Comparative investigations between thermal and microwave assisted digestion as a novel tool for the chemical analysis of inorganic wood preservative components
H Ahl, J Fromm, E Melcher
The correct chemical impregnation of wood requires an internal as well as external quality control of the treated wood. The active is located in a solid matrix, therefore it is often difficult to analyse such material since most analytical procedures are based on liquid systems. Because of this quite a number of methods – like extraction or thermal digestion - were developed in order to transfer the active to a suitable solvent, some of which are standardised. However, due to technical progress, continuously new analytical equipment is developed. This raises the question: How does this new tool practically compare to well established procedures? In order to introduce the method ‘microwave assisted digestion’ first systematic research was carried out, in which laboratory impregnated samples as well as samples from commercial practice were used. These results were compared with data obtained by means of a thermal digestion standard procedure (DIN 52161-7). In addition of these results a short economic overview comparing the costs of both techniques will be provided.
Keywords: wood preservative, copper, chromium, digestion, chemical analysis