A method is described for the quantitative analysis of seven known compounds, specifically plicatic acid, thujaplicatin methyl ether, beta-thujaplicin, gamma-thujaplicin, beta-thujaplicinol, thujic acid, and methyl thujate, in the ethanol extract of second growth western redcedar heartwood (Thuja plicata Donn) by high-performance liquid chromatography using diode array detection. The para bromo phenacyl ester of crotonic acid is synthesized for use as the internal standard for the method. Separation of compounds covering a wide range of polarities is achieved using an Inertsil ODS 3 3-micro column. Twenty seven second growth trees ranging in age from 40 to 125 years, originating from the coastal and interior regions of British Columbia, are selected for analysis and profiled using the described method. Samples consisting of five growth rings each are analyzed from the heartwood-sapwood boundary to the pith for each tree. Substantial variation in most heartwood compounds are detected within and between trees within a region. Significant variation in beta-thujaplicin, the ratio between gamma- and beta-thujaplicin, and methyl thujate is detected between coastal and interior populations.
Western red cedar (Thuja plicata Donn) heartwood samples were extracted in methanol. Reverse-phase HPLC with UV detection was used for extractive separation and analysis. Six major extractives were quantified by comparing analyte response with the response factor of an internal standard using single-point calibration. The limit of detection of the method was estimated as (mg ml -1 ): (-)-plicatic acid, 0.6; g-thujaplicin, 3.0; b-thujaplicin, 3.0; b-thujaplicinol, 3.0; thujic acid, 0.6; and methyl thujate, 1.2. Yields were 36% higher for powdered than for sliced samples. A temperature of 48C during ultrasonication yielded 16% more (-)-plicatic acid than in non-cooled extractions, but did not significantly increase yields for the remaining five compounds. The recovery and repeatability of the extraction method were assessed by adding the aromatic compounds methoxyhydroquinone and 2-acetonaphthone to heartwood samples before extraction. The recovery yield was ;90% with ;5% variability.
A solution of internal standard in acetonitrile is used to extract samples of wood from lumber which had been commercially treated with chlorinated phenols. The tetrachlorophenol(TCP) and pentachlorophenol( PCP) were analytically separated from each other and from the other wood extractive compounds using a high performance liquid chromatograph (HPLC). The ultraviolet (UV) absorptions of the TCP, PCP, and internal standard were automatically measured as they eluted. The UV absorption peaks were integrated, and the amounts of TCP and PCP present were calculated with a dedicated microcomputer. Compared with the method previously used, this method is faster (up to 144 samples per 48 hours), has the same accuracy and precision, and it is linear over the concentration range used.
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