Chlorines Are Not Evenly Substituted in Chlorinated Paraffins: A Predicted NMR Pattern Matching Framework for...

Area of Science:

• Environmental Chemistry
• Analytical Chemistry
• Organic Chemistry

Background:

• Chlorinated paraffins (CPs) are complex mixtures with numerous isomers, hindering environmental impact assessment.
• Existing analytical methods struggle to fully characterize CP isomer composition.

Purpose of the Study:

• To determine the isomeric distributions of C14/15 chlorinated paraffin mixtures.
• To develop and validate a novel computational approach for analyzing complex CP mixtures.

Main Methods:

• High-resolution mass spectrometry (MS) for molar distribution analysis.
• 1D and 2D nuclear magnetic resonance (NMR) spectroscopy.
• A new NMR spectral matching approach using neural network-predicted databases to identify top structural isomers.

Main Results:

• The study successfully characterized the isomeric distributions of nine CP mixtures.
• Chlorine distribution was found to be non-uniform, with a preference for the third carbon position.
• The developed NMR spectral matching approach provided an adequate representation of the complex mixtures.

Conclusions:

• The novel NMR spectral matching approach is effective for analyzing complex isomeric mixtures like CPs, which are difficult to resolve by MS alone.
• Understanding CP isomer composition is vital for accurate environmental and toxicological assessments.