Development of a New Characterization Method to Analyse Pyrethroid Compounds Penetration in Wood Material by Immunolabelling

摘要

The preservative efficacy of organic biocidal products is strongly related to their capacity of penetration and retention within wood tissues. The specific detection of the pyrethroid insecticide is currently obtained after extraction followed by chemical analysis by chromatography techniques. However visualizing the insecticide active substance within the wood structure requires specific probes together with microscopy techniques. Therefore, the aim of the present work was to apply a new methodology based on antibody-antigen recognition and electronic microscopy to visualize, directly, pyrethroids in wood products. A polyclonal antibody directed against cypermethrin was developed and implemented on Pinus sylvestris wood samples coated with technical cypermethrin. The antibody was tested on impregnated wood and the specific recognition of the insecticide was visualized in transmission electron microscopy (TEM). The immunogold-TEM assay revealed the synthetic active substance's capacity to penetrate inthe wood. The depth of penetration was measured on sections taken at increasing distances from the coated surface of the wood. Results correlated with chemical analyses carried out by gas chromatography with electron capture detector (GC-ECD) after extraction. In addition, the immuno-TEM investigation allowed visualizing, for the first time at the ultrastructure scale of resolution, that cypermethrin was able to diffuse within the secondary wood cell walls.