Analytical and Measuring Instruments for Microplastics

Significance of the Subject

Microplastics are pervasive marine pollutants (several µm to 5 mm) that threaten ecosystems through physical harm and chemical exposure. They carry additives and adsorbed toxins into the food chain, raising concerns for environmental and human health.

Objectives and Overview of the Study

This whitepaper surveys Shimadzu’s analytical and measurement solutions for microplastics research. It outlines end-to-end workflows—from environmental sampling and pretreatment to polymer identification, particle quantification, thermal analysis, and contaminant profiling—enabling tailored approaches for R&D, quality control, and ecological monitoring.

Methodology and Instrumentation

Sampling and Pretreatment

• Sources: seawater, river water, drinking water, marine organisms, wastewater carriers.
• Pretreatment steps: density separation, oxidative digestion, filtration, gravity separation, contaminant removal.

Analysis Techniques

• Non-destructive polymer ID: FTIR spectroscopy (IRTracer-100), infrared microscopy (AIM-9000), elemental analysis (EDX-8000).
• Particle metrics: dynamic particle image analysis (iSpect DIA-10) for size, shape, count concentration (particles/mL).
• Destructive bulk composition: pyrolysis GC/MS (Py-GCMS), DSC (DSC-60 Plus) for blend ratios and crystallinity.
• Contaminant analysis: GCMS-TQ8040 for PAHs, LCMS-8060 for PFAS; correlation of adsorption with hydrophobicity (Log Kow/Log D).
• Elemental coatings: XRF-1800, EDX-8000 for Cu in aquaculture net coatings; EPMA for additive mapping.

Main Results and Discussion

Polymer Identification

• Primary microplastics (e.g. scrub beads) identified as PS by microscopic IR transmission.
• Mapping of secondary fragments on filters revealed distributions of PE, PP, PET via infrared microspectroscopy.

Biota-Associated Particles

• Polar cod gut contents contained PMMA and kaolin; deepwater shrimp ingested PE, CaCO₃, kaolin, illustrating food chain transport.

Fishing Net Analysis

• Unused nets: PE and PP matrix with CaCO₃ and silicate fillers.
• Recycled nets: polyamides and cellulose; EDX quantification of Cu antifouling coatings (8–15 wt%).

Wastewater Treatment Carriers

• Plastic pellets: PE core with cellulose surface; no significant additive leaching after use.

Particle Metrics

• Environmental water contained ~5 300 particles/mL of 10–30 µm fragments and fibers.

Blend Ratio Determination

• DSC enthalpy calibration quantified LDPE/PP and HDPE/PP blends within a few percent of actual ratios.

Contaminant Adsorption

• PAHs and PFAS adsorb differentially to PP, PS, PE; adsorption correlates positively with hydrophobicity (Log Kow/Log D).

Benefits and Practical Applications

• Modular workflows address diverse research needs: qualitative ID, quantitative thermal analysis, particle imaging, and multi-residue contaminant profiling.
• Supports environmental monitoring, ecotoxicology, QA/QC of recycled plastics, and design of wastewater treatment media.

Future Trends and Opportunities

• High-throughput, automated image-chemical analysis for sub-300 µm particles.
• Advanced hyphenated techniques (GC-GC/MS, LC-MS-FTIR) for simultaneous polymer and contaminant characterization.
• Standardization of protocols and reference materials to harmonize global microplastic data.
• In situ and miniaturized sensing platforms for real-time ocean and drinking water microplastic monitoring.

Conclusion

Shimadzu’s integrated suite of spectroscopic, thermal, imaging, and mass spectrometric instruments delivers robust solutions for comprehensive microplastic analysis. These capabilities enhance our understanding of polymer pollution, particle dynamics, and chemical hazards, guiding mitigation strategies and regulatory efforts.

Reference

1. Kühn S., Jamieson A., Keighley R., Egelkraut-Holtus M. “In every ocean, at every depth - microfibers and microplastics.” Shimadzu News 2 (2018).
2. Nikolaou M., Neofitou N., Skordas K., et al. “Fish farming and anti-fouling paints: a potential source of Cu and Zn in farmed fish.” Aquaculture Environment Interactions 5 (2014): 163–171.
3. Yasojima M., Mizuka H., Mine T., et al. “Adsorption Characteristics of Chemical Substances on Microplastics.” JSWE 22nd Symposium (2019).