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Rejection of Fluorescence Background in Resonance and Spontaneous Raman Microspectroscopy
Published on: May 18, 2011
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Fluorescence-suppressed time-resolved Raman spectroscopy of pharmaceuticals using complementary metal-oxide
Tatu Rojalin1,2, Lauri Kurki3, Timo Laaksonen4
1Division of Pharmaceutical Biosciences, Centre for Drug Research, University of Helsinki, P.O. Box 56, 00014, Helsinki, Finland. tatu.rojalin@helsinki.fi.
Analytical and Bioanalytical Chemistry
|November 10, 2015
Summary
This study introduces a new time-resolved Raman spectroscopy technique using a picosecond pulsed laser and a specialized detector. This method effectively suppresses fluorescence, revealing hidden drug features for enhanced chemical analysis.
Area of Science:
- Spectroscopy
- Analytical Chemistry
- Materials Science
Background:
- Traditional Raman spectroscopy struggles with strong fluorescence interference.
- Weak Raman signals are often obscured by background fluorescence.
- High photon energy excitation can enhance Raman signal strength.
Purpose of the Study:
- To develop and demonstrate a time-resolved Raman spectroscopy technique.
- To overcome fluorescence background in drug analysis.
- To reveal previously unseen Raman features.
Main Methods:
- Utilized a 532-nm picosecond pulsed laser.
- Employed a time-gated complementary metal-oxide semiconductor (CMOS) single-photon avalanche diode (SPAD) detector.
- Acquired time-resolved Raman spectra of various drug compounds.
Main Results:
- Successfully suppressed fluorescence background, enabling clearer Raman spectra.
- Observed previously unseen Raman features in drugs like caffeine, ranitidine hydrochloride, and indomethacin.
- Demonstrated direct compound identification from raw data without processing.
- Validated results with Density Functional Theory (DFT) calculations for ranitidine hydrochloride.
Conclusions:
- The time-resolved Raman spectroscopy technique offers significant advantages over traditional methods.
- This approach enables enhanced analysis of drugs, including amorphous and crystalline forms.
- The technology shows promise for pharmaceutical analysis, process analytical technology (PAT), and life sciences.
