Congener-specific partition properties of chlorinated paraffins evaluated with COSMOtherm and gas chromatographic retention indices

Jort Hammer,Hidenori Matsukami,Satoshi Endo

doi:10.1038/s41598-021-84040-z

Jort Hammer, Hidenori Matsukami + Show 1 more

Open Access

https://doi.org/10.1038/s41598-021-84040-z

Copy DOI

Abstract

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 25 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.

Highlights

Chlorinated Paraffins (CPs) are high volume production chemicals and have been found in various organisms including humans and in environmental samples from remote regions
Inspection of retention indexes (RIs) values of CPs from gas chromatographic (GC) columns with different polarity shows that the chlorination pattern plays an important role in determining polar interactions of CPs
Determining poly-parameter linear free energy relationship (ppLFER) descriptors for CPs shows that polarity differs significantly between CP chlorination patterns and confirm the importance of Cl positioning to the H-bond donating properties (A) of CPs

Summary

Introduction

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 of great importance to understand the physical–chemical properties of CPs. In this study, gas chromatographic (GC) retention indexes (RIs) of 25 CP congeners were measured on various polar and nonpolar columns to investigate the relationships between the molecular structure and the partition properties. 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. Different GC column coatings were selected with a range of polarity to elucidate the polar interaction properties of CPs. The physico-chemical properties of CP congeners were evaluated by deriving poly-parameter linear free energy relationship (ppLFER) descriptors from the measured data. Because COSMOthermX requires only the molecular structure as input parameter, it could be a useful tool to predict partition properties of CP congeners with diverse structures

Objectives

Methods

Results

Conclusion