Liquid chromatography-Fourier-transform infrared spectrometry

Over the past years the coupling of liquid chromatography (LC) and Fourier- transform infrared spectrometry (FT-IR) has been pursued primarily to achie ve specific detection and/or identification of sample constituents. Two app roaches can be discerned in the combination of LC and FT-IR. The first and simpler approach is to use a flow cell through which the effluent from the LC column is passed while the IR spectra are continuously recorded. The sec ond approach involves elimination of the LC solvent prior to IR detection u sing an interface which evaporates the eluent and deposits the analytes ont o a substrate. This paper provides a general overview of flow-cell based IR detection and briefly discusses early solvent-elimination interfaces for L C-FT-IR. A more comprehensive description is given of interface systems whi ch use spraying to induce rapid eluent evaporation, and which basically rep resent the state-of-the-art in LC-FT-IR. Finally, the interface systems sui table for reversed-phase LC are summarized and the perspectives of LC-FT-IR are discussed. The overview indicates that flow-cell LC-FT-IR has rather p oor detection limits but can be useful for the specific and quantitative de tection of major constituents of mixtures. Solvent-elimination techniques, on the other hand, provide much better sensitivity and enhanced spectral qu ality which is essential when unambiguous identification of low-level const ituents is required. (C) 1999 Elsevier Science B.V. All rights reserved.