Liquid-liquid distribution method has been applied for the determination of the composition and stability constants of mercury species with L-cysteine /H2L/. In the pH range 2–8, mercury /II/ forms a complex Hg/HL/2 with very high stability constant /lg
2 = 40.0/, whereas methylmercury and phenylmercury form complexes CH3HgHL /lg
1 = 15.56/ and C6H5HgHL /lg
1 = 16.5/. At pH13, anionic complexes HgL
2 = 42.7/, CH3HgL– /lg
1 = 16.58/ and lg
1 = 17.7 are formed.
Stability and distribution constants of thallium(I) ethyl, n-propyl, isopropyl, n-butyl, isobutyl and sec-butyl xanthates have been radiometrically determined using ion-exchange and extraction methods. The length of the alkyl chain influences the distribution constant, however, it has only a small effect on the stability constant.
The automated modification of the radioanalytical determination of lead and beryllium using AutoAnalyzer modules has been
developed. The method for lead determination is based on a two-phase isotope exchange of lead between the sample solution
labelled with212Pb and the standard lead diethyldithiocarbamate solution in carbon tetrachloride. For the determination of beryllium a substoichiometric
isotope dilution method using7Be as tracer and acetylacetone in chloroform as extractant was used. As little as 0.02 μg/ml of lead and 2 μg/ml of beryllium
can be determined by the methods above. The flow diagrams of the automated procedures are presented.
Liquid-liquid distribution of cadmium between pyridine solution in benzene and aqueous phase containing iodide has been radiometrically investigated, in order to develop a simple method for the study of complexation of cadmium in aqueous solutions. The degree of complexation of cadmium can be determined from the decrease of the distribution ratio in the presence of complexing agents forming non-extractable complexes with this metal. The method was verified for the determination of the composition and stability constants of cadmium with acetate, tartrate, oxalate and glycolate anions and applied for the study of complexation of cadmium in natural waters.
Liquid-liquid distribution method has been applied for the investigation of the complex formation of phenylmercury cation with different amino acids. It has been found that the stability constant of phenylmercury cysteinate is eight order higher in comparison with those of phenylmercury complexes with other amino acids which enables to develop a selective radioreagent method for the determination of submicrogram amounts of cysteine. The method is very simple because it consists in one minute shaking of labelled phenylmercury bromide in an organic solvent with an aqueous sample of cysteine and in the measuring of the radioactivity of the aqueous phase.
Stability and distribution constants of thallium(I) chelates with diethyl-(I), pyrrolidine- (II), piperidine- (III), phenylethyl- (IV) and methylphenylethyldithiocarbamate (V) have been radiometrically determined using ion-exchange and solvent extraction methods. Stability constants of individual chelates do not change considerably, however, the distribution constants of neutral chelates increase in the order II<IV<IIII<V.
Algal nets of Hydrodictyon reticulatum have been cultivated in double or triple labelled medium as to investigate the change of the intracellular concentration and membrane transport of chloride, sulphate, phosphate and sodium ions. The change of the intracellular concentrations of potassium and ammonium ions has been studied using atomic absorption and spectrophotometric methods, respectively. The release of different ionic species from algal cells should be always taken into account during the membrane transport studies.
Algal nets of Hydrodictyon reticulatum have been cultivated in the radioactivity labelled medium of different chemical composition. It has been found that the intracellular concentration of sodium, potassium, ammonium, chloride, sulphate and phosphate ions changed in a great extent in the dependence of the experimental conditions. The influx of cations from neutral chloride solutions decreases in the order: ammoniumpotassium, thallium/I/
rubidium>cesium>lithiumsodium ions. The intracellular chloride ions can be reversible displaced by bromide or sulphate anions.
A new radioanalytical method has been developed based on homogeneous isotopic exchange in the organic phase. The theory of
the method is presented and discussed. This method has been applied for the simple, selective and rapid determination of bismuth
based on the isotopic exchange between bismuth diethyldithiocarbamate and bismuth iodide complex labelled with210Bi. As little as 0.01 μg of the metal can be determined.
Cumulation factors of 44 species of 32 elements, determined mainly using radiometric methods, are summarized. On the basis of experimental results obtained, general conclusions on the influence of specific surface of algal cells, on the charge and the concentration of species studied, on the pH-value and on the concentration of other metal salts and complexing agents are drawn.