TREATED WOOD ANALYSIS

The analysis of treated wood samples for active retention allows Zelam to provide customers better support and quality assurance.

The analysis starts with cutting the solid sample into smaller squares and milling the timber to a constancy similar to saw dust. This allows the solvent to leach into the timber sample the solvent used depends on the type of active that is to be extracted.

A sample of the milled timber is weighed and a solvent is added to the sample. To help the process along the solvent is heated in a process called refluxing (Fig 1).

The process also extracts large amounts of resin and other compounds which may interfere with the analysis. The next step is the ‘clean up’ process which uses a sodium hydroxide wash to help remove the unwanted compounds.

The sodium hydroxide changes the pH of the extraction solution which pushes the unwanted resins into the lower water phase, but the active chemical stays in the solvent phase (fig 2).

The final step is to dry the solvent to remove any traces of water and then filter the sample to remove any solid material.

The sample is then ready to be analyzed using either Gas Chromatography or Liquid Chromatography.