Hopane
Definition
A class of pentacyclic triterpane biomarker compounds (C27-C35) in petroleum, derived from bacteriohopanetetrol in ancient sedimentary organic matter. C30 17alpha,21beta-hopane is the most weathering-resistant compound in most crude oils and is used as the internal normalisation standard in oil-spill source attribution.
- Compound class
- Pentacyclic triterpanes, C27-C35
- Origin
- Bacteriohopanetetrol in ancient sedimentary matter
- Key marker
- C30 17alpha,21beta-hopane
- Forensic use
- Internal normalisation standard in oil-spill attribution
Common questions
Why is C30 17alpha,21beta-hopane chosen as the normalisation standard rather than another compound?+
It resists weathering, evaporation, and biodegradation more than most other petroleum components, so its concentration stays relatively stable over time, allowing other compound ratios to be normalised against it for reliable source comparison even in a weathered spill.
How does hopane analysis actually link a spill to its source?+
Analysts compare the ratio pattern of multiple hopane and related biomarker compounds between the spilled oil and candidate source oils, since these ratios act as a chemical fingerprint largely unaffected by the evaporative and biodegradation losses that alter lighter hydrocarbons.
Related terms
- Aroclor
- A series of polychlorinated biphenyl (PCB) commercial mixtures manufactured by Monsanto (US) and marketed as electrical insulating fluids. Aroclors are designated by...
- C30 17Alpha-Hopane
- The C30 pentacyclic triterpane used as the primary internal normalisation standard in petroleum biomarker fingerprinting. It is resistant to evaporation, biodegradation, and...
- Dissolved Gas Analysis (DGA)
- The analysis of gases dissolved in transformer oil (H2, CH4, C2H4, C2H2, CO, CO2) by ASTM D3612 or IEC 60599 to diagnose...
- GC-IRMS
- Gas chromatography isotope ratio mass spectrometry: compounds separated by GC are combusted (for 13C) or pyrolysed (for 2H) and the isotope ratio...
- GC×GC-TOFMS
- Two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (Leco Pegasus instruments). The first GC column separates by boiling point; a cryogenic modulator...
- Karl Fischer Titration (KFT)
- Coulometric or volumetric titration using Karl Fischer reagent (iodine / sulphur dioxide / base / methanol) that reacts stoichiometrically with water. Used...
- SAE Viscosity Grade
- The Society of Automotive Engineers (SAE J300) classification of motor oil viscosity: the 'W' number specifies low-temperature cranking viscosity; the trailing number...
- Unresolved Complex Mixture (UCM)
- The broad hump of hundreds of co-eluting cycloalkane and isoalkane compounds in the TIC of heavy petroleum products (diesel, heavy fuel oil,...
- Zinc Dialkyldithiophosphate (ZDTP)
- The primary anti-wear additive in motor oils, contributing zinc, phosphorus, and sulphur to the additive package. The Zn/P ratio and S/P ratio...