New detection strategies in chromatography hyphenated systems : LC/ NMR, LC/FTIR and GC/FTIR

This report describes the on-line hyphenation of LC with IR and NMR, and of GC with IR. The main problems in LC/IR systems are the IR absorption of most commonly used LC mobile phases, and the relatively low sensitivity of the IR spectrometer in comparison to other LC detectors. Problems arise especially for reverse phase separations because of the strong IR absorptions of water, methanol and acetonitrile. However, through ingenious interfaces it is nowadays possible to detect 10 ng quantities. Contrary to LC/IR, on- line GC/IR is already at an advanced state of development. This is mainly due to the fact that mobile phases used in GC do not exhibit IR activity. Recently double-hyphenated GC/IR/MS systems have become commercially available, using a low-cost mass spectrometer such as the MSD from Hewlett Packard or the ITD from Finnigan. These systems have already proven their identification power, and must be regarded as the best analytical tool for identification of onkwown analytes.