The extraction of La(III), Gd(III), and Lu(III) with 18-crown-6 (18C6) has been studied using pentadecafluorooctanoate (PDFO) as a counter anion. Very high extractability of La(III) was observed in various organic solvents such as benzene, chloroform, 1,2-dichloroethane, and nitrobenzene. The predominant species extracted into benzene was found to be Ln(PDFO)3 (18C6), and the extraction constants (Kex,s1=[Ln(PDFO)3 (18C6)]org/[Ln3+][PDFO]3[18C6]org) were 1013.12 for La(III), 109.74 for Gd(III), and 109.67 for Lu(III). These values are 1010 times higher than those in the trichloroacetate-18C6 system reported previously. The present PDFO-18C6 system was superior to the picrate- and hexafluoroacetylacetonate-18C6 system for the separation efficiency of light lanthanides(III).
Partition coefficients of Cu(acac)2 were determined in eleven organic solvents-0.10M perchlorate systems. Their magnitude was compared with that of the enol form of Hacac and evaluated by a modified equation based on the regular solution theory. The partition coefficient of the copper (II) chelate has been demonstrated to strongly depend on some specific solute-solvent interactions such as direct coordination to the central metal and hydrogen bonding to the ligand molecules. In the case of chloroform, particularly the specific interaction has been elucidated by an association reaction, for which the equilibrium constant has been determined.
Substoichiometric isotope dilution analysis for the determination of trace iron has been studied by using synergistic extraction of iron(III) with a substoichiometric amount of 4-isopropyltropolone (Hipt) in the presence of an excess of 3,5-dichlorophenol (DCP) in heptane. Optimum conditions for the substoichiometric extraction of iron(III) in g to sub-g levels were examined and the high selectivity for iron(III) toward various metal ions encountered in the analysis of biological materials was confirmed. The present method was applied to a biological reference material (NIES, CRM No.9, sargasso) without any pre-separation and was successfully evaluated. Furthermore, substoichiometric stable isotope dilution mass spectrometry using the present extraction method was also used with the above sample. Applicability and practicability was compared for both substoichiometric methods.
Evidence is obtained to show that the liquidliquid extraction separation of99mTc from99Mo with methyl ethyl ketone, methyl propyl ketone and methyl isobutyl ketone can be transformed into a solid-phase column extraction procedure. The aqueous alkaline99molybdate solution is immobilized on a column of a granular large-pore diatomaceous earch support, which is the neluted with the abovementioned extractants. Rapid and clean separation of99mTc can be with all three solvents. The99mTc can be back-extracted from the organic phase on a column filled with distilled water /or saline/ loaded granular diatomaceous earth /Extrelut®/. The possibility of using the abovementioned procedure as a basis for a new99mTc/99Mo generator concept is envisaged.
The synergic extraction of La(III), Eu(III), and Lu(III) with 2-thenoyltrifluoroacetone (Htta) and triphenylarsine oxide (tpao) in benzene has been studied. The extractability of lanthanoids, Ln(III), is significantly affected by the association of Htta with tpao in the organic phase. The associated species is Htta·tpao and the association constant is determined as 101.63. The intrinsic extraction equilibrium of Ln(III) is analyzed using the free concentration of Htta and tpao. The synergic enhancement is ascribable to the formation of the adduct complexes shown as Ln(tta)3tpao and Ln(tta)3(tpao)2 in the present extraction system. The adduct formation constants determined are very large as expected from the high basicity of tpao.
The synergistic effect on the extraction of thorium(IV) was found by the combination of 2-thenoyltrifluoroacetone (Htta) and 1,10-phenanthroline (phen) or 4,7-diphenyl-1,10-phenanthroline (dpp) as a neutral bidentate ligand. Especially in the presence of dpp (1·10–3M) in benzene, the distribution ratio of thorium(IV) increased by a factor of about 300. Such synergistic enhancement of the extraction was ascribed to the formation of the adduct complex of Th(tta)4(phen) and Th(tta)4(dpp) in the organic phase. The extraction constant and the adduct formation constant were determined and discussed.
A highly precise and accurate method for the determination of minor amounts of iron by substoichiometric isotope dilution
analysis is described. The constant amount of Fe(III) is substoichiometrically extracted with 2·10−4M oxine in chloroform from the aqueous phase of pH 9.2–10.0 containing 6·10−3M tartrate. The interfering ions such as Mn(II), Co(II), Ni(II), Cu(II), and Zn(II), can be removed by the preliminary extraction
of Fe(III) from 7.5M hydrochloric acid solutions into isopropyl ether. The present method has been applied to the determination
of iron in biological standard reference materials, i.e., the NBS Spinach (SRM-1570) and the NIES Pepperbush (SRM No. 1),
and the results obtained are 548±9 ppm (NBS certified value: 550±20 ppm) and 193±4 ppm, respectively.
The substoichiometric isotope dilution analysis for manganese(II) in a synergistic extraction system of a chelating agent and a neutral ligand is described. The substoichiometric extarction is based on a substoichiometric amount of 2-thenoyltrifluoroacetone and an excess of 1,10-phenanthroline. The recommended condition and the reproducibility of the present system were examined. The present method was applied for NBS-SRM tomato leaves and NIES-SRM chlorella, and very good results with high accuracy and precision were demonstrated.
Extraction behaviour of lanthanoid/III/ has been investigated by using 18-crown-6/CR/ as a neutral microcyclic ligand, trichloroacetate/TCA–/ as an anionic counter ion, and 1,2-dichloroethane as an organic solvent. From the equilibrium studies, the extractable complex such as LnCR3+ was found for La/III/, Ce/III/, Pr/III/, Nd/III/, Sm/III/, and Eu/III/ and also the formation of Ln/CR/
complexes was suggested for Tb/III/, Tm/III/, and Lu/III/. The extractability of lanthanoid/III/ steeply decreased with increase in the atomic number. This order of extractability was a reverse trend compared with that in many other extraction systems reported so far. Very high separation factors especially among light lanthanoid/III/ were observed.
Preseparation of lanthanoids by substoichiometric precipitation of calcium oxalate and simple radiochemical separation of lanthanoids by lanthanum oxalate have been developed. They were combined with neutron activation analysis of a marine macro-alga (Laminaria religiosa, brown alga) sample. Quantitative recovery of lanthanoids throughout the procedure was examined by radiotracer technique. Eleven lanthanoids, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Er, Yb and Lu, at 0.7–140 ng g–1 were determined with a relative standard deviation of 1–7% (n=3). Concentrations of lanthanoids in the marine macro-alga were compared with land plant and sea water.