Microplastics Analysis Doesn’t Need to Be So Hard

Significance of the Topic

The widespread presence of microplastics in ecosystems and food chains has raised global concerns about environmental and human health impacts. Traditional methods for identification and quantification are time-consuming and labor intensive, driving the need for faster, more automated analytical solutions.

Objectives and Article Overview

This article reviews a novel infrared chemical imaging approach using quantum cascade laser (QCL) technology in the Agilent 8700 LDIR system. The goal is to simplify microplastics analysis by integrating rapid automated workflows that deliver reliable chemical identification, size measurement, and statistical reporting in real time.

Methodology

• Sample preparation mirrors conventional infrared protocols; particles are deposited onto reflective slides.
• The Agilent 8700 LDIR employs a tunable QCL mid-infrared laser that focuses high power onto individual particles, yielding strong absorption signals in under one second per spectrum.
• The system automatically scans a selected area to locate particles, measures their dimensions, and compares each spectrum against an embedded infrared library for immediate identification.
• Targeted wavelength imaging enables rapid screening of specific polymers (e.g., polystyrene at 1490–1508 cm⁻¹) in minutes for large sample areas.

Instrumentation

• Agilent 8700 Laser Direct Infrared (LDIR) Imaging System
• Quantum Cascade Laser (QCL) Mid-Infrared Source
• Infrared Reflective Slides

Key Findings and Discussion

• Detection of 39 particles in a 3×3 mm area completed in five minutes (≈8 seconds per particle) including real-time analysis.
• Analysis of sewage sludge identified 1028 microplastics in a 5×5 mm region at approximately eight seconds per particle, with automatic mapping and color-coded classification.
• Comparative study with FTIR imaging: conventional mosaic-based FTIR required 11 hours to generate 4.2 million spectra for 871 particles, whereas LDIR reduced total analysis time to around two hours.
• Targeted QCL screening for specific polymers achieved a 5×5 mm survey in two minutes, minimizing data volume and sample handling.

Benefits and Practical Applications

• Significant reduction in analysis time without sacrificing spectral fidelity.
• Automated identification and quantitation with embedded library matching and statistical reporting.
• Minimal user intervention and simplified load-and-go operation suitable for non-experts.
• Targeted data acquisition optimizes throughput and resource utilization.

Future Trends and Applications

• Standardization of LDIR workflows for regulatory and environmental monitoring programs.
• Enhanced imaging resolution and sensitivity for detecting smaller microplastics fractions.
• Integration with complementary techniques such as Raman spectroscopy and mass spectrometry for comprehensive polymer characterization.
• Development of portable or field-deployable LDIR units for on-site analysis and rapid decision-making.

Conclusion

The Agilent 8700 LDIR system represents a breakthrough in microplastics analysis, offering a streamlined, high-throughput approach that delivers rapid, reliable chemical identification and statistical reporting. Its automated, targeted measurement strategy dramatically reduces time and effort compared to traditional FTIR, paving the way for broader adoption in environmental research and quality control laboratories.

References

Agilent Technologies Inc., White Paper 5994-1584EN, December 2019