Verifying Raw Materials by Spatially Offset Raman Spectroscopy

Significance of the Topic

Ensuring the correct identity of incoming raw materials is critical in pharmaceutical and industrial production to prevent costly errors, contamination risks, and delays. Traditional Raman spectroscopy requires opening opaque or fluorescent packaging, increasing handling time and resource demands. Spatially offset Raman spectroscopy (SORS) offers a noninvasive approach to verify material identity through a variety of containers, streamlining quality control and improving workflow efficiency.

Objectives and Study Overview

This technical overview examines the implementation of SORS in the Agilent RapID Raman system for raw material identity (RMID) verification. It describes the underlying principles of SORS, the method for building and validating a reference library through original packaging, and the system’s performance in a production environment.

Methodology and Instrumentation

Methodology:

• SORS Principle: Acquire two Raman spectra at zero offset and at a spatial offset on the container surface.
• Scaled Subtraction: Subtract the scaled offset spectrum from the zero-offset spectrum to eliminate container contributions and isolate the contents spectrum.
• Library Training: Measure reference spectra through production packaging at multiple points, build a statistical model, and perform validation checks before release.
• Batch Analysis: Automate barcode scanning, acquire spectra in ~10 seconds each, and provide immediate pass/fail results.

Used Instrumentation:

• Agilent RapID Raman system with diode laser excitation
• Spatially offset collection optics
• CCD detector and spectrometer
• Integrated barcode scanner and software library module

Main Results and Discussion

SORS successfully recovered high‐quality Raman spectra of sucrose through a 1.5 mm thick polypropylene pot, matching reference spectra with minimal background interference. Conventional Raman through opaque packaging failed due to fluorescence and scattering. In a warehouse trial, 100 sacks were verified in under 30 minutes, demonstrating the method’s speed and scalability. The software generated real‐time batch reports and interfaced smoothly with LIMS for record keeping.

Benefits and Practical Applications

• Noninvasive verification reduces sample handling, contamination risk, and cleanup requirements.
• Rapid analysis (<10 s per sample) accelerates QC workflows and alleviates bottlenecks.
• Flexible library training accommodates diverse packaging materials (plastic, paper, glass).
• Seamless integration with LIMS and networked reporting supports traceability and compliance.

Future Trends and Opportunities

• Expanding the spectral library to include complex formulations and multi‐layer packaging.
• Incorporating machine learning algorithms for enhanced spectral deconvolution and identification confidence.
• Developing portable, automated SORS probes for in‐line process monitoring and remote field analysis.
• Integrating with other spectroscopic modalities (e.g., near‐infrared) for complementary information and broader applicability.

Conclusion

Spatially offset Raman spectroscopy integrated into the Agilent RapID system provides a robust, noninvasive solution for raw material identity verification through opaque packaging. Its rapid analysis, minimal sample preparation, and seamless data integration make it a powerful tool for quality control in pharmaceutical and industrial settings, with promising avenues for further technological advancement.

References

• Agilent Technologies. Technical Overview: Verifying Raw Materials by Spatially Offset Raman Spectroscopy. 2018.