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Four methyl cellulose samples in the degree of substitution range from 0.5 to 2.0 were characterised by combination of different analytical methods. Samples were analysed regarding their partial degree of substitution by hydrolysis and anion exchange chromatography with pulsed amperometric detection. For calibration of the chromatographic system, standard substances were isolated by preparative HPLC and their structure was confirmed by 13 C-NMR spectroscopy. For two methyl cellulose samples per-acetylation and 13 C-NMR with inverse gated decoupling was carried out for comparison with the chromatographic analysis. Endoglucanase fragmentation of methyl celluloses was performed and watersoluble and insoluble fractions were analysed separately. A preparative size exclusion chromatography system for enzymatic-degraded water-soluble methyl cellulose was developed and the molar masses of the individual fractions were examined by analytical size exclusion chromatography. By combination of endoglucanase fragmentation, preparative chromatography, hydrolysis and anion exchange chromatography an approach for the analysis of the substitutent distribution along the polymeric chain of water-soluble methyl cellulose could be established.

Since cross-linked hydrogels from oxyethylated lignins (OELs) are progressively more regarded as water-retaining soil improvements based on sustainable and biorenewable resources, an effort is made here to gain some insight into the biodegradation behavior of these materials. For this purpose, model soils with defined sand/lignin and sand/OEL ratios were incubated in a closed system under laboratory conditions, and carbon dioxide evolved by microbial lignin and OEL decomposition was determined. OELs with different oxyethylation/cross-linking degrees and water absorption capacities were included into the experiments and compared with respective types of parent technical soft wood and hard wood lignins. The results suggest a medium-to long-term biodegradability of OELs ensuring a long-term functionality of the hydrogel materials on the one hand and a subsequent integration of respective degradation products into the natural carbon cycles on the other hand. It was found that the short-term carbon mineralization rates of OELs are markedly lower compared to that of parent lignins and strongly dependent on (1) lignin type, (2) cross-linking/oxyethylation degrees of OEL, (3) corresponding swelling properties, and (4) OEL concentrations in model soils.

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