Ortwin Bobleter

High-performance liquid chromatographic elution behaviour of alcohols, aldehydes, ketones, organic acids and carbohydrates on a strong cation-exchange stationary phase

Abstract The high-performance liquid chromatographic separation of alcohols, aldehydes, ketones, carboxylic acids and carbohydrates on a polystyrene-based strong cation-exchange resin is described. The column temperature was found to be a very important parameter for optimizing separations of these substances. The effect of different functional groups on the elution behaviour is discussed.

Hydrothermolysis — a new process for the utilization of Biomass

SummaryIn the present paper a hydrothermolysis apparatus is described. The reaction vessel is of the percolator type with a volume of 560 cm3 and permits the hydrolysis of biomass materials up to 100 g. The optimum degradation conditions of pure cellulose (filter paper) were determined in dependence on temperature, flow rate of the eluting water and influence of stirring on the reaction mixture. Up to 52% glucose can be obtained by hydrolysing cellulose with pure water at 265°C at a flow rate of 12 cm3/min.Biomass materials such as poplar wood and wheat straw were hydrolysed in two stages, using temperatures of about 200°C for the easily hydrolysable polysaccharides and about 260°C for the polysaccharides, which are more difficult to hydrolyse. In the first stage on an average 45% of the initial amount is converted into soluble products, whereas in the second stage this value amounts to 48%.

Proanthocyanidins: target compounds as antibacterial agents.

Grape seeds accumulate in huge quantities as byproduct during wine production and are therefore a cheap source for pharmacologically active agents. However, studies prove poor antibacterial activity, and results of analyses are sometimes contradictory. The aim of this study was, thus, to determine the antibacterial activity of grape seed extracts with special focus on the chromatographic characterization of active fractions. In the course of these investigations, extraction protocols were optimized so that microwave-assisted extraction (MAE) guaranteed highest preconcentration efficiency. Proanthocyanidins, monomeric flavonoid aglycones, as well as some of their glycosides could be identified within yielded extracts via high-performance liquid chromatography-mass spectrometry (HPLC-MS). By that means the coherence number of possible isomers of procyanidins was approximated by a newly developed equation. As far as antibacterial activity determined via screening tests is concerned, the extracts generally have been found to be positively responsive toward 10 different gram-positive and gram-negative bacteria strains. After fractionation of the raw extracts, proanthocyanidins P2, P3, P4 and gallate esters P2G and P3G (P = proanthocyanidin consisting of catechin and epicatechin units, n = oligomerization degree, G = gallate ester) were determined as active antibacterial agents toward 10 different pathogens. Only moderate activity was found for monomeric flavonoid fractions.

Quantitative studies on furfural and organic acid formation during hydrothermal, acidic and alkaline degradation ofD-xylose

SummaryChromatographic analysis of the degradation ofD-xylose either in plain water or aqueous sulfuric acid at temperatures ranging from 180 – 220°C gave up to 50 mol% of furfural. Activation energies did not differ significantly between reactions in plain water (Ea=119.4 kJ/mol), 0.001M H2SO4 (Ea=120.6 kJ/mol), 0.01M H2SO4 (Ea=130.8 kJ/mol), and 0.1M H2SO4 (Ea=120.7 kJ/mol). However, under alkaline conditions the activation energy was only 63.7 kJ/mol, indicating a different reaction mechanism. Isotachophoretic analyses revealed the formation of pyruvic, formic, glycolic, lactic, and acetic acid. While the relative yields of these acids ranged from 0.8 to 7% under hydrothermal and acidic conditions, 10 – 23% were obtained in alkaline degradation.ZusammenfassungDie chromatographische Analyse des Abbaues vonD-Xylose in reinem Wasser und Schwefelsäure bei Temperaturen von 180 – 220°C ergab die Bildung von bis zu 50 mol% Furfural. In bezug auf die Aktivierungsenergie zeigten sich keine signifikanten Unterschiede zwischen dem Abbau vonD-Xylose in reinem Wasser (Ea=119.4 kJ/mol), 0.001M H2SO4 (Ea=120.6 kJ/mol), 0.01M H2SO4 (Ea=130.8 kJ/mol), and 0.1M H2SO4 (Ea=120.7 kJ/mol). Unter alkalischen Bedingungen hingegen betrug die Aktivierungsenergie nur 63.7 kJ/mol. Dies weist auf einen unterschiedlichen Reaktionsmechanismus hin. Ferner konnte mittels Isotachophorese die Bildung von Brenztraubensäure, Ameisensäure, Glycolsäure, Milchsäure und Essigsäure nachgewiesen werden. Während sich die relativen Ausbeuten in Wasser und Schwefelsäure zwischen 0.8 und 7% bewegten, betrugen sie unter alkalischen Bedingungen 10 bis 23%.

The hydrothermolysis of cellobiose and its reaction-product d-glucose

Abstract The hydrothermolysis of cellobiose in the range 180–249° has been studied. Kinetic analysis of the reaction showed that 60% of the cellobiose is converted into d -glucose, and 40% into other products. The rate ( k 1 ) of cellobiose disintegration is approximately eight times that ( k 2 ) of d -glucose. Thus, hydrothermolysis differs from acidic hydrolysis. Hydrothermolysis is not dependent on pH, at least in the range 3–7.

Separation of phenols, phenolic aldehydes, ketones and acids by high-performance liquid chromatography

Abstract The high-performance liquid chromatographic separation of phenols, benzaldehydes, acetophenones, benzoic and cinnamic acids as well as some related compounds is described. An octadecyl silica column was used with a 0.01 M phosphate buffer-acetonitrile gradient as mobile phase. The retention times of the substances investigated depend on their polarity. An elution order depending on the basic functional groups and the substituents has been established.

Chromatographic analysis of biomass reaction products produced by hydrothermolysis of poplar wood

Abstract Poplar wood was treated under hydrothermal conditions at various temperatures the wide spectrum of reaction products was analysed by different liquid chromatographic methods. Low-molecular-weight compounds were investigated by means of high-performance liquid chromatography. Sugars and sugar decomposition products were analysed using a cation-exchange column; the separation of lignin degradation products was carried out by reversed-phase chromatography with gradient elution. The high-molecular-weight components were characterized by gel permeation chromatography (GPC). Oligomeric sugars were eluted from a gel column with water as the eluent. The molecular weight distribution of degraded lignin was obtained by GPC with a mixture of dioxane—water as the eluent. The application of the methods described does not require a time-consuming sample preparation. Therefore a rapid analysis and quantification of the reaction products is possible. This allows the investigation of the course of reaction and the calculation of the mass balance. In addition, the optimum process parameters can be evaluated from kinetic studies of the hydrothermolysis reaction.

Indirect Electrochemical Reduction of Dispersed Indigo Dyestuff

Iron-triethanolamine complexes are well suited for the indirect reduction of dispersed dyestuffs, e.g., finely dispersed indigo in a dyebath. Experiments to develop basic data for the scale-up of an electrochemical cell usable for the indirect reduction of indigo, vat dyes, and sulfur dyes are described. Planar electrodes show that the current density at the cathode is limited by diffusion controlled transport phenomena in the mediator system. The characterization of the iron triethanolamine mediator system is performed by reduction experiments in a divided flow cell with parallel geometry. An optimization of this cell type was achieved with three-dimensional flow through electrodes, leading to high specific electrode areas and a good space/time yield with the investigated electrochemical system. The characterization of the different cell types was performed with electrolysis experiments using the mediator alone and in the presence of dispersed indigo dyestuff

GC-MS and HPLC analyses of lignin degradation products in biomass hydrolyzates

ZusammenfassungDie gas-chromatographische Trennung von Ligninabbauprodukten nach hydrolytischer Spaltung von Biomasse (z.B. Pappelholz) sowie die massenspektrometrische Identifizierung werden beschrieben. Für eine routinemäßige Analytik der Ligninabbauprodukte in Biomassehydrolysaten wird weiterhin die Trennung mittels einer Gradienten-HPLC-Methode aufgezeigt. Die Detektion erfolgte bei 280 nm. Neben Referenzproben wurden hydrothermale Abbaulösungen untersucht.SummaryThe gas-chromatographic separation of lignin degradation products of hydrolytically degraded biomass (e. g. poplar wood) and their mass spectrometric identification are described. For routine analysis of lignin degradation products of biomass hydrolyzates, a time saving HPLC gradient method using a UV-detection system (280 nm), is described. In addition to reference samples, solutions of hydrothermally degraded biomass were analyzed.

Influence of biomass degradation products on the fermentation of glucose to ethanol by Saccharomyces carlsbergensis W 34

SummaryThe experiments on the fermentation of glucose to ethanol were carried out using the yeast Saccharomyces carlsbergensis W 34. The fermentation time could be reduced to 6 hours. Biomass degradation products such as cellobiose, dihydroxyacetone, glyceraldehyde, showed no or little effect on the fermentation rate. Hydroxymethylfurfural, furfural, methylglyoxal and lignin compounds such as phenol and vanillin inhibit the fermentation in the 1 to 10 mg/mL range very decisively.