Quantification of LCC linkages

As it has been shown above, the quantification of LCC linkages with traditional wet chemistry methods is limited mostly to relative quantification of carbohydrate sites linked to lignin [18,67-74]. 

LCC linkages present in very low concentrations. Therefore, in spite of successful NMR analysis of major lignin and some carbohydrate moieties [43,82], the quantification of LCC linkages in these preparations would be much more difficult than in specific preparations enriched with LCC linkages. 

As it has been shown earlier, the quantification of LCC linkages with traditional wet chemistry methods is limited mostly to relative quantification of carbohydrate sites linked to lignin. In contrast, our quantitative 2D NMR approach [21] allows for quantification of lignin sites involved in LCC linkages of different types. However, it does not provide information on the specific carbohydrate linkage sites yet. Therefore, a combination of quantitative NMR analysis and appropriate wet chemistry methods, such as a routine carbohydrate analysis, along with the methylation and DDQ oxidation degradation techniques, could be the best approach for comprehensive LCC analysis. 

Signals of LCC benzyl ether of the C2 type are overlapped with a signal of the spirodienone structure (E, Fig. 1). The latter can be quantified from another individual signal and the amount of C2-type LCC linkages can be determined then by the difference [21]. However, considering the relatively low amounts of these structures, this type of quantification should be considered semiquantitative. 

---