FT-IR Microscopic Analysis of Micro-particles

Importance of the Topic

Micro-particles are ubiquitous in pharmaceutical, electronic, environmental and industrial contexts. Their small size and complex composition often prevent bulk analysis and require methods capable of high spatial resolution. FT-IR microscopy offers non-destructive identification of individual particles, enabling rapid contamination screening, quality control and formulation studies.

Study Objectives and Overview

This application note (AN M105) illustrates how the LUMOS II II FT-IR microscope can reliably characterize micro-particles. Two practical examples are presented: the analysis of particulate contaminants filtered from a pharmaceutical formulation and the mapping of a defect inclusion within a multilayer acrylic varnish.

Methodology

Particles isolated on substrates are examined using automated ATR, transmission and reflection measurements. A motorized stage and knife-edge aperture provide adjustable sampling areas down to 10×10 µm. For mapping, a user-defined grid acquires spectra at each position. The OPUS Video-wizard guides users through background correction, data acquisition and spectral analysis. Library search tools facilitate rapid compound identification.

Used Instrumentation

• LUMOS II II FT-IR microscope with integrated Bruker spectrometer
• Motorized ATR crystal for fully automated background and sample measurement
• 8× objective supporting ATR, transmission and reflection modes
• Knife-edge apertures adjustable to micro-scale dimensions
• Motorized stage for point measurements and area mappings
• OPUS software with video-wizard interface and built-in library search

Main Results and Discussion

In the pharmaceutical example, particles filtered through a 5 µm gold membrane were measured at three locations. Library matching identified cellulose, talcum and a minor polymeric component exhibiting amide bands. This multi-component analysis revealed that visual uniformity can mask mixed contaminants. In the second case, a 22 µm inclusion within acrylic varnish was mapped on a 7×7 grid (12×12 µm apertures). Chemical imaging based on characteristic amide bands delivered high-contrast visualization, and the central spectrum was assigned to polyamide via library search.

Benefits and Practical Applications

• Non-destructive, single-particle chemical identification
• High lateral resolution for complex multi-component samples
• Fully automated ATR and mapping routines reduce operator error
• Integrated spectral library search accelerates unknown identification
• Versatile for contamination analysis, material coatings, environmental particulates and product quality control

Future Trends and Opportunities

Advancements may include hyperspectral chemical imaging, integration with machine learning for automated pattern recognition, expanded spectral databases for broad compound coverage, cryo-ATR techniques for temperature-sensitive samples and field-deployable FT-IR microscopy systems for on-site analysis. These developments will further enhance throughput, accuracy and applicability across industries.

Conclusion

The LUMOS II II FT-IR microscope demonstrates exceptional capability for micro-particle characterization through automated, high-resolution ATR and mapping techniques. Its non-destructive workflow, combined with intuitive software and spectral library matching, makes it a powerful tool for routine laboratory analysis and research applications.