Biomarker focus 36 - C30 Hopanes

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Occurrence and origin:

The C30 hopane isomers are normally the most common hopanes of sedimentary matter. The origin of the

hopanes is the most abundant hopanoid in prokaryotes, C35 tetrahydroxybacteriohopane.

	Cat. No. 0132,30 17α(H),21β(H)-Hopane (30αβ)

Geochemical relevance and use in oil spill analysis

Hopanes play an important role in geochemical investigations,1 and are diagnostic biomarker indicators and useful as proof of the origin in oil spill analysis2,3, oil waste analysis and analysis of airborne particulates. They contribute to the so-called terpane fingerprint and are commonly used to relate oils with source rocks.1

There are 4 common isomers of C30-hopanes. The most common are isomers with variable stereochemistry at the 17 and 21 positions, either β(H) with hydrogen above the plane or α-(H) with the hydrogen below the plane.

The natural isomer ββ (17β(H),21β(H)) may be found in recent sediments. However, the  αβ-isomer is always the dominant in mature sediments, while smaller amounts of the  βα- isomer are present. Only minor quantities of the less stable  αα-isomer are present. Thus, the ββ- and the αα-isomers are useful internal standards as they normally do not co-elute with other hopanes or triterpenoids in mature sediment.

The βα-isomers (moretanes) are highly specific for immature to early oil generation. The moretanes are thermally less stable than the  αβ-hopanes, and abundances of the C29 and C30 moretanes decrease relatively to the corresponding hopanes with thermal maturity. The ratio of  βα-moretanes to their corresponding αβ-hopanes decrease with thermal maturity from ca 0,8 to <0,15. The moretane/hopane ratio is used most commonly for C30, but it is also quantified using C29.

In fresh oil spills, the αβ-isomer of hopane is considered to be non-biodegradable and conserved. Consequently, it can be used as an internal standard to monitor the amount of total oil removed by bioremediation (treatment by oil-degrading bacteria).1

The hopanes elute on a normal unpolar GC-column in the order;  αβ-, βα-, αα-, ββ.  The C30 gammacerane (Cat. No. 2646.30) elutes late and in the region between the C31 22R (1339.31) and C32 22S (1338.31)isomers while the oleanane isomers ( α and β, Cat. No. 0617.30 and 0618.30) co-elutes with lupane  between βα29  and αβ30.

Figure: GC-MS of Mona-2 Oil, Danish North Sea

(Courtesy of Peter Nytoft, GEUS, Denmark)

Regular C30 Hopanes available from Chiron:

- 10 µg quantities are supplied in convenient 300µL GC-vials for dilution to e.g. 50-100µg/mL

- 50 and 100 µg/mL are supplied in isooctane (1 mL vials)

- Quantities are measured relative to the intensity (TIC) of 30áâ hopane or by gravimetry

2888.30-50-IO              17a(H),21á(H)-Hopane                                  50 ug

0132.30-100-IO            17a(H),21b(H)-Hopane                                 100 ug

0612.30-100-IO            17b(H),21a(H)-Hopane (moretane)                100 ug            

0613.30-100-IO            17b(H),21b(H)-Hopane (hopane)                   100 ug            

Other C30 Hopanes

2179,30-50-IO             17a(H),21a (H)-30-Nor-29-methylhopane          50 ug

2262.30-50-IO             17a(H),21â(H)-30-Nor-29-methylhopane           50 ug

2886.30-5UG               17á(H)-30-Diahopane (D30)                              5 ug

2884.30-5UG               17â(H),21á(H)-22-Methyl-28-nor-spergulane       5 ug

Other C30 Triterpanes

2646.30-10UG   Gammacerane                                                          10 ug    

0617.30-100-IO 18á(H)-Oleanane                                                     100 ug

0618.30-100-IO 18â(H)-Oleanane                                                     100 ug

0619.30-100-IO Friedelane                                                               100 ug

0616.30-100-IO Lupane                                                                    100 ug

0620.30-100-IO Onocerane I                                                            100 ug

0621.30-100-IO Onocerane II                                                           100 ug

1192.30-100-IO 20R/20S-Dammarane                                               100 ug

Other relevant Biomarker Focus:

Norhopanes: Biomarker Focus 7

Rearranged hopanes: Biomarker Focus 35

2-Methyl and 3-Methylhopanes: Biomarker Focus 37

Homohopanes and gammacerane: Biomarker focus 38

References:

1.         Peters, Walters and Moldowan, The Biomarker Guide, Cambrigde University Press, Cambridge, 2005

3.         Daling, Faksness, Hansen, and Stout, Environmental Forensics, 2002; 3, 263  

            cf: http://www.nordicinnovation.net/nordtestfiler/tec498.pdf 

4.         Wang and Fingas, Marine Pollution Bulletin, 2003; 47, 423, and references therein

5.         Nytoft and Bojesen-Koefoed, Organic Geochemistry, 2001; 32, 841

6.         J.R. Brook et.al., Atmospheric environment, vol 41, issue 1, (20007) 119-135

7.         K.E.Peters, C.C. Walters and J.M. Moldowan, The biomarker guide, 2. ed. Vol. 1&2, Cambridge University Press, Cambrige 2005.