The HPLC method has been widely applied to quantitative determination of cyproconazole in preservative solutions. However, HPLC assay has not been successfully employed to determine cyproconazole content in treated wood. Some extractives from treated wood hinder cyproconazole determination because they have a similar retention time to that of cyproconazole on an HPLC chromatogram. In addition, large peaks of wood extractives appearing at early retention time also affect the determination of cyproconazole. In this paper, the application of solid-phase extraction to remove wood extractives that interfere with cyproconazole determination was investigated. Wood flour from four wood species, namely Japanese cedar, Japanese larch, Yezo spruce and Western hemlock, were treated with Tanalith CY containing copper oxide and cyproconazole as active ingredients. About 1 g of the treated flour was extracted for 2 hours in an ultrasonic bath with 10-50 ml of methanol containing tebuconazole that was used as an internal standard. Methanol extracts were removed with a solid-phase extraction cartridge (Oasis MCX) and finally cyproconazole and tebuconazole were collected. These azoles were then dissolved in a mobile phase for the HPLC analysis and concentrations of the azoles were determined using the software that came with the HPLC system. The results of the HPLC analysis indicate that solid-phase extraction is useful for removing wood extractives that hinder cyproconazole determination. The results also suggest that the volume of methanol solution for cyproconazole extraction from treated wood does not affect cyproconazole determination when tebuconazole is used as the internal standard. Ten ml of methanol is sufficient to get reproducible results for one gram of wood flour.

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