Additionally, European oak is an attractive species for various interior and exterior applications. Within the focus to apply substances for wood protections, here fire retardants, with low hazardous and low environmental impact is of interest. The use of internal recovery standards (RSs) was tested the highest recoveries were obtained by direct spiking of the samples with the RS prior to hydrolysis. These experiments confirmed that the hexoses require considerably harsher conditions for complete liberation compared to xylose and arabinose. The carbohydrate degradation was also investigated over time for different dilutions and hydrolysis temperatures. A lower acid concentration led to insufficient liberation of galactose and glucose, while higher acid concentrations led to degradation of arabinose and xylose. The amount of sulphuric acid needed for complete hydrolysis of the carbohydrates was determined in the range of 3.5–5 mol kg −1 of BL. The hydrolysates were then analysed for the four monosaccharides arabinose, xylose, galactose and glucose, by high performance ion chromatography (HPIC) with pulsed amperometric detection. The present paper presents a thorough investigation of quantitative analysis of carbohydrates, by performing acid hydrolysis experiments with a concentrated BL sample of 44% total dry solids. A simple and reliable detection of those is of importance for further processing of the liquor.

Besides lignin and carboxylic acids, this liquor also contains hemicelluloses and their degradation products. Black liquor (BL) from the kraft process is considered a promising feedstock for several biorefinery scenarios.

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