Analysis of Minute Objects Using the SurveyIR Sample Compartment Type Infrared Microscopy System

Importance of the Topic

The ability to analyze microscopic samples with high sensitivity and spatial resolution is essential for quality control, environmental monitoring, forensic investigations and materials research. Compact Fourier transform infrared (FTIR) systems that accommodate infrared microscopy accessories enable routine laboratory benches to perform detailed chemical analyses of particles, fibers and residues without requiring specialized, large-scale instruments or cryogenic cooling.

Study Objectives and Overview

This application note demonstrates the integration of Shimadzu’s IRSpirit™-X FTIR spectrophotometer with the SurveyIR sample-compartment infrared microscope to analyze minute objects down to approximately 60 μm. Key goals include:

• Evaluating transmission and ATR measurement modes for colorless particles, contaminant fibers and adhesives.
• Testing sample positioning and aperture selection for accurate centering and imaging.
• Comparing library search results using a standard library and a proprietary contaminant library.

Methodology and Instrumentation

The compact IRSpirit-X measures 390 × 250 × 210 mm and accepts SurveyIR in either landscape or portrait orientation. Two detector options are available: the temperature-controlled DLATGS model (TX/ZX series) and the LiTaO₃ model (LX series). The SurveyIR enables transmission, reflectance and ATR modes with six aperture sizes (60–2 000 μm), manual X-Y stage movement and real-time imaging.

Measurement parameters (Table 1) for transmission and ATR experiments:

• Resolution: 8 cm⁻¹
• Scans: 128
• Apodization: Square-triangle
• Detector: DLATGS

Key Results and Discussion

1. Colorless Minute Objects (Transmission):
• Tiny particles (~200 × 100 μm) were compressed on a diamond cell and measured through a φ160 μm aperture. Spectral matching against the Shimadzu Standard Library identified a mixture of sucrose and vegetable oil.

2. Contaminant Fibers (Transmission):
• Fibers (~100 μm wide, fibrous length) analyzed via transmission with φ160 μm aperture produced spectra matched to polyester and cotton in the Standard Library. Using Shimadzu’s contaminant library improved identification of mixed polyester/cellulose fibers.

3. Thick or Dark Samples (ATR):
• A sample (~600 × 400 μm) unsuitable for transmission was measured by single-reflection diamond ATR with the maximum 2 000 μm aperture. Results matched acrylic adhesives. For highly absorbing samples, a Ge crystal ATR is recommended to minimize spectral distortion.

The Z-axis fine-focus observation feature facilitated precise sample centering and dimension measurement. Switching between transmittance, reflectance and ATR modes was rapid and reproducible.

Benefits and Practical Applications

• Compact footprint allows installation on standard lab benches without liquid-nitrogen cooling.
• High signal-to-noise ratio and spectral resolution deliver reliable identification of micro-samples.
• Flexible measurement modes and aperture sizes support analysis of powders, fibers, residues and adhesives.
• Proprietary contaminant library enhances accuracy for complex mixtures encountered in environmental and food safety testing.
• Real-time imaging ensures accurate centering and documentation of measurement points.

Future Trends and Opportunities

As microspectroscopy evolves, future directions include integration of hyperspectral imaging, AI-driven spectral interpretation and automated particle screening workflows. Advancements in detector technology—such as cooled T2SL focal plane arrays—will broaden the dynamic range and speed of mapping applications. Expanding specialized spectral libraries for pharmaceuticals, microplastics and nanomaterials will further enhance identification capabilities in regulatory, forensic and research settings.

Conclusion

The combination of the IRSpirit-X FTIR and SurveyIR sample-compartment microscope offers a versatile, high-performance platform for analyzing minute objects in transmission and ATR modes. Its compact design, broad accessory compatibility and advanced library search tools enable precise chemical identification of particles, fibers and adhesives without the need for cryogenic cooling. This system is well suited for routine QA/QC, environmental monitoring and forensic laboratories.

Reference

Shimadzu Corporation. Fourier Transform Infrared Spectrophotometer IRSpirit-X Application Note: Analysis of Minute Objects Using the SurveyIR Sample Compartment Type Infrared Microscopy System. First Edition Dec. 2023. 01-00654-EN.