New Developments in the Analysis of Partially Acetylated Chitosan Polymers and Oligomers

A detailed structural analysis of partially acetylated chitosans is a prerequisite for the establishment of molecular structure-function relationships and also for the development of reliable applications for chitosan-based products. Today's second-generation chitosans are well-defined in terms of their degree of polymerisation (DP) and fraction of acetylation (F A), but less well in terms of their dispersity in DP (D DP), and typically not at all regarding their dispersity in F A (D FA). Moreover, all chitosans of today have a more or less random pattern of acetylation (P A), but enzymatic modification may yield chitosans with nonrandom P A. Novel methods based on capillary electrophoresis (CE) for D FA and enzymatic / mass spectrometric (MS) fingerprinting for P A are currently being developed, possibly paving the way for third-generation chitosans which will be even better defined and less disperse. In this chapter, we will briefly present the established gold standards for the analysis of DP, F A and D DP, and describe in more detail the emerging techniques for D FA and P A analysis of chitosan polymers. We will also briefly present the established methods, and describe in more detail the newly emerging mass spectrometric tools for the structural analysis of partially acetylated chitosan oligomers (paCOS). Quantitative MS sequencing allows the full structural description of paCOS mixtures, and it is also a prerequisite for enzymatic / MS fingerprinting analyses of chitosan polymers.