Tributyltin napthenate (TBTN) is being substituted for tributyltin oxide (TBTO) in LOSP preservative formulations because its lower reactivity/better stability allows co-formulation with synthetic pyrethroids. Better stability may reduce molecular degradation both in-service and during analysis. It was considered necessary to check whether TBTO analysis methods were suitable for use on TBTN treated wood. Five analytical methods for TBTO in wood were applied to TBTN-treated pine sapwood, and evaluated for recovery, accuracy and precision. It was found that treated wood could be oven-dried before analysis, eliminating the need to run parallel moisture content determinations. The best performing method involved extraction of TBTN from oven-dry treated wood with acidified ethanol followed by AAS determination of tin. Performance was checked on freshly-treated and aged material.

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