Novel Hydrophobicity Ruler Approach for Determining the Octanol/Water Partition Coefficients of Very Hydrophobic Compounds via Their Polymer/Solvent Solution Distribution Coefficients

Abstract

A novel hydrophobicity ruler approach for determining the octanol/water partition coefficients of very hydrophobic compounds is proposed, which is an indirect method that measures the polymer/solvent solution distribution coefficients (log Kp/s) of reference and unknown compounds. The log Kp/s values of the unknown compounds can be calibrated to their log Ko/w values via the correlation of the log Kp/s values of the reference compounds with their log Ko/w values. An organic solvent was used to increase the solubility of the very hydrophobic compounds in the aqueous solution, so that their concentrations and absorption amounts were high enough to be measured precisely. The solvent also reduced the hydrophobicity scale of the very hydrophobic compounds and controlled the amounts absorbed into the polymer phase, so that compounds spanning a very wide range of log Ko/w values could be measured in a single measurement and the coexisting compounds would not interfere each other. Poly(dimethylsiloxane) (PDMS), aqueous methanol solutions, and a series of 21 PCB (polychlorinated biphenyl) compounds were used to demonstrate the principle of the hydrophobicity ruler approach. The PCB compounds with known experimental log Ko/w values served as reference compounds, whereas the PCB compounds without known log Ko/w values were determined. The log Ko/w values determined for PCB126, PCB187, PCB197, PCB180, PCB170, and PCB195 were 6.94, 7.84, 8.33, 8.17, 7.92, and 8.49, respectively. The correlation of the log Kp/s values of the reference PCB compounds with their log Ko/w values was linear (log Ko/w=2.56 log Kp/s+1.08, R2=0.95). The hydrophobicity ruler approach is also a valuable tool for validating the experimental and theoretical log Ko/w values and identifying outliers in log Ko/w databases.

First Report on In Vivo Pharmacokinetics and Biotransformation of Chlorinated Polyfluoroalkyl Ether Sulfonates in Rainbow Trout

“…Due to the similar reasons, the smaller sized and less hydrophobic 6:2 H-PFESA was more accumulated in blood than its 8:2 counterpart. The relative hydrophobicity between Cl-PFESA and H-PFESAs was evaluated by their retention times on the C18 UPLC column, which were 7.15 min for 6:2 Cl-PFESA versus 6.44 min for 6:2 H-PFESA, and 7.73 min for 8:2 Cl-PFESA versus 7.09 min for 8:2 H-PFESA (Figure S1). The obtained results indicate that H-PFESAs are less hydrophobic than Cl-PFESAs, and 6:2 H-PFESA is less hydrophobic than 8:2 H-PFESA.…”

Fluorescence based detection of polychlorinated biphenyls (PCBs) in water using hydrophobic interactions

“…24 27 As non-planar PCB gave the highest intensity and has high hydrophobicity based on the number of chlorine atoms it is likely that PCB 206 will result in the greatest fluorescence increase as it has a log K ow 10.83. 27 For comparison, figure 4(d) demonstrates the interaction of BaP with humic acid (H.A), biphenyl (BiP) and 4, 4-Dihydroxy biphenyl (Di-OH BiP). BiP and Di-OH BiP molecules were selected due to their PCB like structure, hydrophobic nature and absence of chlorine atoms.…”

Larval Exposure to Polychlorinated Biphenyl‐126 Led to a Long‐Lasting Decrease in Immune Function in Postmetamorphic Juvenile Northern Leopard Frogs, Lithobates pipiens

“…The PCBs are lipophilic compounds with high octanol–water partition coefficients ( K OW PCB‐126 = 6.94; Kong et al, 2005). Because PCBs are readily detected in sediments and biota and less so in dissolved and/or particulate aquatic phases (DeVault et al, 1996; Fisk et al, 1998), we used dietary exposure to better mimic the primary ecological exposure route.…”