Tissue to air partition coefficient for nonane and its isomers

Abstract

JP-8, a major fuel source used by US and NATO forces, is a complex mixture of aliphatic and aromatic isomers of hydrocarbons. Occupational exposure to JP-8 occurs through inhalation and dermal contact. Tissue/blood partition coefficients (PC) values are chemical specific parameters used in modeling. 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. PCs were first determined by vial equilibration methods developed by Sato and Nakajima (1979) and later modified by Gargas et al. (1989). PC values were obtained for five isomers of n-alkane nonane (C9), namely 3-methyloctane, 4-ethylheptane, 2,3-dimethylheptane, 2,2,4-trimethylhexane and 2,2,4,4-tetramethylpentane and n-nonane. The PC values tend to follow the published log octanol/water (O:W) PC values for n-nonane and its isomers. Experimentally determined PC values for n-nonane with the highest O:W ratio were greatest and the isomer 2,2,4,4- tetramethylpentane with the lowest O:W was the lowest. As expected fat tissue had the highest PC values for n-nonane and the isomers and muscle tissue the least. These reported PCs support the development of a jet fuel Physiologically Based Pharmacokinetic (PBPK) model.