Harald Pasch
Complex polymers are distributed in more than one way in terms of molecular heterogeneity. In addition to the molar mass distribution, they are frequently distributed with respect to chemical composition, functionality, and molecular architecture. 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 selective analytical techniques is assumed to yield two-dimensional information on the molecular heterogeneity.
The present article discusses the principles of combining different analytical techniques in multidimensional analysis schemes. The most promising protocols for coupled techniques are the combination of two different chromatographic methods and the combination of chromatography and spectroscopy. This article reviews the basic principles of two-dimensional chromatography combining interaction chromatography and size exclusion chromatography. In the use of liquid chromatography with selective detectors, the coupling of different chromatographic techniques with Fourier-transform infrared and nuclear magnetic resonance spectroscopies and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry is highlighted.