Acid fraction evolution in wood extractives of Pinus pinaster Ait.

The changes in the acid fraction of wood extracts from Pinus pinaster Ait. have been studied. Qualitative and quantitative compositions have been determined in samples that were just extracted and then seven and twelve months after extraction. Samples were prepared according to Technical Association of Pulp and Paper Industry Standards, extracted with petroleum ether (b.p. 40-60 °C) in a Soxhlet apparatus and saponified with ethanolic 0.4N potassium hydroxide. The acid fraction was methylated with diazomethane, and its qualitative composition was determined by combined gas chromatography/mass spectrometry. The quantitative composition was determined by gas chromatography with a DEGS packed column. An increase was observed in the percentage of palmitic, oleic, pimaric and dehydroabietic acids, and there was a decrease in the percentage of linoleic and abietic acids. No variation was observed in extract composition after seven and twelve months.