Elementspeziesanalytik anionischer Aluminium-Carbonsäure-Komplexe mittels Ionenchromatographie

The aim of this work is the separation of several anionic aluminium species by anion exchange chromatography coupled online with atomic emission spectrometry. The benefits of crystallized complex species as reference materials for the species characterization are also shown. Citric acid and aluminium ions built up several anionic complexes. The solution chemistry of three in literature described aluminium citrate complexes (Al3Cit2, Al3Cit2 and AlCit2) was investigated and their different thermodynamic and kinetic behaviour was shown by ion chromatographic separations. The two anionic aluminium malate complexes Al4Malat4 and Al4Malat6 were synthesized and characterized by X-ray techniques. The benefits of those crystalline complexes for the speciation of aluminium malate model solutions by ion chromatography were shown. The species distribution in several models was investigated by varying the pH and the metal-toligand-amount of the solutions. Up to twelve anionic complex ions are presented in solutions containing aluminium ions and tartronic acid. The species distribution in those models depends strongly on pH-variations. Distribution curves in a range from pH 2 to pH 9 and ion charges of the separated aluminium tartronate complexes are given. Their structural characterization is still missing. The speciation of gallium-, iron- and chromium-complexes with citrate and malate ligands was investigated using the IC-ICP-AES technique. The gallium speciation by ion chromatography is still unsatisfactory, but this method can be a useful tool for the speciation of iron- and chromium-complexes. There was no success of using Tiron as photometric reagent for the detection of aluminium by post column derivatization, because this reagent does not react fully with stable or inerte aluminium compexes in short time. Instead, this property can be used for the investigation of thermodynamic and kinetic data of the complexes: It was possible to determine the power of complexation for some carboxylic acids with aluminium ions. Additional the monitoring of the complex decomposition of some dissolved species was carried out with various sample temperatures. The Tiron post column derivatization under different reaction temperatures shows graduated kinetic data of complex decompositions.