A Critical Review of Application of Quantum Cascade Laser Infrared Spectroscopy and Imaging in Microplastic Research

Microplastics (MPs) are small plastic particles (<5 mm) that pose significant risks to the environment and human health. Conventional analytical techniques for MP detection have inherent limitations that hinder comprehensive analysis. Quantum cascade laser infrared (QCL-IR) spectroscopy and imaging have emerged as an advanced technique for rapid, sensitive, and broad-spectrum analysis of MPs across diverse environments and sample types. This critical review explores QCL-IR applications in MP research, synthesizing insights reported to date. From a technical perspective, it highlights advantages and challenges such as discrete frequency infrared imaging and substrate selection (slides and filters), as well as limitations identified in the literature. Finally, recommendations are proposed to further refine this technique, enhancing its efficiency, accessibility, and applicability to future MP research.