Abstract:
The bioassay with Aspergillus niger is a simple way of determining the presence and amount of pentachlorophenol or tributyltin oxide in wood, but it does not appear useful for measuring strongly fixed chemicals such as chromated copper arsenate, borate, and fluoride. Its effectiveness in detecting other preservatives has not been reported. Accordingly, the bioassay was evaluated for its ability to detect various concentrations of 15 preservatives introduced into blocks of ponderosa pine. These results were compared with those from modified soil-block tests involving the same chemicals. Several of the formulations-three quaternary ammonium compounds, copper naphthenate, and Folpet imparted some decay resistance to the blocks but were not detectable with the bioassay. The remaining chemicals were all detectable, although sensitivities varied. These results suggest that the Aspergillus bioassay can be useful for detecting many wood preservatives.
