Low-frequency Raman spectrophotometer with wide laser illumination on the sample: A tool for pharmaceutical...

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Materials Science

Background:

• Raman spectroscopy is crucial for analyzing molecular vibrations.
• Existing Raman setups can be limited by laser spot size and light throughput.
• Pharmaceutical analysis requires sensitive and versatile spectroscopic tools.

Purpose of the Study:

• To present a new optical configuration for a Raman spectrophotometer.
• To enable variable laser spot size (3–3000 μm) with high Raman photon throughput.
• To facilitate rapid spectral acquisition and analysis in the pharmaceutical industry.

Main Methods:

• Developed an optical configuration for Raman spectrophotometry without beam splitters.
• Varied laser spot size and measured Raman spectra across a wide frequency range (10–2000 cm⁻¹).
• Employed chemometric models and hyperspectral imaging for quantitative and qualitative analysis of active pharmaceutical ingredients (APIs).

Main Results:

• Achieved a wide range of laser spot sizes with maintained high photon throughput.
• Enabled short integration times for spectral acquisition.
• Demonstrated successful quantitative and qualitative analysis of API mixtures, including polymorphs and excipients.

Conclusions:

• The new optical configuration is highly versatile for pharmaceutical applications.
• The instrument is suitable for characterizing new drugs and quality control of raw materials and processes.
• Applicable for both normal Raman measurements and surface-enhanced Raman scattering (SERS).