Intermolecular Interactions, Solute Descriptors, and Partition Properties of Neutral Per- and Polyfluoroalkyl...

Area of Science:

• Environmental Chemistry
• Chemical Thermodynamics

Background:

• Per- and polyfluoroalkyl substances (PFAS) are widespread environmental contaminants.
• Understanding their environmental partitioning is essential for assessing transport and fate.
• Data on PFAS partition coefficients are limited, hindering accurate environmental modeling.

Purpose of the Study:

• To determine polyparameter linear free energy relationship (PP-LFER) solute descriptors for neutral PFAS.
• To predict partition coefficients between different environmental phases (octanol/water, air/water, octanol/air).
• To evaluate the accuracy of PP-LFER models and compare them with quantum chemical predictions.

Main Methods:

• Measured isothermal gas chromatographic (GC) retention times for 60 neutral PFAS using varied polarity columns.
• Combined GC data with new and existing octanol/water partition coefficient data.
• Developed PP-LFER models to derive solute descriptors and predict partition coefficients.
• Validated PP-LFER predictions against the COSMOtherm model.

Main Results:

• Obtained a complete set of solute descriptors for 47 PFAS, characterizing their intermolecular interactions.
• PP-LFER models accurately predicted partition coefficients, showing good agreement with COSMOtherm.
• Generated a chemical partitioning space plot illustrating environmental distribution drivers.
• Demonstrated the air phase's primary role in distributing nonpolar/weakly polar PFAS.

Conclusions:

• PP-LFER models are highly accurate for predicting partition properties of neutral PFAS.
• These models effectively fill critical data gaps in PFAS environmental partitioning.
• Environmental distribution of PFAS is influenced by polarity, with air and organic phases playing significant roles.