Studies of the solvent extraction of indium oxinate

An investigation of the extraction of radio-labelled 2.10^-5M indium from various aqueous solutions into a number of organic solvents containing oxine has been carried out. The effects of pH value, oxine concentration, masking agents, different organic phases, and temperature have been studied. Extraction constants and pH values of 50% extraction have been measured and compared with theoretically-calculatud values.     

OPTICALLY DETECTED MAGNETIC RESONANCE OF THE TRYPTOPHAN PHOSPHORESCENT STATE IN NATIVE PROTEINS*

Abstract— The phosphorescent triplet state of tryptophan has been studied by the method of optically detected magnetic resonance (ODMR) at pumped helium temperatures in zero magnetic field. Only one of the triplet sublevels is found to be significantly radiative; the other two decay radiationlessly. Although the phosphorescence and ODMR decay lifetimes are influenced by spin–lattice relaxation processes at T = 1.3°K, the lifetime of the radiative level can be estimated as approximately 2 s, whereas the lifetimes of the non–radiative levels are in excess of 10 s. Comparison of the ODMR signals and the phosphorescence spectra has been made for tryptophans in native proteins with the following results: the ODMR signals of the two types of tryptophan sites in horse liver alcohol dehydrogenase can be resolved due to a shift in the D and E values of the respective triplet states; binding of the substrate tri- N -acetylglucosamine to hen lysozyme leads to a considerable narrowing of the phosphorescence peaks and ODMR signals as well as to a shift in the E value of the triplet state.
The following tentative conclusions can be reached: the tryptophan triplet D and E values are measurably affected by the environment of the chromophore in the protein, as are the linewidths of the magnetic resonance transitions. The | E | value is reduced and the magnetic resonance linewidth is increased with increasing exposure of the tryptophan to hydroxylic solvent. Although a considerable part of the width of the magnetic resonance transition can be ascribed to a heterogeneity of environments in the sample, there appears to exist an intrinsic line–broadening process which at present is not understood.     

Adduct formation in the extraction of zinc oxinate into various organic solvents

The extraction of zincoxinate into 10 different organic solvents was investigated. By studying the dependence of the distribution upon pH, reagent concentration, and solvent concentration (in an inert medium), the species were identified and the extraction constants estimated. Correlations between the species type and the efficiency of extraction are postulated. The species extracting into 4-methyl-2-pentanone, I-butanol, and 4-methyl-2-pentanol is ZnR₂S₂, that extracting into benzene and chloroform is ZnR₂(HR)S, that extracting into butyl and pentyl ethers is ZnR₂S, that extracting into carbon tetrachloride is ZnR₂(HR), and that extracting into hexane and cyclohexane is ZnR₂(H₂O)₂. In these formulas, R is the oxinate ion, HR is oxine, and S is the organic solvent. It is suggested that the extraction behavior can be explained by assuming a water molecule to be attached to the ZnR₂S and ZnR₂(HR) species.     

Coprecipitation of cobaltwithnickeldimethylglyoxime

The coprecipitation of cobalt with nickel precipitated as the dimethylglyoxime complex has been investigated under various conditions. Precipitations were carried out in ammonia and acetate solutions, at 25° and 85°, with slow and rapid addition of the solution of the precipitating agent, and with various digestion times. In each experiment, the amount of cobalt was 612 μg and the amount of nickel was 57.6 mg. Of the methods investigated, minimum coprecipitation was achieved by slow addition of ammonia to the acid nickel, cobalt, and dimethylglyoxime solution followed by a 30-minute digestion, all processes being carried out at 25°.     

The solvent extraction of trace antimony(V)

An investigation of the extraction of trace amounts of antimony(V) from aqueous hydrochloric acid solutions into various others and chloroform has been carried out. Before extractions were made, mutual solubility studies of the two-phased systems were conducted. Then extraction experiments were performed using original aqueous acid concentrations from 0 to 12N and non-aqueous phases of ethyl ether, isopropye ether, isoamyl ether, n-hexyl ether, and chloroform. Dielectric constant determinations were made in the equilibrated non-aqueous phases, and spectrophotormetric and salting-out studies were carried out on the ethyl ether system. It was found that the isopropyl ether system presents the most advantageous conditions for the extraction of trace antimony(V)     

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