Chemometric optimization of derivatization reactions prior to gas chromatography-mass spectrometry analysis.

Derivatization is a methodological technique that can be used to make an organic compound more suitable for qualitative and/or quantitative analysis (e.g. pharmaceuticals).

Heterogeneous structure of O-Antigenic part of lipopolysaccharide of Salmonella Telaviv (Serogroup O:28) containing 3-Acetamido-3,6-dideoxy-D-glucopyranose.

The O-polysaccharide of Salmonella Telaviv was obtained by mild acid degradation of the lipopolysaccharide and studied by chemical methods (sugar and methylation analyses, Smith degradation, de-O-acetylation) and NMR spectroscopy. The structure of the O-polysaccharide was established. The repeating units that are proximal to the lipopolysaccharide core region mostly have a digalactose side chain and lack glucose, whereas those at the other end of the chain mostly do bear glucose but are devoid of the disaccharide side chain.

Application of spectroscopic methods for structural analysis of chitin and chitosan.

Chitin, the second most important natural polymer in the world, and its N-deacetylated derivative chitosan, have been identified as versatile biopolymers for a broad range of applications in medicine, agriculture and the food industry. Two of the main reasons for this are firstly the unique chemical, physicochemical and biological properties of chitin and chitosan, and secondly the unlimited supply of raw materials for their production. These polymers exhibit widely differing physicochemical properties depending on the chitin source and the conditions of chitosan production.

Determination of the pattern of acetylation of low-molecular-weight chitosan used in biomedical applications.

The microstructure of chitosan, a linear copolymer of glucosamine and N-acetylglucosamine units widely used in biomedical applications, is closely dependent on the conditions of its preparation. Knowledge of the structural differences between chitosan preparations is very important in determining the properties of chitosan and essential for structure-activity analysis where biological systems are concerned. Determination of the pattern of acetylation of chitosan samples (P(A) parameter) by (13)C NMR spectroscopy hitherto required depolymerization of the native chitosans.

Smith degradation of the O-antigenic polysaccharide of Salmonella Dakar: structural studies of the products.

Two different oligosaccharides were obtained from the Smith degradation of the O-polysaccharide isolated from the lipopolysaccharide of Salmonella Dakar. The structures of these oligosaccharides were investigated by chemical analysis, NMR spectroscopy and MALDI-TOF mass spectrometry. The following structures of these products were determined: alpha-D-GalpNAc-(1-->4)-alpha-D-Quip3NAc-(1-->3)-alpha-L-Rhap-(1-->2)-threitol and [Formula: see text] where Quip3NAc is 3-acetamido-3,6-dideoxyglucose.

The structure of the O-polysaccharide isolated from the lipopolysaccharide of Salmonella Dakar (serogroup O:28).

The structure of the O-antigenic part of the lipopolysaccharide (LPS) of Salmonella Dakar was analysed using chemical methods, NMR spectroscopy and mass spectrometry. The following structure for the repeating unit of the O-polysaccharide was determined: [see text] where Quip3NAc is 3-acetamido-3,6-dideoxyglucose. This is the first published structure of the O-polysaccharides from 101 serotypes of Salmonella bacteria belonging to serogroup O:28 (formerly M) in the Kauffmann-White scheme.