High-resolution NMR spectroscopic approaches to quantify PET microplastics pollution in environmental freshwater...

Area of Science:

• Environmental Science
• Analytical Chemistry
• Polymer Science

Background:

• Microplastic pollution, particularly polyethylene terephthalate (PET), poses a significant threat to ecosystems.
• Accurate identification and quantification methods are crucial for understanding microplastic impacts.
• Existing methods for microplastic detection often face limitations in particle size independence and detailed polymeric analysis.

Purpose of the Study:

• To develop and validate a workflow for the precise identification and quantification of PET microplastics in environmental surface waters.
• To utilize high-resolution nuclear magnetic resonance (NMR) spectroscopy for microplastic analysis.
• To provide insights into the polymeric characteristics of detected PET microplastics.

Main Methods:

• Application of high-resolution NMR spectroscopy for PET detection and quantification.
• Filtration of surface water samples using Manta trawls.
• Extraction and dissolution of filtered samples for NMR analysis.
• Monitoring of translational diffusion and relaxation properties of PET chains.

Main Results:

• Achieved a limit of detection of 192.2 ng PET.
• Demonstrated a recovery rate of 88 ± 25% for spiked PET microplastics.
• Determined PET concentration in Lake Constance water to be 335 ± 200 ng/m³.
• Revealed a heterogeneous distribution in the length of PET chains.

Conclusions:

• The developed NMR-based workflow enables unambiguous identification and precise quantification of PET microplastics, independent of particle size.
• This method offers insights into inherent polymeric features not accessible by other techniques.
• The workflow presents a simple, reliable, and broadly applicable approach for environmental microplastic monitoring.