Nome Completo: Ana Valéria Colnaghi Simionato

Sociedade Brasileira de Espectrometria de Massas – BrMASS
Hiphenated Techniques
Characterization of sterane and hopane biomarkers in tar sands
by Gas Chromatography-Triple Quadrupole Mass Spectrometry
Laercio Lopes Martins (PG)1, Bárbara Diniz Lima (PG)1, Georgiana Feitosa da
Cruz (PQ)1*, Alexsandro Araujo da Silva (PQ)2, Carlos Alberto da Silva Riehl
(PQ)3
*[email protected]
1
State University of North Fluminense, Petroleum Engineering and
Exploration (LENEP/UENF), Macaé-RJ, Brazil.
2
State University of Rio de Janeiro, Chemistry Institute, Central Analítica
Fernanda Coutinho, Rio de Janeiro-RJ, Brazil.
3
Federal University of Rio de Janeiro, Chemistry Institute, LEMA, Rio de
Janeiro-RJ, Brazil.
There are tar accumulations in Lower Triassic sandstones along the eastern
margin of the Paraná Basin (São Paulo State). These tar sands are sandstones
impregnated with heavy oil (severely biodegraded oil) derived from black shale of Irati
Formation (source rock) that matured along the basic sills of the Serra Geral continent
flood basalt cover1. The eolic tar sands from Pirambóia are the reservoir rock that has
been studied by Chang-Caetano (1997)2, and four sedimentary facies were observed:
Dry Interdune, Wet Interdune, Dune Bottomset and Dune Foreset.
Sterane and hopane biomarkers are often used to help describe organic facies,
determine maturity of oils and extracts, and correlate oils with each other or with rock
source3. Failures in correlations are usually due to low biomarker concentrations, lack
of distinguishing characteristics in the biomarker distributions, or extreme
biodegradation, such as these tar sands4. The relative stability of steranes and hopanes
during biodegradation makes them useful in correlating somewhat biodegraded
samples. However, due to the complexity of this compounds in geochemistry samples,
they coelute when analyzed only by HRGC-SQ-MS, that difficult to calculate biomarkers
paramaters. In front of this, the samples was analyzed by HRGC-TQ-MS using MRM
technique (precursor ion – product ion) that provide high selectivity allowing the
detection of steranes and hopanes, even in trace levels not detected by SQ-MS.
As a results, the transitions in MRM technique for steranes (m/z 372 + 14n, n =
0 a 2  m/z 217) and hopanes (m/z 370 + 14n, n = 0 a 8  m/z 191) improved the
evaluation of biodegradation degree in tar sand samples, confirming the correlation
between geochemical composition of oil and the sedimentary facies.
References
[1] Araújo, C.C.; Yamamoto, J.K.; Rostirolla, S.P.; Madrucci, V.; Tankard, A. Mar. Petrol. Geol.
2005, 22, 671-685.
[2] Caetano-Chang, M. Tese de Doutorado - Instituto de Geociências e Ciências Exatas da
Universidade Estadual Paulista, Brasil, 1997.
[3] Waples, D. W.; Machihara, T. AAPG Bull. 1990, 38 , 357-380.
[4] Martins LL. Dissertação de Mestrado - Universidade Estadual do Norte Fluminense, Brasil,
2013.
5º Congresso BrMass – 7 a 11 de Dezembro de 2013