituminous sandstone, eastern Yanshan Region. Sci. China Ser. B 34, 479-489. 

Wang T.-G. and Simoneit B. R. T. (1995) Tricyclic terpanes in Precambrian bituminous sandstone from the eastern Yanshan region, North China. Chem. Geol. 120, 155-170. 

Fig. 6. Acyclic alkane, hopane and tetracyclic alkane cross plots of end member oils A and B and mixtures of each. Red squares are selected end member oils red circles represent calculated mixtures of oils A and B in 10% increments. Definition of ratios %35ab= 100 x S R C35 homohopane/(S R C34 homohopane + S R C35 homohopane) %24/4= 100 x C24 tetracyclic terpane/(C24 tetracyclic terpane + C23 tricyclic and C25 tricyclic terpane). Note that for the acyclic alkanes which have similar concentration ranges the mixing curve is essentially linear, whereas for the cyclic biomarkers with very different end member concentrations, the mixing curve is distinctively nonlinear. In this illustrative case of course the actual variations in %24/4 are not sensibly interpretable.

C23-C29 tricyclic terpanes/C3o a/3-hopane (modified from Mello et al. 1988)... 

Sterane isomerization ratios indicate that the Assekaifaf, Dome, Hassi Messaoud, and Zemlet oil samples experienced thermal maturities near or past the peak of the oil window, while the Zarzaitine and Oued Zenani samples are less mature (Fig. 5). This interpretation is supported by terpane data, such as the Ts/(Ts + Tm) and tricyclics/(tricyclics + hopanes) ratios (Table 2), which are lower for the Zarzaitine and Oued Zenani samples than the other oil samples. Both of these terpane ratios depend partly on organic facies, but the data in the table suggest that maturity rather than source input is the main control on high tricyclic terpanes and Ts in these oil samples. 

FIGURE 10. 70 eV mass spectra of tricyclic diterpanes (C20 and C19) derived from abietic acid or pimaric acid, resins, of coals and high plants. Isolated from coal (a) abietane (b) flchtelite (c) norprimane (d) C2o-tricyclic terpane , (e) isocopalane ... 

Pepper AS (1992) Estimating the petroleum expulsion behavior of source roeks a novel quantitative approaeh. In Petroleum Migration. Fleet AJ, England WA (eds), Geol Soe London 59 9-31 Peters KE (2000) Petroleum tricyclic terpanes predicted physicochemieal behavior from molecular mechanics calculations. Org Geochem 31 497-507... 

The selected ion recording voltage (SIRV) programs are typically run at 1000 resolution, but occasionally higher resolutions are also used, for example, to resolve biphenyls from dibenzofurans. The MRM programs are typically run at 500 resolution. Other specific MRM programs are used to analyze tricyclic terpanes, methylsteranes, diamondoids, oleanane, and bicadi-nanes when needed. 

Other than rt-alkanes, pristane, phytane, and other isoprenoid alkanes that are present in abundance in unaltered oils and easily recognizable by GC and GC-MS analyses, most of the biomarker components are present in trace amounts. Among these, naphthenic hydrocarbons, including tricyclic terpanes, pentacyclic triterpanes, and steranes, have been studied most extensively because they carry more specific information on source and depositional environment than normal and isoprenoid alkanes [21]. 

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