Molecular Spectroscopy

Both identify molecular vibrations and functional groups, but through different physical mechanisms and with different strengths. FTIR measures infrared absorption and is highly sensitive to polar bonds (C=O, O-H, N-H); Raman measures inelastic light scattering and excels at non-polar bonds, symmetric vibrations and samples in water (where FTIR struggles), and requires no direct contact with the sample.

UV-Vis measures electronic absorption, used to determine compound concentration (via Beer-Lambert law), assess purity, and characterize chromophores — conjugated systems, aromatic rings and other light-absorbing molecular features.

CD measures the differential absorption of left- and right-circularly polarized light, which is sensitive to molecular chirality. For proteins, it estimates secondary structure content (alpha-helix, beta-sheet, random coil) and can detect conformational changes or unfolding — information not available from FTIR or UV-Vis alone.

Fluorescence spectroscopy is used when the analyte itself is fluorescent or can be labeled with a fluorescent probe, offering much higher sensitivity than absorption-based techniques. It is applied to detect trace fluorescent compounds and to study molecular interactions such as binding events, through changes in fluorescence intensity or wavelength.

Percevia is a Brazilian analytical laboratory based in São Paulo, offering UV-Vis, FTIR, Raman, circular dichroism and fluorescence spectroscopy as outsourced analytical services for pharmaceutical, cosmetics and materials companies.