Advanced Spectroscopy Techniques Improve Microplastics Identification and Characterization

Advanced Spectroscopy Techniques Improve Microplastics Identification and Characterization © weerasak -chronicles-stock.adobe.com

Introduction
Microplastics (MPs), tiny plastic particles measuring less than 5 millimeters, pose growing concerns due to their pervasive presence in the environment and potential impacts on ecosystems and human health. Accurately identifying and characterizing these particles is essential for understanding their sources, fate, and effects. Traditional single-technique approaches can struggle with complex mixtures and overlapping signals, limiting reliable detection (1).

In a new study published in Anais da Academia Brasileira de Ciências, Ramos and Dias (1) present a refined analytical method that integrates infrared (FT-IR) and Raman spectroscopy to improve microplastic identification. The research was conducted by V.S. Ramos and M.L. Dias at Brazilian institutions specializing in analytical chemistry and environmental sciences. Their contribution adds valuable tools for ongoing efforts to understand and manage microplastic pollution globally (1).

Microplastics are now detected in diverse environments ranging from ocean sediments to atmospheric dust, reflecting the persistence and widespread dispersal of synthetic polymers in the biosphere (1,2). Their small size facilitates ingestion by a wide variety of organisms, from plankton to higher trophic-level species, with potential implications for food web dynamics and human exposure (2). Detecting and identifying these particles in heterogeneous samples remains a major analytical challenge, as microplastics often coexist with natural particulates, organic matter, and chemical residues that can mask or distort spectroscopic signatures (1–3).

Advances in vibrational spectroscopy offer promising avenues for overcoming these obstacles. By refining acquisition protocols, applying robust chemometric models, and integrating complementary techniques, researchers can improve both the specificity and sensitivity of microplastic detection (1,3). The study by Ramos and Dias builds upon this momentum, presenting a dual-technique methodology that not only strengthens polymer identification but also addresses key analytical bottlenecks, such as spectral interference and degradation-induced signal loss. Their work demonstrates how careful methodological integration can transform spectroscopic data into reliable, actionable information for environmental monitoring and policy-making (1).

Enhanced Spectroscopic Approach for Microplastic Analysis
Building on this context, the research by Ramos and Dias leverages the complementary strengths of two vibrational spectroscopy techniques: infrared and Raman spectroscopy. Infrared spectroscopy measures molecular vibrations based on light absorption, revealing functional groups within polymers (1–3). Raman spectroscopy, on the other hand, detects inelastic scattering of light, providing distinctive molecular fingerprints. By combining these methods, the researchers aim to overcome limitations encountered when using either technique alone (1).

Addressing Challenges in Spectral Overlap and Interference

One key challenge in microplastic analysis is the presence of overlapping spectral features from environmental contaminants or mixed polymer samples. The authors introduce advanced data processing strategies that deconvolute overlapping signals, allowing clearer differentiation of polymer types. This refinement enhances identification accuracy, particularly for complex samples where multiple plastic types coexist or are partially degraded (1).

Methodological Details and Findings

Ramos and Dias applied their integrated infrared and Raman spectroscopic protocol to a wide range of microplastic samples representative of common environmental pollutants. They optimized spectral acquisition parameters to maximize signal quality and minimize noise. Their approach successfully distinguished polymers such as polypropylene (PP), low-density polyethylene (LDPE), polystyrene (PS), and polyvinyl chloride (PVC), even in mixed or weathered states (1).

The study emphasizes how the spectral information from both techniques complement one another: infrared spectroscopy provides robust identification of chemical bonds, while Raman spectroscopy contributes detailed structural insights. This synergy leads to a more comprehensive characterization than either method alone can offer (1).

Implications for Environmental Monitoring

The refined spectroscopic method has practical implications for environmental science, particularly in monitoring microplastic pollution in water, soil, and biota. Accurate polymer identification aids in tracing pollution sources, assessing degradation pathways, and evaluating ecological risks. The approach can be adapted to portable field instruments, enhancing real-time monitoring capabilities (1).

References
(1) Ramos, V. S.; Dias, M. L. Refined Analysis of Microplastics: Integrating Infrared and Raman Spectroscopy. An. Acad. Bras. Ciênc. 2025, 97 (Suppl. 3), e20241313. DOI: 10.1590/0001-3765202520241313

(2) Choudhury, T. R.; Riad, S.; Uddin, F. J.; Maksud, M. A.; Alam, M. A.; Chowdhury, A. S.; Mubin, A. N.; Islam, A. R. M. T.; Malafaia, G. Microplastics in Multi-Environmental Compartments: Research Advances, Media, and Global Management Scenarios. J. Contam. Hydrol. 2024, 265, 104379. DOI: 10.1016/j.jconhyd.2024.104379

(3) Wetzel, W. FT-IR Spectroscopy for Microplastic Classification. Spectroscopy 2024, Dec 19. Available at: https://www.spectroscopyonline.com/view/ft-ir-spectroscopy-for-microplastic-classification (accessed 2025-08-12).