Sadanobu Inoue

Reversed-phase partition high-pressure liquid chromatography of trace amounts of inorganic and organic mercury with silver diethyldithiocarbamate

Inorganic and organic mercury diethyldithiocarbamates have been separated by reversedphase partition high-pressure liquid chromatography. The mercury chelates were formed by an exchange reaction with silver diethyldithiocarbamate in chloroform, in the presence of acetate buffer (pH 5.0). The inorganic and organic mercury chelates in the extract were separated within 30 min on a 3.9 x 300 mm mu-Bondapak C(18) column. EDTA (10(-4)M) in methanol-water mixture (78:22 v v ) was used as eluent at a flow-rate of 0.5 ml min .

Simple and rapid spectrophotometric determination of iron after preconcentration as its 1,10-phenanthroline complex on the natural polymer “chitin”

Preconcentration by collection of metal complexes on chitin has been applied to the spectrophotometric determination of iron in water. The iron is collected as its 1,10-phenanthroline (phen) complex on a column of chitin in the presence of tetraphenylborate as counter-ion. The iron(II)-phen complex retained on the chitin is eluted with an acetone-1M acetic acid mixture (8:2 v/v), and the absorbance of the eluate is measured at 512 nm. Beers law is obeyed over the concentration range 1.1-11.2 mug of iron in 10 ml of eluate. In the presence of EDTA as masking agent, Ca, Mg, Al, Mn, Zn, Cd and Pb do not interfere in concentrations up to 100 times that of iron(II) and Co, Ni and Cu do not interfere in concentrations up to 20 times that of iron(II). Common inorganic anions do not interfere in concentrations up to 10,000 times that of iron(II). The proposed method has been applied to determination of iron in tap water.

Synergistic Extraction of Lanthanides(III) with N‐p‐Methoxybenzoyl‐N‐Phenylhydroxylamine and Neutral Nitrogen Donors

Abstract We investigated the extraction equilibrium behavior of a series of trivalent lanthanide ions, (M3+), La, Pr, Eu, Ho, and Yb, from tartrate aqueous solutions using a chloroform solution containing N‐p‐methoxybenzoyl‐N‐phenylhydroxylamine (Methoxy‐BPHA or HL) combined with an adductant, 1,10‐phenanthroline (phen) or 2,2′‐bipyridyl (bipy). The synergistic species extracted were found to be {ML2(phen)(HL)}+(1/2)Tar2− and {ML2(bipy)(HL)2}+(1/2)Tar2−, where Tar2− is the tartrate ion. The stoichiometry, the extraction constants, and the separation factors of these systems were determined. We discuss the extractability and the separation factors in comparison with self‐adduct chelates, ML3(HL)2,(o), which were formed in the absence of phen or bipy.

Solvent Extraction of Lanthanides(III) with N‐p‐Phenylbenzoyl‐N‐phenylhydroxylamine

Abstract N‐p‐Phenylbenzoyl‐N‐phenylhydroxylamine (phenyl‐BPHA) was newly synthesized. The acid‐dissociation constant and distribution constant between chloroform and 0.1 mol dm−3 potassium chloride solution of phenyl‐BPHA were spectrophotometrically determined. The solvent extraction of lanthanides(III) (Ln) with phenyl‐BPHA was investigated. The representative lanthanides (Yb, Ho, Eu, Pr, and La) were all found to extract with compounds as self‐adducts of the form, LnL3(HL)2, where L and HL denote the ligand anion and neutral ligand, respectively. The extraction constant and separation factor were compared with those of the other derivatives of N‐benzoyl‐N phenylhydroxylamine (BPHA) previously reported. As the results, it was found that the separation factors for lanthanides(III) pairs represented by Pr/Eu, Eu/Yb, and Pr/Yb, with phenyl‐BPHA have moderate values by the comparison of those of other hydroxamic acids and other extractants.

Steric effect of substituents on the extraction of lanthanoids(III) with N-p-(n-, iso- and tert-)butylbenzoyl-N-phenylhydroxylamine.

N-p-(n-, iso- and tert-)Butylbenzoyl-N-phenylhydroxylamine (HL) was synthesized to evaluate the steric effect of the substituent on the mutual extraction separation of representative lanthanoids(III) (Ln). Lanthanoids(III) were all found to be extracted with compounds as self-adducts of the form LnL(3)(HL)(2). It was found that the structure of the substituents in N-p-butylbenzoyl-substituted N-phenylhydroxylamine is closely related to the separation factor for the pair of Yb/Eu. The separation factors for a pair of Eu/Yb with these compounds decreased in the order of tert-butyl derivative>iso->n-, with a decreasing Tafts E(s) value, that is, with an increasing steric effect of the substituent group. The correlation between the separation factor and the stereochemical shape of the substituent was also investigated.

SOLVENT EXTRACTION OF LANTHANIDES WITH N-m-AND N-p-METHOXYBENZOYL-N-PHENYLHYDROXYLAMINE

ABSTRACT The solvent extraction of lanthanides with N-o-methoxy-(o-MBPHA), N-m-methoxy- (m-MBPHA) and N-p-methoxybenzoyl-N-phenylhydroxylamine (p-MBPHA), respectively, in chloroform was studied. The selected lanthanides (Yb, Ho, Eu, Pr and La) were all found extract with m- and p-MBPHA as self-adducts of the form LnL-2HL, where L and HL denote the ligand anion and neutral ligand, respectively. The extraction constant and separation factors for the lanthanides with m- and p-MBPHA were evaluated.

Extraction-spectrophotometric determination of vanadium with N-m-tolyl-N-phenylhydroxylamine and its application to coal and coal fly-ash

N-m-Tolyl-N-phenylhydroxylamine is proposed for the spectrophotometric determination of small amounts of vanadium. The reddish-violet complex formed with the reagent in 3-6M hydrochloric acid after extraction with chloroform shows an absorption maximum at 530 nm, and obeys Beers law for 0-76.5 mug of vanadium in 10 ml of chloroform. The proposed method has been successfully applied to the determination of vanadium in coal and coal fly-ash.

DISTRIBUTION EQUILIBRIUM OF LANTHANIDE(III) COMPLEXES WITH N-BENZOYL-N-PHENYLHYDROXYLAMINE IN SEVERAL INERT SOLVENT SYSTEMS

ABSTRACT The distribution equilibrium of lanthanides(III) (Ln) with N-benzoyl-N-phenylhydroxylamine (BPHA, HL) in several inert solvent systems was studied. The representative lanthanides(III) (Yb, Eu and Pr) were all found to extract as self-adduct chelates of the form, LnL3(HL)m, (m = 1–3), containing a different number of neutral adduct molecules in extracted species. The differences in the number of neutral adduct molecules in extracted species with each solvents are attributed to the difference in the solvation trend for BPHA. The extraction constant and separation factor were determined in several inert solvent systems. It was found that the distribution ratio of lanthanide(III) tends to decrease with increases in the distribution constant of BPHA. Relationship between the polarity of the solvent and the extractability are also discussed.

Separation of trans-1,2-cyclohexanediaminetetra-acetic acid chelates of bismuth(III), iron(III) and copper(II) by reversed-phase paired-ion chromatography

Trans-1,2-cyclohexanediaminetetra-acetic acid (DCTA) chelates of bismuth(III), iron(III) and copper(II) have been separated by two techniques using reversed-phase paired-ion chromatography. In one, the chelates in aqueous solution were separated within 20 min on a 6.0 x 300 mm ERC-ODS column with 10(-2)M tetrabutylammonium ion (TBA(+)) in methanoi-water mixture (45:55 v v ) as eluent. In the other, the metal ions in aqueous solution were separated within 10 min by direct injection into an ERC-ODS column with 10(-2)M TBA(+)/10(-3)M DCTA in methanoi-water mixture (40:60 v v ) as eluent.

Synergistic Extraction of Lanthanides(III) by Mixtures of N‐p‐Methoxybenzoyl‐N‐phenylhydroxylamine and 1,10‐Phenanthroline

Abstract We conducted a study on the equilibrium extraction behavior of the trivalent lanthanide ions (M3+), La, Pr, Eu, Ho, and Yb, from tartrate aqueous solutions into chloroform solutions containing N‐p‐methoxybenzoyl‐N‐phenylhydroxylamine (Methoxy‐BPHA, HL) and 1,10‐phenanthroline (phen). The synergistic species extracted was found to be {ML2(phen) (HL)}+(1/2)Tar2−, where Tar2− is tartrate ion. The extraction constants were calculated. The extraction separation behavior and extractability of lanthanides are discussed in comparison with the self‐adducted chelate, ML3(HL)2, which was extracted in the absence of phen, and synergistic extraction by mixtures of other extractants such as 2‐thenoyltrifluoroacetone, and neutral donors.