1. Marine Science Institute, The University of Texas at Austin
Overview of petroleum hydrocarbon analysis: Some insights from Deepwater Horizon oil spill
Zhanfei Liu
Marine Science Institute, The University of Texas at Austin
Liu Lab
Dr. Hernando Basosa, postdoc
Meredith Evans, MS ( )
Qing Wang, visiting PhD student ( )
Jiqing Liu, lab technician ( )
R/V Pelican
February 14, 2017

2. How can we better understand, respond to and mitigate the threats of petroleum pollution?
Species & Ecosystem Effects
Environmental Remediation
Petroleum Chemistry
Oil
Transport & Weathering
Human Impacts

3. Chemical Composition of Crude Oil

4. Chemical Composition of Crude Oil
75% Aliphatic Hydrocarbons
Simple Molecular Structure
Relatively non-toxic

5. Chemical Composition of Crude Oil
15% Aromatic Hydrocarbons
75% Aliphatic Hydrocarbons
Alkanes
Alkenes
Cycloalkanes
Complex Molecular Structure
High Toxicity

6. Chemical Composition of Crude Oil
10% Resins & Asphaltenes
15% Aromatic Hydrocarbons
Polycyclic Aromatic Hydrocarbons (PAHs)
Alkylated PAHs
High Toxicity
75% Aliphatic Hydrocarbons
Alkanes
Alkenes
Cycloalkanes
Used to trace oil spills
Low Toxicity

7. Petroleum Chemistry - it’s Complicated
Wave action
Bacterial degradation
Evaporation
Dissolution
Sunlight O O O
The unfortunate thing about petroleum chemistry, is that it’s complicated
So I would argue that what we really need in order to make this less complicated is method expansion.
Because… only ~25% GC-amenable
Other people are doing method expansion too
I’ll go over a method application we’re using O

8. In situ detection based on the fluorescence of oil
CTD
(Camilli et al., 2010, Science)

9. The traditional way of analyzing the chemical composition
Hexane/benzene fraction; Gas Chromatography –
Mass Spectrometry
(16 priority EPA PAHs &
Alkylated PAHs)
Hexane fraction; Gas Chromatography –
Flame Ionization Detector
(C8 – C40 alkanes)

10. Gas Chromatography-Mass Spectrometry (aromatic fractions or fingerprinting)
The 2014 Houston Ship Channel oil spill
(Bacosa et al., 2016, Mar. Poll. Bull.)

11. Gas chromatography-Flame Ionization Detection
Saturated hydrocarbons such as n-alkanes; TPH

12. Quantifying n-alkanes by GC-FID
(UCM)Unresolved complex mixture

13. A significant amount of oxygenated hydrocarbons was formed in surface oil slicks and sandy patties after the DWH oil spill.
(Aeppli et al., 2012, Environ. Sci. Technol.)

14. GCXGC-FID
(Aeppli et al, 2014, Environ. Sci. Technol.)

15. Fourier transform ion cyclotron mass spectrometry (FTICR-MS)
(McKenna et al., 2013, Environ. Sci. Technol.)

16. (Chen et al., 2016, Environ. Sci. Technol.)

17. Fingerprint oil source Quantify hydrocarbons
This technique is fast, efficient, without pretreatment, in need of a very small sample size, and can:
Fingerprint oil source
Quantify hydrocarbons
Provide insights into structural info of weathered oil
So how did we get to this data? Is this hard to come by? Current methods, method drawbacks, expanding methods
(Evans et al, Environ. Sci. Technol., in revision)

18. Ramped Pyrolysis – Gas Chromatography – Mass Spectrometry with Thermal Slicing
Quantification Zone
Cracking Zone

19. Thermal Slicing Py-GC-MS: Crude Oil
Quantification Zone
C31
C12
C13
C14
C15
C16
C17
C25
C18
C20
C19
C21
C22
C23
C24
C30
C26
C27
C28
C29
C32
C33
Now that you’ve seen how this technique works, I want to walk you though how we can apply it to simplify petroleum weathering, using samples we’ve collected from the DWH spill.
Cracking isn’t seen until the 5th range, so we can use these slices for quantification.
*5.5 minute peak = internal standard

20. 337 d Tar - High Temperature
Thermal Slicing Py-GC-MS: Structure Zone
337 d Tar - High Temperature
Structure Zone
Now that you’ve seen how this technique works, I want to walk you though how we can apply it to simplify petroleum weathering, using samples we’ve collected from the DWH spill.
Cracking isn’t seen until the 5th range, so we can use these slices for quantification.

21. Detected n-alkanes and aromatics in the cracking zone (370-650C)
(Evans et al., EST, in revision)

22. The new Agilent HPLC-ion mobility (IM)-Quadrupole-Time-of-Flight system (ERC 3rd floor)

23. (From Agilent)

24. Take home message
A further understanding of the oil spill in marine environments relies on the development of analytical instruments.
From the Deepwater Horizon oil spill, both ultrahigh resolution MS and pyrolysis GC-MS showed promise in deciphering structures of petroleum hydrocarbons.