Kenneth Larsson

Uronic and other organic acids in Baltic Sea and Black Sea sediments

Abstract Organic acids were released from marine sediments by acid hydrolysis. Ion-exchange chromatography and GC-MS were used to separate and identify the acids. The major compounds detected were galacturonic, glucuronic, mannuronic, 4-O-methylglucuronic, cellobiouronic, guluronic, glyceric, glycolic, lactic and erythronic acids. Numerous biouronic (sugar-uronic acid compounds) and aldonic acids were also found. The low abundance of uronic acids characteristic of terrigenous plants and the similarity of the biouronic composition to that of marine algae indicate a marine algal source for the acids in the sediment. Results from the Black Sea are compared with those from the Baltic Sea and several diagenetic transformations are discussed.

Anion-exchange chromatography of alditols in borate medium

Abstract The retention data for anion-exchange chromatography in tetraborate solution were determined for 33 alditols and deoxyalditols. The order of elution of 1-deoxy-alditols is related to chromatographic data for the corresponding aldonic acids. For all types of polyhydroxy compounds studied, the distribution coefficient increases with increasing stability and charge of the borate complex. Vicinal hydroxyl groups in gauche conformation have the ability to form strong complexes, provided that the steric conditions are favourable in other respects. The contributions of vicinal hydroxyl groups in anti conformation are much less.

Anion-exchange chromatography of monocarboxylic hydroxy-acids in borate medium

Abstract The formation of borate complexes contributes significantly to the distribution coefficients obtained in the separation of polyhydroxy acids in borate medium. A study of a large number of straight-chain hydroxy acids shows that these contributions tend to increase with the number of vicinal hydroxyl groups and with their distance from the carboxylate group. Vicinal hydroxyl groups in gauche conformation have the ability to form strong complexes, provided that the steric conditions are favourable in other respects. The contributions of vicinal hydroxyl groups in anti conformation are much less.

Isomerization of 4-O-methyl-D-glucuronic acid in neutral, aqueous solution

Abstract Aqueous solutions of 4- O -methyl- D -glucuronic acid at pH 7 were heated at 100°, and the monocarboxylic acids formed by isomerization were separated by anion-exchange chromatography and further identified by gas-liquid chromatography-mass spectrometry. After 6 h, the following yields of acids were obtained: 3- O -methyl- D - lyxo -5-hexulosonic (47%), 3- O -methyl- L - ribo -5-hexulosonic (12%), 4- O -methyl- D -mannuronic (4%), and 3- O -methyl- L - ribo -4-hexulosonic (1%).

Methanolysis of D-galacturonic acid: dimethyl acetals

Dimethyl acetals of galacturono-6,3-lactone and methyl galacturonate are formed during methanolysis of galacturonic acid. The products of methanolysis were studied by ion exchange and gas chromatography. Trimethylsilyl (TMS) derivatives were used in gas chromatography. Structure determinations were made from mass spectra of the TMS derivatives. The course of methanolysis was investigated by means of a gas chromatographic study of the composition of the reaction mixture as a function of time.