The remaining concentration of inorganic wood preservative components in EN 252 stakes after ground contact
E Melcher, H-W Wegen
In order to determine the biological efficiency and the remaining concentration of different inorganic and organic active ingredients during service, EN 252 specimens were impregnated with 3 copper based wood preservatives. The stakes were installed in the test field of the DESOWAG GmbH, Rheinberg, for at least 7 years. At the end of the field test some of these stakes were divided into 10 uniform segments. Afterwards each segment was milled and mixed to guarantee a nearly homogenous sample. After further sample preparation like an acidic digestion the remaining concentration of the inorganic components copper, zinc, boron and fluoride were measured by means of AAS, ICP and an ion selective electrode. Concerning the remaining concentration the following ranking of the investigated active ingredients could be deduced: Cr (90%)> Zn (60%)> Cu (40-70%) >= F (40%) > B (concentration <10%). Furthermore the results show that the remaining content of copper differs depending on the wood preservative used. The lowest content was detected for the CCZnF-formulation, the highest for the copper-quat-preservative. Furthermore it is obvious that the rate of biological decay correspond well with the distribution of the wood preservative components in the segments.
Keywords: INORGANIC ACTIVE INGREDIENT; ORGANIC ACTIVE INGREDIENT; WOOD PRESERVATIVE; CHEMICAL ANALYSIS; EN 252; FIELD TEST