G. Bonn

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%.

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.

Ion chromatography of transition metals on an iminodiacetic acid bonded stationary phase

A stationary phase synthesized by covalent binding of iminodiacetic acid to a porous silica support was investigated for the separation of transition metals by ion chromatography. Eluents containing carboxylic acids either alone or in combination with stronger complexing agents were studied in order to examine the elution mechanisms of alkali, alkaline earth and transition metal ions. It was found that both complexation reactions and ion-exchange mechanisms occurred, their rate being governed by the stability of metal complexes. These investigations were used to find optimum conditions for the determination of transition metal ions in alkali and alkaline earth metal-rich matrices, e.g., sea water.

Hepatic but not brain iron is rapidly chelated by deferasirox in aceruloplasminemia due to a novel gene mutation

Background & Aims Aceruloplasminemia is a rare autosomal recessive neurodegenerative disease associated with brain and liver iron accumulation which typically presents with movement disorders, retinal degeneration, and diabetes mellitus. Ceruloplasmin is a multi-copper ferroxidase that is secreted into plasma and facilitates cellular iron export and iron binding to transferrin. Results A novel homozygous ceruloplasmin gene mutation, c.2554+1G>T, was identified as the cause of aceruloplasminemia in three affected siblings. Two siblings presented with movement disorders and diabetes. Complementary DNA sequencing showed that this mutation causes skipping of exon 14 and deletion of amino acids 809–852 while preserving the open reading frame. Western blotting of liver extracts and sera of affected patients showed retention of the abnormal protein in the liver. Aceruloplasminemia was associated with severe brain and liver iron overload, where hepatic mRNA expression of the iron hormone hepcidin was increased, corresponding to the degree of iron overload. Hepatic iron concentration normalized after 3 and 5 months of iron chelation therapy with deferasirox, which was also associated with reduced insulin demands. During short term treatment there was no clinical or imaging evidence for significant effects on brain iron overload. Conclusions Aceruloplasminemia can show an incomplete clinical penetrance but is invariably associated with iron accumulation in the liver and in the brain. Iron accumulation in aceruloplasminemia is a result of defective cellular iron export, where hepcidin regulation is appropriate for the degree of iron overload. Iron chelation with deferasirox was effective in mobilizing hepatic iron but has no effect on brain iron.

High-performance liquid chromatographic elution behaviour of oligosaccharides, monosaccharides and sugar degradation products on series-connected ion-exchange resin columns using water as the mobile phase

Abstract The high-performance liquid chromatographic separation of oligosaccharides, monosaccharides, sugar degradation products and alcohols using a series-connected system of different ion-exchange columns with water as the eluent was investigated. The non-additivity of the number of theoretical plates ( N ), the height equivalent to a theoretical plate ( H ) and the resolution ( R S ) on ion-exchange phases is discussed.

Major flavonoid components of heartsease (viola tricolor L.) and their antioxidant activities

Sephadex LH-20 column chromatography was used to separate flavonoid components in a heartsease methanol extract. One of the main components was identified by NMR as violanthin (6-C-glucosyl-8-C-rhamnosylapigenin). As a first approximation, the other main flavonoid component was considered to be rutin (3-O-rhamnoglucosylquercetin), based on comprehensive comparison of retention times and UV spectra of reference molecules, as well as molecular mass and fragmentation patterns obtained by mass spectrometry. The minor flavonoids were separated by polyamide column and analyzed by LC-MS. The antioxidant capacity of different flavonoid fractions was determined using both Trolox equivalent antioxidant capacity (TEAC) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) in vitro antioxidant assays. The highest electron-donor capacity was found for the major flavonoid component (rutin), whereas one minor component-rich flavonoid fraction exhibited the highest hydrogen-donor activity.

Analysis of heartsease (Viola tricolor L.) flavonoid glycosides by micro-liquid chromatography coupled to multistage mass spectrometry.

Micro-liquid chromatography (microLC) in conjunction with multistage mass spectrometry (MSn) was introduced to study several major heartsease flavonoid glycosides. High-resolution microLC separation was achieved by using a monolithic poly(p-methylstyrene-co-1,2-bis(p-vinylphenyl)ethane) column under reversed-phase conditions. The MS/MS and MS3 analysis of the flavonoid components of interest provided data about their glycosylation type and position, nature of their aglycones, and the structure/linkage information of their glycan moieties. With our microLC-MSn approach, four flavonol O-glycosides, nine flavone-C-glycosides, and three flavone C,O-glycosides were characterized in heartsease methanol extract. All of these glycoconjugates were found to be the derivatives of six aglycones: apigenin, chrysoeriol, isorhamnetin, kaempferol, luteolin, and quercetin.

Poly(7-oxanorborn-2-ene-5,6-dicarboxylate)-coated silica prepared by ring-opening metathesis polymerization for the selective enrichment of radioactive lanthanides

Abstract Block- co -polymers of norborn-2-ene and 7-oxanorborn-2-ene-5,6-dicarboxylate were prepared by ring-opening metathesis polymerization and used for the preparation of poly(norborn-2-ene)- block -(7-oxanorborn-2-ene-5,6-dicarboxylate)-coated silica materials. These sorbents were used for the selective extraction of lanthanides. The coated silicas exhibit an extraordinary good pH stability, are hydrophilic and therefore easily wetable by water alone and show high extraction efficiencies for lanthanides. The use of 200–400 mesh (20–40 μm) materials guarantees a facile handling in terms of back pressure. The extraction efficiencies of the new material for radioactive lanthanides were determined over a concentration range of 20 ng/l–250 μg/ml by the enrichment of Pm-147 and Eu-152 from aqueous solutions. Breakthrough curves, the loading characteristics at different pH-values as well as recoveries for both Pm-147 and Eu-152 were determined by β liquid scintillation counting. The optimum pH for lanthanide extraction was found to be in the range of 3.5–5.5. The high extraction selectivity of the new sorbents for lanthanides was confirmed by recovery, HPLC as well as ICP-OES experiments. These investigations revealed that the retention of potentially interfering metal ions such as Mg 2+ , Ca 2+ , Ba 2+ , Mn 2+ , Co 2+ , Ni 2+ , Al 3+ , Fe 3+ , Zn 2+ by the new sorbent was less than 5% in all cases. Actinides such as UO 2 2+ and Th 4+ are quantitatively coextracted by the resin, yet do not interfere in β liquid scintillation counting.