Extraction with long-chain amines-X Complexometric determination of titanium after extraction of its ascorbate complexes

A highly selective extraction of titanium as its ascorbate complexes from slightly acidic medium into trioctylmethylammonium sulphate is described. After stripping into nitric acid, titanium is determined complexometrically. The method allows separation of titanium from large amounts of iron, aluminium and bivalent metals. The procedure for the determination of iron and aluminium after the titanium extraction is also given. The method has been applied to the determination of titanium in special alloys and minerals.     

Flow-injection single-point titration of acids with biamperometric detection at polarized platinum electrodes

Flow-injection single-point titration of acids is based on biamperometric measurement of iodine formed quantitatively in the reaction of iodide with iodate. Results are presented for determination of sulphuric, hydrofluoric, monochloroacetic, formic and acetic acids. The slopes of the calibration plots, which are linear for about 1–10 rum acid, depend on the strength of the acid, decreasing from sulphuric acid to acetic acid. With microcomputer on-line data processing, relative standard deviations were about 0.2%.     

Adsorption and viscoelastic properties of fractionated mucin (BSM) and bovine serum albumin (BSA) studied with quartz crystal microbalance (QCM-D)

The adsorption profile and viscoelastic properties of bovine submaxillary gland mucin (BSM) and bovine serum albumin (BSA), extracted from a commercial mucin preparation, adsorbing to polystyrene surfaces has been studied using quartz crystal microbalance with dissipation monitoring (QCM-D). A significant difference in the adsorption properties of the different proteins was detected; with the BSA adsorbing in a flat rigid layer whilst the mucin adsorbed in a diffuse, highly viscoelastic layer. Subsequent addition of BSA to the preadsorbed mucin layer resulted in stiffening of the protein layer which was attributed to complexation of the mucin by BSA. In contrast, a preadsorbed layer of BSA prevented mucin adsorption altogether. Combined mixtures of mucin and BSA in well defined ratios revealed intermediate properties between the two separate protein species which varied systematically with the protein ratios. The results shed light on the synergistic effects of complexation of lower molecular weight biomolecular species with mucin. The possibility to selectively control protein uptake and tailor the physical properties of the adsorbed layer makes mucin an attractive option for application in biomaterial coatings.     

Kinetics and mechanism of the reaction of novel low spin Fe(II)-azo amino acid complexes with hydrogen peroxide in aqueous solutions and in aqua-methanol binary mixtures

Kinetics of Fe(II)-azo complexes derived from amino acids (DL-phenylalanine, DL-tryptophane, histidine and alanine) and p-nitroso aromatic substituted amines (N,N-dimethylamino-4-nitrosoaniline and N,N-dimethylamino-4-nitrosoaniline) with hydrogen peroxide in the aqueous solutions and under pseudo-first order conditions have been studied. The reaction exhibits two-stage kinetics. The reaction mechanism was proposed and discussed in terms of complex structure, pH and nature of the medium. The activation parameters and pK _a values were evaluated and correlated with the structural effects of the complexes.     

Quantitative EPR study on free radicals in the natural polyphenols interacting with metal ions and other environmental pollutants

Quantitative electron paramagnetic resonance (EPR) method was applied to characterise radicals stabilised in polyphenolic matrices of various biogenic materials: lichens, mosses, composts, soils, peats, brown coals and sewage sludge sediments. The investigations were carried out on raw materials and extracted fractions of humic acids (HA). General trends of g value and spin concentration changes were found. These parameters in lichens strongly depend on lichen species and air pollution. Determination of the g value and semiquinone spin concentration allows to assess degree of transformation of organic matter in compost, soil, peat and lignite. Application of gaseous ammonia as a base penetrating the organic matrices extends the possibilities and usefulness of the method. Interaction of metal ions with humic materials is illustrated by interaction of VO2+ ion with peat and lignite HA as well as demineralised (raw and carbonised) brown coal. Our investigations demonstrate that quantitative EPR is a rapid and effective monitoring method to study the influence of various environmental factors on substances containing polyphenolic matrices.