Improving verification with Orbital Raster Scan technology

Importance of the topic

Raman spectroscopy provides high chemical specificity but struggles to characterize heterogeneous samples due to its small interrogation area per measurement. Orbital Raster Scan (ORS) technology addresses this limitation by rapidly moving a tightly focused laser beam over a larger region, yielding spatially averaged spectra that better represent sample composition. This advance is especially critical for industries such as pharmaceuticals and quality control where heterogeneous formulations are common.

Objectives and study overview

This Application Note evaluates the performance of ORS in handheld Metrohm Instant Raman Analyzers (Mira P) when analyzing effervescent cold relief tablets. The study aims to compare conventional point sampling (ORS off) against ORS-enabled single scans, demonstrating improvements in spectral consistency, acquisition speed, and verification accuracy using statistical methods.

Methodology and instrumentation

Samples: Equate and Alka-Seltzer Plus effervescent cold tablets
Instrument: Mira P Advanced handheld Raman analyzer equipped with Orbital Raster Scan, 785 nm excitation, 5 mW laser power, SWD attachment, and MiraCal software for data collection and processing.
Experimental design:

• Collected 60 spectra on Equate tablets with ORS off, varying integration times (1–10 s).
• Generated an averaged ORS off spectrum and compared it to a single ORS on scan.
• Built a training set from Equate data to statistically verify Alka-Seltzer tablets using p-values.

Main results and discussion

ORS off measurements showed significant spectral variability when sampling different tablet areas. Averaging 60 off-axis spectra reduced noise but required extended acquisition time. A single ORS on scan produced a spatially averaged spectrum that closely matched the averaged ORS off result, demonstrating rapid and representative sampling.
Verification of Alka-Seltzer against the Equate training set using a p-value approach yielded a FAIL result (p=0.008), confirming that the two formulations differ despite similar spectral features.

Benefits and practical applications

ORS technology offers:

• Improved representativeness for heterogeneous samples in a single measurement.
• Reduced sampling time and user effort by eliminating multiple point analyses.
• Enhanced reliability of identity verification in pharmaceutical quality control and field analysis.

Future trends and opportunities

Integration of ORS with advanced chemometric models and machine learning is expected to further enhance detection sensitivity and discrimination of complex mixtures. Continuous improvements in portable Raman instrumentation may enable real-time in-field monitoring of formulation consistency and counterfeit detection.

Conclusion

Orbital Raster Scan technology in the Mira P Raman analyzer significantly improves sampling of heterogeneous materials by delivering high-resolution, spatially averaged spectra in a single scan. This innovation streamlines workflows in pharmaceutical verification and broader analytical chemistry applications.

Reference

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