Browsing by Author "Kyökari, Mikko Matias"

The literature part of the thesis gives an overview of the occurrence, properties, biological activities, and analytical approaches used for the quantification of resin acids and their derivatives in tree resins, with the emphasis being on a balanced discussion of specific analytical merits and limitations. The quantification of resin acids is challenging due to their isomeric nature and limited stability, with these marker compounds being sensitive to light, oxygen, and strong acids. Methods employing reversed phase liquid chromatographic (LC) approaches in combination with UV/Vis, fluorescence, and mass spectrometric (MS) detection are covered. Gas chromatographic (GC) approaches, involving various derivatization schemes, are discussed, with detection being typically achieved by flame ionization (FI) and MS. Less frequently employed protocols, utilizing zone capillary electrophoresis with cyclodextrin additives and UV and/or fluorescence detection (FLD) are reviewed. Finally, emerging protocols employing supercritical fluid chromatography in combination with FI and MS detection are outlined. Baseline resolution of all major resin acids can only be readily achieved with GC and supercritical fluid chromatography (SFC) methods, while LC and CE protocols suffer from partial peak overlap. In terms of practical convenience, SFC may provide currently the most favorable analytical approach, obviating the need for derivatization and allowing for superior sample throughput. The objective of the experimental part of the thesis was to develop robust and expediate HPLC/UV methods for the detection and quantification of selected active marker compounds, i.e., vanillin, p-coumaric acid, pinoresinol and dehydroabietic acid, in Norwegian spruce resin extracts. Emphasis was placed on obtaining protocols characterized by operational simplicity and ready transferability to production settings. The developed methods involved continuous hot extraction of milled resin samples with 96% EtOH, followed by a simple filtration step and isocratic reversed phase HPLC/UV analysis. A preliminary validation of the developed reversed phase HPLC/UV methods was carried out to assess the limits of detection and quantification (LOD and LOQ); calibration linearity/range; precision and accuracy. LOD and LOQ values were lower than 3 µg/mL and 8.5 µg/mL for all quantified active marker compounds, respectively. To demonstrate the applicability of the developed methods, two batches of Norwegian spruce resin samples were analyzed in three replicate samples.