Bestimmung der Molmassenverteilung sowie der Stabilit�tsgrenze von Polyacrylamiden unter Benutzung einer kombinierten Ausschlu�chromatographie/Kleinwinkel-Laser-Streulichtphotometer Anlage

Kulicke, Werner‐Michael; Böse, N.

doi:10.1007/bf01458961

Cited by 25 publications

(7 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…This might be an indication that some association or aggregation effects were still present within the sample solution. Those structures could then be degraded by the shear force induced at higher concentrations (Kulicke and Bo¨se 1984). However, this should as well led to significant changes of the ratio between light scattering and refractive index signal intensities (Figure 2a, b).…”

Section: Resultsmentioning

confidence: 90%

Studies on pre-hump and main fractions of cellulose-2,5-acetate in acetone

Saake

Zenker

Stein³

et al. 2006

Cellulose

View full text Add to dashboard Cite

Technical cellulose-2.5-acetates (CA 2.5) were characterized regarding their carbohydrate composition in comparison to the raw material. The association of the CA 2.5 samples in acetone was studied by size exclusion chromatography (SEC) using various acetone grades and styrene divinylbenzene copolymer columns. In HPLC grade acetone with and without addition of 1% water up to three different pre-humps eluted in front of the main fraction of the polymer. The evaluation of the main peak by light scattering measurements resulted in high molar masses indicating that for these technical CA 2.5 samples even the main fraction is not dissolved without association. No pre-humps or association phenomena were observed after addition of 1 ppm LiBr to HPLC grade acetone or with p.a. grade acetone. In addition pre-hump enriched and pre-hump free fractions were isolated by fractionated precipitation. The carbohydrate composition of these fractions was determined and correlated with their association pattern in SEC investigations.

show abstract

Section: Resultsmentioning

confidence: 90%

Studies on pre-hump and main fractions of cellulose-2,5-acetate in acetone

Saake

Zenker

Stein³

et al. 2006

Cellulose

View full text Add to dashboard Cite

show abstract

“…Light-scattering measurements were performed using a coupled system of various apparatuses consisting of an SEC unit, a multiangle laser light scattering photometer (Dawn DSP; Wyatt Technology Corp., Santa Barbara, CA; ϭ 633 nm), and a concentration detector (Shodex RI-71; Showa Denko, Tokyo, Japan) at 25°C (15,16,18,20). Chitosan samples were dissolved in an eluent (0.1 vol% CF 3 COOH, 0.1 mol/liter NaCl) by shaking (12 h) and polymer solutions (1 mg/ml) were filtered using a 0.45-m membrane filter.…”

Section: Methodsmentioning

confidence: 99%

Genetic Improvement of Bacillus licheniformis Strains for Efficient Deproteinization of Shrimp Shells and Production of High-Molecular-Mass Chitin and Chitosan

Hoffmann

Daum

Köster

et al. 2010

Appl Environ Microbiol

View full text Add to dashboard Cite

By targeted deletion of the polyglutamate operon (pga) in Bacillus licheniformis F11, a derivative form, F11.1 (⌬pga), was obtained that, along with lacking polyglutamate (PGA) formation, displayed enhanced proteolytic activities. The phenotypic properties were maintained in a strain in which the chiBA operon was additionally deleted: F11.4 (⌬chiBA ⌬pga). These genetically modified strains, carrying the ⌬pga deletion either alone (F11.1) or together with the ⌬chiBA (F11.4) deletion, were used in fermentations (20-liter scale) aiming at the deproteinization of shrimp shells in order to obtain long-chain chitin. After chemical deacetylation, the resulting chitosan samples were analyzed by nuclear magnetic resonance spectroscopy, size exclusion chromatography, and viscometry and compared to a chitosan preparation that was produced in parallel by chemical methods by a commercial chitosan supplier (GSRmbH). Though faint lipid impurities were present in the fermented polysaccharides, the viscosity of the material produced with the double-deletion mutant F11.4 (⌬pga ⌬chiBA) was higher than that of the chemically produced and commercially available samples (Cognis GmbH). Thus, enhanced proteolytic activities and a lack of chitinase activity render the double mutant F11.4 a powerful tool for the production of long-chain chitosan.Chitin {poly [␤-(134)-N-acetyl-D-glucosamine]}, a polysaccharide common to fungal cell walls and insect and crustacean carapaces, is-second only to cellulose-one of the most abundant natural polymers; it serves as the precursor of chitosan, a deacetylated derivative with numerous applications, e.g., in pharmaceuticals, cosmetics, and dairy products and in wastewater treatment, agriculture, and many other technological processes. Routinely, such applications require specific structural attributes, and the effectiveness and value of chitosan depend on its molecular weight and degree of deacetylation (21,27). Depending on the source and preparation, the physicochemical properties of chitin and chitosan may vary drastically (6); therefore, structural analysis of chitosan products is of the utmost importance.Procedures currently used to purify and transform chitin into chitosan (almost exclusively from shrimp shells) involve harsh chemical treatments accompanied by uncontrollable hydrolysis and chemical modifications, eventually resulting in the formation of undesired by-products such as irregularly deacetylated polymers (51). Since the removal of proteins and calcium carbonate by alternating acid and alkali treatments collaterally yields large amounts of aqueous waste, bioconversion is also desirable from the ecological point of view.As for the above-mentioned chemical procedures, biotechnological processes for chitin recovery follow the same rules of action (12); however, chemical demineralization and deproteinization approaches are replaced by fermentation steps using appropriate microorganisms. Due to the lack of harsh chemical agents, there is not only a considerable reduction of expenses for was...

show abstract

“…Dariiber hinaus treten in Schuttungen von porosen Kugeln, wie sie bei der AusschluR-Chromatographie fur die Bestimmung der Molmassen-Verteilung von Polymeren verwendet werden, starke Dehnstromungen auf. In solchen Dehnstromungen konnen bei den ublicherweise verwendeten DurchfluRraten von 1 ml/min Degradationen der Polymer-Molekule schon bei relativ kleinen Molmassen beobachtet werden, was bislang nicht bekannt war [3]. Es ist daher das Ziel der vorliegenden Arbeit, qualitativ und quantitativ zu untersuchen, unter welchen Bedingungen beim Stromen von Polymer-Losungen in porosen Medien Degradationserscheinungen auftreten.…”

Section: Degradation Von Polymer-molekulen Beim Durchstromen Poroser unclassified

Degradation von Polymer‐Molekülen beim Durchströmen poröser Medien

Hashemzadeh

Kulicke

1986

Chemie Ingenieur Technik

View full text Add to dashboard Cite

Bestimmung der Molmassenverteilung sowie der Stabilit�tsgrenze von Polyacrylamiden unter Benutzung einer kombinierten Ausschlu�chromatographie/Kleinwinkel-Laser-Streulichtphotometer Anlage

Cited by 25 publications

References 35 publications

Studies on pre-hump and main fractions of cellulose-2,5-acetate in acetone

Studies on pre-hump and main fractions of cellulose-2,5-acetate in acetone

Genetic Improvement of Bacillus licheniformis Strains for Efficient Deproteinization of Shrimp Shells and Production of High-Molecular-Mass Chitin and Chitosan

Degradation von Polymer‐Molekülen beim Durchströmen poröser Medien

Contact Info

Product

Resources

About