Solid-phase fluorescence: Reproducibility and comparison with the solution states.

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Materials Science

Background:

• Solid-phase fluorescence excitation-emission matrix (SPF-EEM) spectroscopy offers non-destructive analysis of solids.
• Lack of standardized methods hinders interdisciplinary sample comparison.
• 3D printing presents an opportunity for developing standardized measurement tools.

Purpose of the Study:

• To design and evaluate a 3D-printed cell for reproducible SPF-EEM measurements of powders.
• To assess the performance of the cell across various fluorescent materials.
• To compare solid-state fluorescence spectra with solution-state spectra.

Main Methods:

• Development of a custom 3D-printed cell for solid-state fluorescence measurements.
• Application of the cell to a range of fluorescent powders including proteins, amino acids, and chemicals.
• Repetitive measurements (n=3) to assess reproducibility of fluorescence peak wavelength and intensity.
• Comparison of solid-state spectra with solution-state spectra.

Main Results:

• The 3D-printed cell demonstrated high reproducibility in fluorescence measurements.
• Solid proteins showed unique broad peaks not observed in solution, attributed to amino acid residues.
• Inner-filter effects potentially caused fluorescence loss in powdered rhodamine B and fluorescein sodium salt.
• Differences in solid-state fluorescence were observed for some non-colored molecules, linked to environmental interactions.

Conclusions:

• The 3D-printed cell provides a reproducible method for SPF-EEM analysis of powders.
• Solid-state fluorescence can reveal unique spectral features influenced by molecular environment and structure.
• Standardized SPF-EEM measurements are crucial for reliable analysis and comparison across different studies.