ELECTRON-PARAMAGNETIC-RESONANCE (EPR) SPECTROSCOPIC ANALYSIS OF COPPER-BASED PRESERVATIVES IN PINUS-SYLVESTRIS

Electron paramagnetic resonance spectroscopy (EPR) was used to investi gate the forms of copper present in Pinus sylvestris treated with seve ral wood preservative formulations. Anisotropic Cu (II) signals, indic ative of immobile Cu2+ ions were found for all treated wood samples ir respective of formulation. Correlations of the electronic parameters A (II) and g(II) indicated that copper in the wood treated with amine co pper was complexed with 3 or 4 nitrogen atoms from the amine ligands. Formulations containing copper fixed using nitrite ions showed two cle arly different copper species in the treated wood. The major form, whi ch was resistant to leaching, had EPR spectral parameters suggesting a complex of the type CuN2O2. In nitrogen free formulations copper appe ared to be complexed to 4 oxygen atoms in a distorted octahedral envir onment. The copper-chromium containing formulations gave a broad Cr (I II) signal and a sharp characteristic signal indicating a small quanti ty of Cr (V) in the treated wood which was stable in wood under dry, l aboratory storage but which disappeared after leaching. Overall these studies have demonstrated that the paramagnetic properties of wood sam ples treated with several Cu (II) based timber preservatives can be re adily examined using EPR spectroscopy and indicate that a variety of c opper complexes can be formed in preservative treated wood.