Coupled Liquid Chromatographic Techniques in Molecular Characterization
Polymers and Rubbers
Published Online: 15 SEP 2006
Copyright © 2000 John Wiley & Sons, Ltd. All rights reserved.
Encyclopedia of Analytical Chemistry
How to Cite
Kilz, P. and Pasch, H. 2006. Coupled Liquid Chromatographic Techniques in Molecular Characterization. Encyclopedia of Analytical Chemistry. .
- Published Online: 15 SEP 2006
Complex polymers are distributed in more than one direction of molecular heterogeneity. In addition to the molar mass distribution (MMD), they are frequently distributed with respect to chemical composition, functionality, and molecular architecture (see Size-exclusion Chromatography of Polymers). For the characterization of the different types of molecular heterogeneity it is necessary to use a wide range of analytical techniques. Preferably, these techniques should be selective towards a specific type of heterogeneity. The combination of two or more selective analytical techniques is assumed to yield multidimensional information on the molecular heterogeneity.
The present review presents the fundamental ideas of combining liquid chromatography (LC) with other analytical techniques in multidimensional analysis schemes (see Size-exclusion Chromatography of Polymers; Gas Chromatography in Analysis of Polymers and Rubbers; Field Flow Fractionation in Analysis of Polymers and Rubbers). The capabilities and limitations of different coupling techniques are discussed and a number of relevant applications are given. It is shown that multidimensional structural information can be obtained when different chromatographic techniques are combined. Another approach is the hyphenation of LC with information-rich detectors. These detectors include molar mass-sensitive detection systems, such as on-line viscometry (VISC) and light scattering (LS). Information on the chemical composition of complex polymers can be obtained when spectroscopic techniques, like Fourier transform infrared (FTIR) (see Infrared Spectroscopy in Analysis of Polymer Structure–Property Relationships), nuclear magnetic resonance (NMR) or mass spectrometry (MS) are coupled to LC.
The basics and applications of multidimensional LC are addressed rather extensively. A brief introduction to different separation mechanisms is given and the particular requirements for the first and second dimensions are discussed. In conclusion, state-of-the-art examples for on-line coupled two-dimensional (2-D) chromatography are demonstrated, and future developments are reviewed.