Solving Our Plastic Problem: Advances in Microplastics Analysis

Importance of the Topic

Modern society depends on plastics, whose durability leads to persistent pollution. Microplastics (1 µm–5 mm) and emerging nanoplastics (<1 µm) have been detected in water, soil, air, and living organisms. Standardized, reliable analytical methods are critical to assess environmental distribution, human exposure, and health risks.

Objectives and Study Overview

This whitepaper series examines advances in microplastics analysis, ranging from routine laboratory testing to regulatory requirements and best practices. Key goals include:

• Characterizing particle size, shape, number, mass, and polymer type.
• Comparing analytical techniques (LDIR, FTIR, Raman, GC-MS).
• Surveying standardization projects (ISO, CEN, ASTM).
• Demonstrating workflows for diverse matrices: water, sediment, biota, consumer products.

Methodology and Instrumentation

Microplastic isolation typically involves organic matter removal (e.g., Fenton’s reagent or enzymatic digestion), density separation or filtration, and transfer to analysis substrates. Instruments featured:

• 8700 LDIR Chemical Imaging System (Agilent): QCL-based IR imaging, on-filter analysis using gold-coated polycarbonate membranes, fully automated particle detection (10–500 µm), spectral matching via Clarity software.
• FTIR Microscopy: Single-point and focal plane array systems for spectral imaging; longer acquisition times, liquid-nitrogen cooling, high data volumes.
• Raman Microscopy: Sub-µm spatial resolution; fluorescence and sample damage can limit throughput.
• Pyr-GC-MS and TED-GC-MS: Provide total mass and polymer identity, destructive but rapid mass quantification without extensive sample prep.

Main Results and Discussion

On-filter LDIR analysis reduced sample prep by two steps and achieved 99% PET identification in bottled water and groundwater samples. Analysis time per particle was <10 s, with reliable detection down to 10 µm. Bottled water surveys showed an average of 13 microplastics per liter (mean size 77 µm), with imported brands exhibiting four-fold higher contamination than local. Groundwater bores adjacent to industrial activities revealed polymer profiles matching local sources (e.g., PVC near meat facilities, PE near nurseries).

Benefits and Practical Applications

Automated LDIR workflows offer:

• High throughput analyses with low hands-on time.
• Reduced contamination risk via on-filter measurement.
• Traceable QA/QC: cleanroom operation, blanks, recovery tests, ISO 17025 accreditation.
• Comprehensive reporting: particle count, size distribution, polymer type, mass estimates.

Future Trends and Applications

Ongoing developments include expanded spectral libraries (weathered polymers), machine-learning algorithms for rapid classification, integration of IR and thermal techniques for combined mass and number metrics, and sub-10 µm detection enhancements. Regulatory standards (ISO 24187, ISO 16094 series, ASTM D8332-20) will drive harmonization and routine monitoring in water, food, consumer products, and environmental matrices.

Conclusion

Advances in QCL-based LDIR imaging, combined with rigorous sample prep and QA/QC, enable fast, reliable microplastics analysis. Standardization efforts and improved instrumentation will support large-scale environmental studies and regulatory compliance.

References

Frias J.P.G.L.; Nash R. Mar. Pollut. Bull. 2019, 138, 145–147
ISO FDIS 24187; ISO 16094-1/2/3/4; ASTM D8332-20
Eurofins, JRC, EUROqCHARM, WEPAL-QUASIMEME proficiency tests