Octanol–air partition coefficients of polybrominated biphenyls

The octanol–air partition coefficients ( K OA) for PBB15, PBB26, PBB31, PBB49, PBB103 and PBB153 were determined as a function of temperature using a gas chromatographic retention time technique with 1,1,1-trichloro-2,2-bis (4-chlorophenyl) ethane (p,p′-DDT) as a reference substance. The internal energies of phase change from octanol to air ( Δ OA U) were calculated for the six compounds and were in the range from 74 to 116 kJ mol −1. Simple regression equations of log K OA versus relative retention times (RRTs) on gas chromatography (GC), and log K OA versus molecular connectivity indexes (MCI) were obtained, for which the correlation coefficients ( r 2) were greater than 0.985 at 283.15 K and 298.15 K. Thus the K OA values of the remaining PBBs can be predicted by using their RRTs and MCI according to these relationships.