Enhanced forensic discrimination of pollutants by position-specific isotope analysis using isotope ratio monitoring by 13C nuclear magnetic resonance spectrometry

• Isotope ratio monitoring by 13C NMR for a unique intramolecular isotope composition.
• Better inference of the pollution source by intramolecular 13C profiles.
• Contribution to environmental forensic studies.

In forensic environmental investigations the main issue concerns the inference of the original source of the pollutant for determining the liable party. Isotope measurements in geochemistry, combined with complimentary techniques for contaminant identification, have contributed significantly to source determination at polluted sites. In this work we have determined the intramolecular 13C profiles of several molecules well-known as pollutants. By giving additional analytical parameters, position-specific isotope analysis performed by isotope ratio monitoring by 13C nuclear magnetic resonance (irm-13C NMR) spectrometry gives new information to help in answering the major question: what is the origin of the detected contaminant? We have shown that isotope profiling of the core of a molecule reveals both the raw materials and the process used in its manufacture. It also can reveal processes occurring between the contamination site ‘source’ and the sampling site. Thus, irm-13C NMR is shown to be a very good complement to compound-specific isotope analysis currently performed by mass spectrometry for assessing polluted sites involving substantial spills of pollutant.

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