A unified approach to the chromatography/FT-IR interface

Most previous interfaces between a Chromatograph and an FT-IR spectrometer have been applicable to only one type of chromatograph-gas, liquid, or supercritical fluid. In this paper, the similarities and differences between various chromatography/FT-IR interfaces are described, and an interface which should be equally applicable to all three types of chromatography is proposed. In each case, the mobile phase is eliminated while the eluting components are condensed in a small area on a moving substrate. The spectra are then measured using an FT-IR microscope. The methods by which the mobile phase is eliminated depend on the nature of the chromatography, while the infrared sampling technique is determined by the nature of the substrate. The relative merits of transmission, reflection-absorption, diffuse reflection, and diffuse transmission spectrometry are discussed.