*2.3. Copper Leaching*

Further studies were conducted to assess the impact of the peroxide treatment on the leachability of copper from the treated wood. Thirty samples of red pine (*Pinus resinosa*) sapwood were cut to the dimensions of 50 mm long × 15 mm radial × 25 mm tangential wood fiber direction and were conditioned to constant mass at 20 ◦C and 65% relative humidity (RH). Twenty samples were pressure treated with an aqueous suspension of MBCC to an average gauge retention of 3.2 kg of MBCC per cubic meter of wood. Specimens were reconditioned to constant weight at 20 ◦C and 65% RH following treatment. Ten specimens were dip treated in a 20% solution of hydrogen peroxide (pH 6) and ten were dip treated in water for five minutes. The wood specimens were then reconditioned to constant weight and evaluated for copper leaching using the immersion cycle specified in section 7.3 of the OECD Guidance document [19]. The mass of the samples was recorded, and the samples were completely immersed in water for 120 min, removed from the water and allowed to drain for 10 s, allowing run-o ff to return to the water. The leachate samples were collected and stored in the freezer. The test specimens were weighed again and then left to dry at laboratory temperature until the next immersion day. Immersion occurred on days: 1, 3, 7, 9, 11, 14, 16 and 22. Leachate samples were then sent to Maxxam Analytics (Burnaby, BC, Canada) for copper analysis by Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES). After all immersion cycles had been completed the samples were left to dry at laboratory temperature. Once dry the leached samples were milled to pass through a 40-mesh screen and pressed into pellets. The pellets were measured for total copper using an ARL ™ QUANT'X EDXRF Spectrometer (ThermoFisher Scientific, Waltham, MA, USA) [20].
