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

- The KOA values for 14 OPFRs were determined by GC retention time method.
- Substitution pattern and VM were found to be capable of influencing log KOA-GC values of OPFRs.
- Log KOA-GC values of the remaining OPFRs can be predicted by using their RRTs.

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 (KOA) 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 KOA-GC values and internal energies of phase transfer (ΔOAU/kJ mol−1) ranged from 8.03 to 13.0 and from 69.7 to 149, respectively. Substitution pattern and molar volume (VM) were found to be capable of influencing log KOA-GC values of OPFRs. The halogenated alkyl-OPFRs had higher log KOA-GC values than aryl- or alkyl-OPFRs. The bigger the molar volume was, the greater the log KOA-GC values increased. In addition, a predicted model of log KOA-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 KOA-GC values of the remaining OPFRs can be predicted by using their RRTs on different GC columns.