Liquid phenol formaldehyde (PF) glue mixes used for plywood manufacture are strongly alkaline. At this pH insecticidal additives may not be stable for long periods. In order to establish practical working life of the synthetic pyrethroid insecticide, bifenthrin, in liquid PF glues the concentration of bifenthrin in the glue mix was measured under laboratory conditions over a 24 hour period. Glue batches were prepared in a laboratory mixer set up on an electronic balance with two dose rates of bifenthrin. The glue was stirred continuously, with a cover in place to reduce evaporation. Four replicate portions of glue were removed from the mixer and applied to fluoropolymer-coated rubber discs at fixed periods. The discs were cured immediately in an oven, during which time the film set and became detached from the surface. These discs were extracted with toluene-formic acid (90:10) mixture and the extracts analysed using capillary column GC with electron capture detection. Bifenthrin was found to be exceptionally stable in alkaline PF glue. When the glue was mixed under conditions preventing premature polymerisation, no measurable bifenthrin degradation occurred during the 24 hours.

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