Shigeo Umetani

Multielemental Determination of GEOTRACES Key Trace Metals in Seawater by ICPMS after Preconcentration Using an Ethylenediaminetriacetic Acid Chelating Resin

GEOTRACES is an international research project on marine biogeochemical cycles of trace elements and their isotopes. GEOTRACES key trace metals in seawater are Al (8-1000 ng/kg), Mn (4-300 ng/kg), Fe (1-100 ng/kg), Cu (30-300 ng/kg), Zn (3-600 ng/kg), and Cd (0.1-100 ng/kg), of which global oceanic distribution will be determined on a number of research cruises. This work introduces a novel method of solid-phase extraction to determine Al, Mn, Fe, Co, Ni, Cu, Zn, Cd, and Pb in seawater by adjusting the pH of the sample to 6 and carrying out a single preconcentration step. The trace metals were collected from approximately 120 mL of seawater using a column of a chelating resin containing the ethylenediaminetriacetic acid functional group and eluted with approximately 15 mL of 1 M HNO3. Mn and Fe in the eluate were measured by inductively coupled plasma mass spectrometry (ICPMS) using the dynamic reaction cell mode, and the other metals were measured using the standard mode. Using this procedure, the trace metals were collected quantitatively, while >99.9% of alkali and alkaline earth metals in seawater were removed. The procedural blank was <7% of the mean concentration in deep ocean waters, except 16% for Pb. The overall detection limit was <14% of the mean concentration in deep ocean waters. The RSD was <9%. Our values for the trace metals in the certified reference materials of seawater NASS-5 and nearshore seawater CASS-4 agreed with the certified values (except that there is no certified value for Al). This method was also successfully applied to the reference materials of open-ocean seawater produced by the SAFe program. Our Fe concentrations were 5.9 +/- 0.7 ng/kg for surface water (S1) and 50.4 +/- 2.9 ng/kg for deep water (D2), which are in agreement with the interlaboratory averages of 5.4 +/- 2.4 and 50.8 +/- 9.5 ng/L, respectively. The data for other metals were oceanographically consistent.

Room-temperature fluorescence, phosphorescence and crystal structures of 4-acyl pyrazolone lanthanide complexes: Ln(L)3·2H2O

Abstract A series of ternary mixed ligand 4-acyl pyrazolone lanthanide complexes: Ln(L)3·2H2O [where Ln = Tb3+ or Gd3+, L = 1-phenyl-3-methyl-4-acetyl-pyrazolone-5 (PMAP), 1-phenyl-3-methyl-4-propionyl-5-pyrazolone (PMPP), 1-phenyl-3-methyl-4-isobutyryl-5-pyrazolone (PMIP), 1-phenyl-3-methyl-4-neovaleryl-pyrazolone-5 (PMNP) and 1-phenyl-3-methyl-4-benzoyl-pyrazolone-5 (PMBP)] were synthesized and characterized by FT-IR spectra, UV-vis spectra and DTA-TG analysis. Room-temperature phosphorescence was observed from the Gd3+ complexes by excitation of the sample with the fourth harmonic frequency of a Nd: YAG laser beam (γ = 266 nm) and the triplet energies of the pyrazolone ligands were evaluated. Both the fluorescence intensity and fluorescence lifetime of the Tb3+ complexes depend on the structure of the ligands and explanations are presented. The crystal structure [Tb(PMPP)3·2H2O]·EtOH was determined by X-ray diffraction. The structure was refined to R = 0.064 (Rw = 0.073). The complex is mononuclear and the central terbium ion is coordinated by eight oxygen atoms to form a square-antiprism coordination polyhedron, six of which are from the three bidentate pyrazolone ligands and the other two are from the two coordination water molecules.

The solvent extraction of europium and barium with 1-aryl-3-methyl-4-aroyl-5-pyrazolones

Abstract Eleven 1-aryl-3-methyl-4-aroyl-5-pyrazolone derivatives were synthesized. Their acid dissociation constants were determined spectrophotometrically; there was a linear relationship between them and Hammetts σ values. Europium and barium ions were readily extracted into benzene and n-octyl alcohol, respectively, at very low pH.

Liquid-liquid extraction of lanthanides with a highly acidic extractant, 3-phenyl-4-benzoyl-5-isoxazolone, in the presence and absence of tri-n-octylphosphine oxide

A highly acidic β-diketone, 3-phenyl-4-benzoyl-5-isoxazolone (HPBI), was synthesized and the acid dissociation constant and the partition constant between an organic solvent and 0.1 M sodium perchlorate solution were determined by a liquid-liquid distribution method. The extraction of lanthanides with HPBI was investigated in the presence and absence of tri-n-octylphosphine oxide. HPBI was found to be a very powerful extractant for lanthanides owing to its strong acidity. The acidity and extractability are discussed on the basis of the molecular structure optimized by a semi-empirical MNDO/H calculation.

Solvent extraction of alkaline earth metals, and lithium with 1-phenyl-3-methyl-4-acylpyrazol-5-ones and trioctylphosphine oxide

The synergic extraction of magnesium, calcium, strongium, barium and lithium into cyclohexane or benzene containing 1-phenyl-3-methyl-4-acyl-pyrazol-5-one (HA) and tri-n-octylphosphine oxide (TOPO) was investigated as a function of pH, HA and TOPO concentration. The extracted species when the 4-benzoyl compound was used, were MA2(TOPO)2 (M = Mg, Ca, Sr), BaA2(TOPO)3 and LiA(TOPO)2. When the 4-trifluoro-acetyl derivatives was used, the extracted species were the same except for SrA2(TOPO)3. Extraction constants for the synergic extractions were calculated.

Adduct formation properties of mono- and bidentate phosphine oxide compounds in the liquid—liquid extraction of some divalent metals with 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone

Abstract The bidentate phosphine oxide compounds bis(diphenylphosphinyl)methane (BDPPM) and bis(diphenylphosphinyl)ethane (BDPPE) were synthesized and the liquid—liquid extraction equilibria of some divalent metal ions such as Co(II), Ni(II), Zn(II) and Cd(II) with 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (HPMBP) and the neutral phosphine oxide compounds were investigated. BDPPM was found to be much more powerful than BDPPE and the monodentate neutral ligand trioctylphosphine oxide (TOPO). The composition of the extracted species were determined by a graphical method to be M(PMBP)2(TOPO)s (s = 2 for Co, Ni, Cd and s = 1 for Zn), M(PMBP)2(BDPPM) and M(PMBP)2(BDPPE). The adduct formation constants between the acylpyrazolone chelates and the neutral ligands were determined and are discussed in terms of the molecular structure.

Oxidation of ascorbate and ascorbic acid at the aqueous|organic solution interface

An electron transfer reaction between ascorbate in an aqueous solution and oxidizing agents in an organic solution immiscible with water has been studied for the first time by polarography for charge transfer at the interface between two immiscible electrolyte solutions. A reversible electron transfer polarogram at the aqueous|organic solution interface could be observed when teterachlorobenzoquinone, dibromobenzoquinone and Meldolas Blue were used as oxidizing agents in the organic solution. The oxidation reaction of ascorbate at the aqueous|organic interface was discussed comparing with the reactions at the ordinary electrodes and in homogeneous solutions. The half-wave potentials of electron transfer polarograms at the aqueous|nitrobenzene interface were applied to evaluate the formal redox potential of ascorbate/ascorbate free radical.

The substitent effect on the synergic extraction of europium and scandium with 1-phenyl-3-methyl-4-acylpyrazol-5-one and tri and tri-n-octylphosphine oxide

Abstract The substituent effect of several 1-phenyl-3-methyl-4-cacylpyrazol-5-ones on the adduct formation between their europium and scandium chelates and tri-n-octylphosphine oxide (TOPO) in benzene was studied by liquid—liquid extraction. The europium acylpyrazolonates react with TOPO to form an adduct of the EuR3L type for an aliphatic group and the EuR3L2 type for aromatic and trifluoromethyl groups. The stability of the adducts increases in the order aliphatic s aromatic s trifluromethyl. A steric effect of the terminal group on adduct formation was observed for 2-, 3-, and 4-methyl-substituted benzoylpyrazolonates of europium and especially scandium.

Cooperative intramolecular interaction of diazacrown ether bearing β-diketone fragments on an ionic liquid extraction system

A novel extractant beta-diketone-substituted diaza-18-crown-6 demonstrated very efficient extraction of Sr(2+) due to an intramolecular synergistic effect on the ionic liquid extraction system and recovery of Sr(2+) from the ionic liquid was successfully achieved under acidic conditions.

Solvent extraction of lithium and sodium with 4-benzoyl or 4-perfluoroacyl-5-pyrazolone and TOPO

The synergic solvent extraction of lithium and sodium into benzene or cyclohexane with 4-benzoyl or 4-perfluoroacyl-5-pyrazolone and trioctylphosphine oxide (TOPO) has been investigated. Quantitative extraction (>99%) of lithium, which is one of the most poorly extractable metal ions, can be achieved with 1-tolyl-3-methyl-4-perfluoroacyl-5-pyrazolone and TOPO. The extraction of sodium is somewhat poorer than that of lithium under the same conditions. The perfluoroacyl group at the 4-position of the pyrazolone ring enhances the extraction and increases the maximum percentage extracted. Cyclohexane is found to be suitable for a quantitative extraction as an organic phase when the reagents are soluble in it. Improved separation of lithium and sodium can be attained when they are extracted into benzene.