Taro Uchida, Seiichiro Higuchi
A simplified diffuse reflectance infrared Fourier transform (DRIFT) system using commercial silver powder was investigated as an alternative to previously reported silver colloid/filter-paper systems for infrared signal enhancement. Isonicotinamide, nicotinamide, and nicotinic acid were employed as model compounds to evaluate the spectral behaviour obtained using this simplified DRIFT system. Significant band-dependent enhancement was observed for isonicotinamide and nicotinamide when the samples were subjected to solvent-assisted mixing with silver powder followed by drying. In contrast, simple dry mixing with silver powder produced little or no enhancement, and the control compound nicotinic acid showed no comparable spectral changes. The enhanced spectra exhibited non-uniform increases in band intensity together with peak shifts, band splitting, and changes in spectral shape, suggesting that the observed spectral changes cannot be explained by simple physical mixing with silver powder. The simplified powder DRIFT system enabled observation over a broad spectral region without support-derived absorption and revealed band-dependent infrared enhancement together with peak shifts, band splitting, and spectral shape changes.