Determination and prediction of octanol-air partition coefficients for organophosphate flame retardants

Organophosphate flame retardants (OPFRs) have attracted wide concerns due to their toxicities and ubiquitous occurrence in the environment. In this work, Octanol-air partition coefficient (K_OA) for 14 OPFRs including 4 halogenated alkyl-, 5 aryl- and 5 alkyl-OPFRs, were estimated as a function of temperature using a gas chromatographic retention time (GC-RT) method. Their log K_OA-GC values and internal energies of phase transfer (Δ_OAU/kJmol^-1) ranged from 8.03 to 13.0 and from 69.7 to 149, respectively. Substitution pattern and molar volume (V_M) were found to be capable of influencing log K_OA-GC values of OPFRs. The halogenated alkyl-OPFRs had higher log K_OA-GC values than aryl- or alkyl-OPFRs. The bigger the molar volume was, the greater the log K_OA-GC values increased. In addition, a predicted model of log K_OA-GC versus different relative retention times (RRTs) was developed with a high cross-validated value (Q²_(cum)) of 0.951, indicating a good predictive ability and stability. Therefore, the log K_OA-GC values of the remaining OPFRs can be predicted by using their RRTs on different GC columns.