Complex formation thermodynamics electrical conductivity

The formation of complex ions is an important problem for the study of the structure and properties of molten salts. Several physicochemical measurements give evidence of the presence of complex ions in melts. The most direct methods are the spectroscopic methods which obtain absorption, vibration and nuclear magnetic resonance spectra. Also, the formation of complex ions can be demonstrated, without establishing the quantitative formula of the complexes, by the variation of various physicochemical properties with the composition. These properties are electrical conductivity, viscosity, molecular refraction, diffusion and thermodynamic properties like molar volume, compressibility, heat of mixing, thermodynamic activity, surface tension. 

Ion-pair chromatography is also suited for the analysis of metal complexes. For their chromatographic separation, the complexes must be thermodynamically and kinetically stable. This means that complex formation must be thermodynamically possible and furthermore an irreversible process. Metal-ETDA and metal-DTPA complexes exhibit a corresponding high stability. To separate the Gd-DTPA complex (Fig. 5-21), which is of great relevance in the pharmaceutical industry, TBAOH was used as the ion-pair reagent [36], Detection was carried out by measuring the electrical conductivity in combination with a suppressor system. 

Substantial part of my scientific activity was devoted to physicochemical properties of aqueous solutions of citric add and various inoiganic citrates. They included formation of metal-mixed complexes, determinations of solubiUties, vapour pressures of water above citric acid and citrates solutions, densities, melting points, sound velocities and electrical conductances. Unquestionably, the industrial and biological importance of citric acid was the main motivation that more than 25 sdentific papers I pubhshed together with my coworkers on systems with citrate ions. Our results up to 1994,1 summarized in the review entitled Thermodynamic and Transport Properties of Aqueous Solutions of Hydroxycaiboxylic Acids. The current book came as a desire to enlarge the information about citric acid properties presented there, to incorporate some subjects which were entirely omitted (chemistry of citric acid and properties of inorganic citrate solutiorrs) and finally to include our and others new relevant results. 

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