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The main objective of the study is to present a chromatographic method that allows rapid and accurate quality control of extractives in liquid and headspace samples of wood and bark of European silver fir (Abies alba Mill.). The chemical identity of silver fir extractives in liquid and headspace samples was investigated. Mature silver firs were harvested and samples of sapwood, heartwood, knotwood and bark were prepared. Liquid samples were obtained by solvent extraction at higher temperature and pressure, while the volatile extractives of silver fir tissues were collected by headspace sampling. The extractives in the liquid silver fir samples were silylated prior to chromatographic analysis. The samples were then measured using gas chromatography (GC) coupled with a mass selective detector (MSD). The samples were introduced into the GC-MSD system using the Automatic Liquid Sampler (ALS) and the Headspace Sampler (HS). A total of 55 compounds were detected in the silver fir wood and bark samples. The liquid samples consisted of a variety of carboxylic/dicarboxylic acids, sugars with sugar alcohols (inositols) and sugar acids, with citric acid, quininic acid and sucrose being the most frequently represented. The liquid bark samples contained mainly sugar-like compounds, while the knotwood extracts contained large amounts of phenolic compounds and lignans. D-pitinol was confirmed as the most characteristic GC-MSD peak of the silver fir extracts. Analysis of the headspace of silver fir revealed α-pinene, camphene, Dlimonene, β-myrcene, ocimene, 2-bornanone or D-camphor and α-terpineol as the characteristic monoterpenes. It was shown that the presented GC-MSD method is a suitable analytical tool for the chemical screening of lowmolecular weight compounds in both liquid and headspace samples of wood and bark. However, the analysis of higher molecular weight extractives requires a different analytical approach supported by other analytical methods such as LC/MS.

Cilj naše študije je bil razviti več različnih formulacij biokompozitnih in bionanokompozitnih filmov na osnovi polivinil alkohola (PVA) z dodatkom ojačitvene komponente – celuloznih nanofibril (CNF) in različnih tipov biološko aktivnih taninov – taninske kisline (TA), galne kisline (GA) in kostanjevega tanina (KT). CNF smo dodali v utežnem deležu 2 %; TA, GA in KT pa v utežnem deležu 4 % glede na PVA. S 4 % dodatkom TA v PVA matrico smo pripravili biokompozitni film, ki je izkazoval več kot 25 % višjo natezno trdnost v primerjavi z osnovnim PVA filmom. Z dodatkom 2 % CNF in 4 % TA v PVA matrico smo pridobili bionanokompozitni film (P2C4T) z izboljšanim modulom elastičnosti in natezno trdnostjo, hkrati pa smo z omenjenima dodatkoma povečali tudi fleksibilnost pripravljenega nanokompozita, saj je bila vrednost raztezka pri pretrgu za končni formulirani film (P2C4T) več kot 50 % višja od raztezka pri pretrgu za osnovni PVA film. Hidrofilnost površine dvokomponentnih PVA filmov je bila nižja, trikomponentnih pa višja.

In the case of Scots pine (Pinus sylvestris L.), anatomical differences between the sapwood and heartwood were researched, the content of extractives in the sapwood and heartwood defined, hygroscopicity of sapwood and heartwood studied, so as the relationship between the content of extractives and sorption properties. Research was carried out on 6 test trees. Anatomical investigations were performed using the classic light-field microscopy. Investigation of samples for determination of dimensional stability and sorption properties was held by conditioning in the glass-air condition chambers. Samples for chemical analysis were extracted with cyclohexane and a mixture of acetone and water, and the proportion of total phenols was determined by UV-Vis spectrophotometry. The differences between the sapwood and heartwood were in the resin canals, in the lumens of axial tracheids along the rays as well as differences in parenchymal cells and bordered pits. The content of extractives in the heartwood was higher than in the sapwood. Investigations of the sapwood and heartwood did not show statistically significant differences in the density in the absolutely dry state, at the point of saturation of cell walls, in the volume shrinkage, and not in the coefficient of swelling in the radial direction. We found differences between the sapwood and heartwood transverse anisotropy, differential swell in the tangential direction, in the coefficient of swelling in the radial direction and the sorption quotient. These differences can be attributed to mutual effect of the anatomical and chemical characteristics of both types of wood and when interpreting indicators of dimensional stability, the effect of the geometry of incremental layers should be taken into account.

The content and composition of extractives in the wood and bark tissue of black locust (Robinia pseudoacacia L.) were investigated. Wood and bark samples were extracted using a Soxhlet apparatus with acetone. The extracts were gravimetrically examined to measure total hydrophilic extractive content. Total phenolic content was measured colorimetrically with a UV-Vis spectrophotometer. The wood and bark extracts were further investigated using high-pressure liquid chromatography (HPLC) to identify and quantify dihydrorobinetin in the extracts. The contents of total hydrophilic extractives, total phenols and dihydrorobinetin were higher in heartwood than in the sapwood and bark. No relationship was found between the height at which the samples were taken from the stem and the content of soluble components in the wood and bark. The heartwood of black locust represents a rich potential source of phenolic extractives.

Qualitative and quantitative analysis of wood plant extractives depend on the efficiency of the extraction method used. The aim of this study was the application of the accelerated solvent extraction system ASE 350 to obtain hydrophilic extracts form silver fir wood (Abies alba Mill.) and optimization of the extraction protocol. Silver fir trees originated from Kočevska Reka. Dissected and milled samples of sapwood, heartwood and knots were extracted with the ASE 350 with water, ethanol (95 % aq), acetone (95 % aq) and ethyl acetate. The number of extraction cycles was determined. Analysis of extracts was done by UV/Vis spectrophotometry and HPLC. The most effective solvent for the extraction of phenolic components from heartwood was ethanol (95 % aq), in the case of sapwood water and acetone (95 % aq) in the case of knotwood. Only two 5-minute extraction cycles were required for sufficient extraction yield when using ASE 350 at 100 °C and 103.42 bar.

The aim of the study was to prepare a bionanocomposite based on polylactic acid (PLA) with the addition of nanofibrillated cellulose (NFC) as a reinforcement component. For the production of the composite we used unmodified and acetylated NFC (A_NFC). Freeze-dried NFC was acetylated in a heterogeneous system with acetic anhydride in dimethylformamide (DMF) in the presence of pyridine as a catalyst. The success of the acetylation was determined by FT-IR spectroscopy. PLA films were prepared with the addition of 2.5%, 5% and 10% of unmodified and acetylated NFC. The focus of this research was the impact of the NFC additive on the transparency and on the resistance of the bionanocomposite to scratching. The transparency of the bionanocomposite film was measured using UV-Vis spectrophotometry, and the resistance of the films to scratching was evaluated with a scratch test. The optimal amount of NFC and A_NFC added to the polymer PLA to achieve better resistance of the bionanocomposite to scratching was determined. The best resistance of the prepared bionanocomposite to scratching was achieved by the addition of a 2.5% A_NFC to the PLA polymer, which also has minimal reduced transparency with respect to the PLA film. With the highest addition of A_NFC to the PLA polymer, bionanocomposite films with minimal reduction of transparency were obtained.

Common beech (Fagus sylvatica L.) is one of the most widespread and economically important tree species in Europe and, therefore, represents a potential source of high value added extractives. The aim of this paper was, therefore, to review the existing data regarding the composition of lipophilic and hydrophilic extractives of beech tissues, and the extraction systems and analytical techniques used for their examination. The lipophilic extractable fraction of beech is characterized mainly by saturated and unsaturated fatty acids, fatty alcohols and sterols while the hydrophilic extractives of beech consist of soluble sugars, i.e. monosaccharides, oligosaccharides, sugar alcohols and sugar acids, as well as of simple phenols and flavonoids. Chromatography has been recognized as the convenient and most frequently used technique for the chemical analysis of extractives. This overview showed that the information about the composition of low-molecular extractives of beech is satisfactory, but the data on oligomeric extractives are still fragmentary.

The most suitable composition of mobile phase for the separation of simple phenolic compounds such as gallic acid, pyrocatechol, phloroglucinol, resorcinol, vanillin and related compound catechin by the high performance liquid chromatography was investigated. The most appropriate developing mobile system for the separation of these organic compounds was acetonitrile and 2% water solution of formic acid with gradient ratio from 2.98 to 25:75. The best separation of the six organic compounds was achieved using mobile phase with lower content of formic acid. HPLC is a method of choice for qualitative and quantitative analysis compounds in various types of samples in the broad field of forestry-wood-pulp-paper chain.

The aim of this research was to examine the content of catechin in normal and traumatic structures of beechwood by high performance liquid chromatography (HPLC). Two discs were sawn from each of six harvested trees. The first disc was taken from the lower, wounded part and the second one from the upper part of each stem. Discs containing the bases of living and dead branches were taken from the crown. Samples of wound-wood, reaction zones, sapwood, as well as living and dead knots, were sampled from discs. Samples were milled and then extracted sequentially by cyclohexane and methanol/water in a Soxhlet apparatus. A method for the separation of catechins from extracts was developed for the present chromatographic investigation. Statistical analysis did not reveal significant differences in total or hydrophilic extractives, nor in the content of catechin among the investigated trees. The content of hydrophilic extractives and catechin were significantly different among the investigated categories of wood tissues. Wound-wood and knot extracts contained the highest amount of this flava-3-ol. Reaction zones contained higher amounts of catechin than discolored wood, but less than sapwood. The extracts of discolored wood showed the lowest amounts of catechin. Sapwood samples that originated from wounded discs exhibited significantly higher contents of catechin than normal sapwood from upper discs. Accumulation of bioactive compound catechin in wound-wood, sapwood and knots is considered to be an important part of the survival strategy of living trees.

The structure of wound-associated wood has been relatively well studied in beech, but only a little information about the occurrence of extractives and particular classes of compounds in these tissues is available. We examined the content of total phenols and variability in their distribution in sapwood, wound-wood and the reaction zones walling-off typical red heart and xylem altered by wounding in two beech trees, using spectrophotometric method. Significant differences in total phenols in different types of beech wood, as well as differences between trees, were confi rmed. Concentrations of total phenols were markedly lower in red heart than in reaction zones and sapwood extracts. The content of total phenols was highest in extracts of the reaction zones formed as a direct response of sapwood to wounding. Differences in the content of total phenols in reaction zones walling-off typical red heart and directly wounded xylem indicate differences in their formation process, in alterations to surrounding tissues and in the characteristics of individual trees.

Discoloration of wood is frequently caused by blue-stain fungi. Among them Aureobasidium pullulans and Sclerophoma pithyophila are reported as the most important staining organism. In previous researches, it was generally considered that blue-stain fungi do not influence mechanical properties. However, there were some opposite results published as well. In order to elucidate this issue, specimens made of Scots pine (Pinus sylvestris) sapwood were exposed to two blue stain fungi A. pullulans and S. pithyophila for periods between two and eight weeks. FTIR, weight, colour and non-destructive modulus of elasticity measurements were performed before and after exposure. The results showed that blue stain fungi, besides considerable discoloration, do not cause any significant damage to wood. Surprisingly the non-destructive MoE analysis showed that modulus of elasticity even slightly increase after fungal exposure.