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Congener-Specific Partition Properties of Chlorinated Paraffins Evaluated with COSMOtherm and Gas Chromatographic Retention Indices

preprint
submitted on 03.08.2020 and posted on 04.08.2020 by Jort Hammer, Hidenori Matsukami, Satoshi Endo

Chlorinated Paraffins (CPs) are high volume production chemicals and have been found in various organisms including humans and in environmental samples from remote regions. It is thus of great importance to understand the physical-chemical properties of CPs. In this study, gas chromatographic (GC) retention indexes (RIs) of 26 CP congeners were measured on various polar and nonpolar columns to investigate the relationships between the molecular structure and the partition properties. Retention measurements show that analytical standards of individual CPs often contain several stereoisomers. RI values show that chlorination pattern have a large influence on the polarity of CPs. Single Cl substitutions (-CHCl-, -CH2Cl) generally increase polarity of CPs. However, many consecutive -CHCl- units (e.g., 1,2,3,4,5,6-C11Cl6) increase polarity less than expected from the total number of -CHCl- units. Polyparameter linear free energy relationship descriptors show that polarity difference between CP congeners can be explained by the H-bond donating properties of CPs. RI values of CP congeners were predicted using the quantum chemically based prediction tool COSMOthermX. Predicted RI values correlate well with the experimental data (R2, 0.975–0.995), indicating that COSMOthermX can be used to accurately predict the retention of CP congeners on GC columns.

Funding

Environmental Restoration and Conservation Agency, Japan

History

Email Address of Submitting Author

hammer.jort@nies.go.jp

Institution

National Institute for Environmental Studies (NIES)

Country

Japan

ORCID For Submitting Author

0000-0002-1403-2631

Declaration of Conflict of Interest

No conflict of interest

Version Notes

Version 1.0 (3rd of August 2020)

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