Determination and prediction of octanol–air partition coefficients of hydroxylated and methoxylated polybrominated diphenyl ethers

Abstract

The octanol–air partition coefficient ( K OA) of 19 hydroxylated polybrominated diphenyl ethers (OH-PBDEs) and 10 methoxylated polybrominated diphenyl ethers (MeO-PBDEs) were measured as a function of temperature using a gas chromatographic retention time technique. At room temperature (298.15 K), log K OA ranged from 8.30 for monobrominated OH/MeO-PBDEs to 13.29 for hexabrominated OH/MeO-PBDEs. The internal energies of phase change from octanol to air (Δ OA U) for 29 OH/MeO-PBDE congeners ranged from 72 to 126 kJ mol −1. Using partial least-squares (PLS) analysis, a statistically quantitative structure–property relationship (QSPR) model for log K OA of OH/MeO-PBDE congeners was developed based on the 16 fundamental quantum chemical descriptors computed by PM3 Hamiltonian, for which the Q cum 2 was about 0.937. The molecular weight ( Mw) and energy of the lowest unoccupied molecular orbital ( E LUMO) were found to be main factors governing the log K OA.