Coupling of high-performance liquid chromatography to fourier transform infrared spectrometry using a heated gas flow modified thermospray

A thermospray was modified and used to couple high-performance liquid chromatography (HPLC) to Fourier-transform infrared (FTIR) spectrometry, which was applicable to both normal- and reversed-phase HPLC. Column effluents from the HPLC system were desolvated by thermospray and solutes were deposited as individual spots on a moving stainless-steel belt (0.025 mm thickness x 13 mm width) substrate, which continuously transferred the analytes into the diffuse reflectance (DRIFT) accessory of the FTIR, enabling identification of deposited solutes by measurement of the IR spectrum. The thermospray temperature and thermospray height were shown to influence the deposition of solutes. By use of a heated external nitrogen gas flow, desolvation of the reversed-phase HPLC eluents was improved and reduction of power supply in the thermospray capillary was achieved. Thus lower thermospray capillary temperatures could be used. The IR spectra of the separated individual components showed good agreement of the spectral features to those of standard FTIR spectra and no thermal degradation was found to occur.