Performance Attributes of the Agilent 8700 Laser Direct Infrared (LDIR) Chemical Imaging System

Significance of the Topic

The rapid rise in microplastic pollution across aquatic, terrestrial, and atmospheric environments demands reliable, high-throughput analytical methods capable of determining chemical identity, size, shape, and mass of individual particles. Conventional FTIR and Raman imaging systems face limitations in speed, signal-to-noise ratio, and workflow complexity, hindering large-scale environmental monitoring. The Agilent 8700 Laser Direct Infrared (LDIR) Chemical Imaging System introduces a quantum cascade laser-based approach designed to overcome these challenges through full automation and accelerated analysis times.

Objectives and Study Overview

This study outlines the automated particle analysis workflow of the Agilent 8700 LDIR system for microplastics characterization and evaluates its performance metrics, including particle size accuracy and precision, size-ranging precision, and particle count repeatability. A direct comparison with a third-party digital microscope (Leica DVM6) validates the measurement reliability.

Used Instrumentation

• Agilent 8700 LDIR Chemical Imaging System with quantum cascade laser source and Agilent Clarity software
• Digital Microscope Leica DVM6 for validation measurements
• Infrared-reflective glass slides (MirrIR, Kevley Technologies)

Methodology

Clear polyethylene microspheres (0.96 g/cc, 38–45 µm) were dispersed in ethanol and deposited onto IR-reflective slides under laminar flow. The Agilent Clarity software’s automated workflow was configured to collect visible and infrared images, perform library-based spectral identification, and measure particle diameters. Particle size accuracy and precision were assessed via three repeated analyses on the same sample area, while size-ranging precision and particle count repeatability were determined by six consecutive scans of a mixed microplastic sample spanning 20 to 5 000 µm.

Main Results and Discussion

• Particle size measurements for beads A3 through A9 fell within certified 38–45 µm ranges, with standard deviations between 0.02 and 0.43 µm. Slight overestimation was observed for A2 (average 47.04 µm).
• Validation with the Leica DVM6 confirmed close agreement (within 1 µm) across all tested particles.
• Size-ranging precision across buckets (0–30, 30–50, 50–100, 100–200 µm) showed standard deviations of 10, 7, 3, and 2 particles, respectively; larger size classes exhibited zero deviation.
• Total particle count repeatability over six scans averaged 871 particles with a standard deviation of 18 (RSD ~2.1%).

Benefits and Practical Applications

The Agilent 8700 LDIR system offers:

• Fully automated chemical imaging and analysis workflow requiring minimal user intervention
• High throughput with analysis times in minutes rather than hours
• Flexible field of view adjustments (1–40 µm pixel size, micron to centimeter scale areas)
• Integrated visible imaging for particle morphology and classification
• Rapid identification using commercial or custom spectral libraries
• Relative quantitation without complex method development
• Applicability to environmental microplastics monitoring, drinking water QA/QC, and pharmaceutical surface characterization

Future Trends and Potential Applications

Emerging directions include integration of machine-learning algorithms for automated polymer classification, expansion of spectral libraries for novel plastic types, development of field-portable QCL-based imagers, and standardization of LDIR-based protocols for regulatory monitoring. Combining LDIR with complementary techniques (e.g., Raman or mass spectrometry) may further enhance particle characterization depth and throughput.

Conclusion

The Agilent 8700 LDIR Chemical Imaging System demonstrates exceptional accuracy, precision, and repeatability for microplastic particle sizing and counting. Its fully automated workflow and rapid analysis capabilities position it as a leading solution for reliable environmental and quality-control applications.

References

• Agilent Technologies, Inc. Performance Attributes of the Agilent 8700 Laser Direct Infrared (LDIR) Chemical Imaging System for Microplastics Characterization. White Paper 5994-4619EN, August 31, 2022.