Aromatic biomarkers and their
structural isomers have been found useful for the maturity assessment of oils, source rocks and coals (Radke et al, 1982a; Radke and Welte, 1983; Alexander et al, 1985; Radke et al., 1986; Garrigues et al, 1988; Strachan et al, 1988; Akaegbobi et al, 2000; Akinlua et al, 2007; Sonibare et al, 2008).
First, the vitamin B3 was found along with its
structural isomers -- related molecules that have the same chemical formula but whose atoms are attached in a different order.
Structural isomers of poly/fluorinated di-and tri-alkylated phosphate ester surfactants present in industrial blends and in microwave popcorn bags.
As expected the two
structural isomers having an atomic sequence HONO are more stable than the other possible tetra atomic combinations such as HOON or OONH that are far more unstable than the isomer having a central nitrogen atom.
This value is much larger than the band gaps of its
structural isomers PFDA and PPV.
Separation of the chloroform extract by column chromatography over silica gel allowed to isolate four mixtures of these triterpenes, each of them constituted of two
structural isomers 1-2, 3-4, 5-6, and 7-8, in the ratio ursane:oleanane derivatives 2:1.