Toxicology mechanisms and methods

Partition coefficients for nonane and its isomers in the rat.

PMID 20919799


Jet Fuel 8 (JP-8) is a major fuel source used by US and NATO military. JP-8 is a complex mixture of aliphatic and aromatic isomers of hydrocarbons. Tissue/blood partition coefficient (PC) values are chemical-specific parameters used in modeling the kinetic behavior of chemicals. The partition coefficient values for n-alkanes tend to increase with the increasing carbon number, but less is known about the trend for isomers of n-alkanes. PC values were obtained for the n-alkane nonane (C9) and five of its isomers, namely 3-methyloctane, 4-ethylheptane, 2,3-dimethylheptane, 2,2,4-trimethylhexane, 2,2,4,4-tetramethylpentane. The blood:air and tissue:air PC values correlated with the published log octanol/water (O:W) PC values for n-nonane and its isomers. Experimentally determined blood:air and tissue:air PC values for n-nonane with the largest O:W value were greatest and smallest for the isomer 2,2,4,4-tetramethylpentane with the lowest O:W value. As expected the fat tissue had the highest PC values and muscle the lowest for n-nonane and its isomers. For each tissue, a linear relationship was observed between the tissue/blood PC values for the isomers of n-nonane and n-nonane. This suggests that tissue/blood PC values for all isomers of an alkane could be estimated using data collected from only a sub-set of alkanes of equal carbon number. These reported tissue/blood PC values will support the development of a jet fuel physiologically-based pharmacokinetic (PBPK) model.

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