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Mid infrared spectroscopy applications using quantum cascade lasers for the identification of microplastic contaminants in aqueous solution

2024 1 citation ? Citation count from OpenAlex, updated daily. May differ slightly from the publisher's own count.
H. Ted Stinson, Jason Sorger, Eric B. Takeuchi, T. Stathopoulos, Matthew Mitchell

Summary

Researchers reviewed the application of quantum cascade laser-based mid-infrared spectroscopy for identifying and quantifying microplastic contaminants in aqueous solution, examining how standalone compact laser sources, packaged liquid-phase spectrometers, and mid-IR microscopes can detect and classify individual plastic particles by their vibrational spectral signatures.

Quantum Cascade Lasers (QCLs) provide a high-power, tunable source of coherent light at wavelengths from 3-12 microns. Light in this band excites vibrational modes of many molecules of interest across widely diverse fields of interest. Spectroscopic instruments using QCLs have the capability to make breakthrough observations across multiple disciplines. We discuss the technical capability of these laser sources as well as their instrumentalized imaging and liquid-phase detection systems. We review the recent applications of QCL-based spectroscopy using standalone compact laser sources, packaged liquid-phase spectrometers, and mid-IR microscopes. In particular, we focus on a recent application of QCL-based IR microscopes to quantify microplastics in water and identify the plastic type of each particle using hyperspectral imaging. We show that QCL-based IR hyperspectral imaging can detect particles <20 um in diameter and can differentiate between different plastic materials with high accuracy.

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