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

The octanol-air partition coefficient (KOA) 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 KOA 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 (ΔOAU) 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 KOA of OH/MeO-PBDE congeners was developed based on the 16 fundamental quantum chemical descriptors computed by PM3 Hamiltonian, for which the Qcum2 was about 0.937. The molecular weight (Mw) and energy of the lowest unoccupied molecular orbital (ELUMO) were found to be main factors governing the log KOA.