25th International Meeting on Organic Geochemistry IMOG 2011

P-053
Sulfur-bound compounds in free and bound lipids of recent
sediment of continental type
Tatyana Cheshkova, Tatyana Sagachenko
Institute of Petroleum Chemistry SB RAS, Tomsk, Russian Federation (corresponding
author:chtv12@mail.ru)
In this work SC of polar fractions of free and bond
(hydrolyzed) lipids from the sediment of continental
type (Lake Tukhloye, West Siberia) have been
studied.
By literature data sulfur in OM structures of
recent sediment occurs as sulfide and/or polysulfide
bridges mainly in intermolecular bonds. Reductive
desulfurization on Ni-Raney is widely used to
characterize such sulfur-bond structures followed by
isolation and analysis of the products obtained [3]. We
carried out comparative analysis of the individual
composition of the saturated hydrocarbons (HC)
isolated by a method of liquid-adsorption
chromatography from non-polar compounds (fraction
A) and desulfurization product of polar compounds of
the lipids under study (fraction B). By the data of gasliquid
chromatography and chromatography-massspectrometry
bond-free (А) and sulfur-bond (B)
saturated HC in free and hydrolyzed lipids are
presented by normal (m/z 57) and isoprenoid (m/z
113) alkanes, steranic (m/z 217) and terpanic (m/z
191) structures.
In both lipid forms sulfur-bond alkanes differ from
bond-free ones by a lower portion of n-alkanes and a
higher portion of isoprenoids. Relative content of
phitane increases in the composition of sulfur-bond
isoprenoid and one observes the appearance of
phitene and 5-octadecen (С18:1). The determined
character of the distribution of acyclic HC proves an
earlier conclusion that sulfurization of isoprenoids
proceeds more active as compared with n-alkanes [3].
Besides the indicated compounds we determined 4methylheptadecan
in fraction B of the hydrolyzed
lipids. Its appearance can testify that SC of the bond
lipids contain alkyltiacyclane structures, which under
desulfurization conditions are destructed to form the
identified HC.
Chromatography-mass-spectrometry analysis of
fractions A and B of the both lipid forms demonstrated
that HC С27–С29 of configurations ���20R,S and
�ββ20R,S. are included into the composition of
steranes. Higher concentration of �ββ20R,S –
steranes is typical for the compounds of fraction A.
Fraction A of the hydrolyzed lipids has a lower portion
of low-molecular homologues. Fraction A of the
hydrolyzed lipids has a lower content of pregnane
(С21) and contains no 20-methylpregnan С22. Sulfurbond
HC (fraction B) of the both lipid forms were
determined to have the same composition of regular
steranes С27–С29, among which ���20R,S – steranes
predominate. The absence of low-molecular
homologues of С21,22 composition is a special feature
of fractions B in sterane HC. The data obtained
testify that high-molecular steranes of ���configuration
are the first to enter sulfurization
process.
HC of terpane series in fractions A of the both
lipid forms are presented by tricyclic (cheilanthanes),
tetracyclic and 17�21β(С29, С30, С31 S,R) pentacyclic
(hopanes) structures. Fraction A of the hydrolyzed
lipids contain no hopanes of biological form
17β(Н),21β(Н) of С29, С31 S,R composition and
moretane – 17β21�С30. Hopanes 17�21β(С32, С33
S,R) appear in the composition pentacyclic
hydrocarbons, while monosaturated 17�21βС30hop-
17-21-en disappears. Fraction B of the both lipid
forms contain the same types of terpane HC:
17β21�С27, 17β21βС29, 17�21βС30 and 17β21β(С31
С32 S,R). For free lipids their content in fraction B is
higher as compared with fraction A. The concentration
of pentacyclic structures increases mainly due to
homologues of biological form 17β(Н),21β(Н).
Fraction B of the hydrolyzed lipids contain no
cheilanthanes С20H36, C22H40 and C25H46, tetracyclic
terpanes, pentacyclic HC 17�21βС27, 17β21�С30,
17β21βС30 and 17�21βС31 S,R, and monosaturated
17�21βhop-28-30-enС29. Sulfur-bound HC of the
hydrolyzed lipids differ from HC of fraction A by the
appearance of homologues of biological form
17β21β(С31,С32S,R). Biological β-hopanes are
characterized by thermodynamic instability
determining their participation in the processes of
sulfurization of lipid substances.
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