The bis(trifluoromethanesulfonato)nickel(II) complex with two 2, 2′-bipyridine (bpy), [Ni(bpy)₂(CF₃SO₃)₂] (1), and the mono(trifluoromethanesulfonato)palladium(II) complex with bis(2-diphenylphosphinoethyl)phenylphosphine (p₃), [Pd(p₃)(CF₃SO₃)](CF₃SO₃)•C₆H₆ (2), were isolated. The crystal structures for 1 and 2 have been determined by an X-ray crystal structure analysis. Complex 1 crystallizes in monoclinic space group Aa with a=18.55(1), b=14.48(1), c=9.941(7)Å, β=101.98(3)°, and Z=4. Complex 2 crystallizes in the monoclinic space group P2₁/n with a=17.211(5), b=27.175(7), c=9.962(2)Å, β=105.66(2)°, and Z=4. The crystal of 1 contains a distorted octahedral nickel(II) complex with a cis arrangement, and the crystal of 2 contains a distorted square-planar palladium(II) complex. The metal-oxygen bond distances for triflate (CF₃SO₃^-), (2.135(5) and 2.148(4)Å for 1 and 2.126(7)Å for 2), are comparable to those for the other oxygen donors. Three S-O bond distances in the coordinated triflate are close to one another. The stability of the metal-oxygen bond is discussed in terms of the electronic property of triflate.

View full abstract

(R, S)-N-(3, 5-dinitrophenyl)-α-methylbenzeneacetamide [(R, S)-PPA-DNA] can be resolved into its enantiomer on the chiral stationary phase (CSP) which chemically bonded with (S)-α-methyl-1-naphthylamine. To investigate the mechanism of this chiral discrimination in liquid chromatography, an X-ray crystallographic study of two diastereomeric equimolar complexes was performed. (S)-N Acetyl-α-methyl-1-naphthylamine [(S)-NEA-a] and (R), (S)-PPA-DNA were used as models of the CSP and the analyte, respectively. The crystal structures of both diastereomeric complexes were clarified so that the hydrogen bond and the π-π donor-acceptor intermolecular interaction dominated the chiral discrimination, suggesting that the chiral discrimination was caused by the differences in the binding force and in the number of intermolecular interactions within a combination of the CSP model and the analyte in suitable association. This interpretation of the result of X-ray crystallography agreed with the elution order on chromatography. The correlation between the crystal structure and the proton nuclear magnetic resonance (NMR) spectroscopy is also discussed.

View full abstract

4, 5-Diaminophthalhydrazide is shown to be a highly sensitive chemiluminescence derivatization reagent for aldehydes, especially for aromatic aldehydes, in high-performance liquid chromatography (HPLC). The reagent reacts selectively with aldehydes in acidic media to give highly chemiluminescent benzimidazol derivatives which produce chemiluminescence by reaction with hydrogen peroxide and potassium hexacyanoferrate(III). The derivatives in the reaction mixture of four aldehydes are separated by reversed-phase HPLC with isocratic elution, followed by chemiluminescence detection. For a 20-μl injection volume, the detection limits (S/N=3) for aromatic and aliphatic aldehydes are in the ranges 1-150fmol and 0.05-2.8pmol, respectively.

View full abstract

Catecholamines have been measured using a fully-automated HPLC-ethylenediamine condensation reaction-peroxyoxalate chemiluminescence (CL) detection system with both high sensitivity and selectivity. When a CL solution containing trifluoroacetic acid was kept at room temperature, 4°C or -20°C, and then used for the CL detection of catecholamines, the CL intensity was significantly increased. With the solutions stored at -20°C, the maximum CL intensity was observed, even after being stored for one year. This increase in the CL intensity was observed with CL solutions prepared using either bis(2, 4, 6-trichlorophenyl)oxalate (TCPO) or bis[4-nitro-2-(3, 6, 9-trioxadecyloxycarbonyl)phenyl]oxalate (TDPO) in either dioxane/ethyl acetate or acetonitrile. A certain strong carboxylic acid in the CL solution, such as trifluoroacetic acid, trichoroacetic acid or heptafluorobutyric acid, was necessary in order to increase the CL intensity. This increase in the CL intensity was also observed even after decomposition of all the oxalate in the CL solution, suggesting that an active intermediate(s) for generating CL is produced in a strongly acidic solution during storage.

View full abstract

Chemiluminescence (CL) was observed during the peroxidation of homogentisic acid γ-lactone catalyzed by horseradish peroxidase (HRP) in an aqueous dimethyl sulfoxide (20%v/v) solution. The intensity of light emission was linearly correlated with the HRP concentration over the range from the detection limit of 1fmol to 30pmol. The CL reaction was applied to the detection of HRP-labeled antigen in an enzyme immunoassay of taurocholic acid. Taurocholic acid was determined in the range from 10pg to 100ng. The detection limit with the present method was 25-times lower than that with a colorimetric method.

View full abstract

A laser-induced fluorescence detection system for capillary electrophoresis using a visible semiconductor laser and an avalanche photodiode has been developed. These solid-state devices offer both reliability and compactness for instrumental design. A time-resolved photon-counting method with a subnanosecond resolution has reduced the large dark counts of the avalanche photodiode and the contribution from scattered light. The baseline fluctuation of the electropherogram is due to the shot noise of the avalanche photodiode. The detection limit (S/N=2) for a model dye compound, Oxazine 725, is 2.1fmol as an injection amount. This value is comparable to that of the conventional laser fluorometry system with a gas laser and a photomultiplier.

View full abstract

λ phage DNA on nitrocellulose filters was quantified by a fluorometric assay using a biotin-labeled DNA probe and a p-acetamidophenol analog that yield a fluorescent product by enzymatic oxidation. Biotinylated λ phage DNA (Hind III digested), used as a DNA probe, was prepared by diazobiotin, which reacts at the phosphate moiety of DNA. Peroxidase-labeled avidin was bound to biotin-labeled DNA, which was hybridized with λ DNA on a nitrocellulose filter. The DNA was detected using a fluorogenic substrate for peroxidase, 4-(4-hydroxyphenylcarbamoyl)butanoic acid (HPBA) in the presence of hydrogen peroxide. The assay permits the determination of λ phage DNA as low as 0.1pg by a flow-through system.

View full abstract

An assay procedure utilizing pulsed amperometric detection at a platinum-particles modified electrode has been developed for the determination of cysteine and glutathione in blood samples following preliminary separation by reversed-phase liquid chromatography. A chemically modified electrode (CME) constructed by unique electroreduction from a platinum-salt solution to produce dispersed Pt particles on a glassy carbon surface was demonstrated to catalyze the electo-oxidation of sulfhydryl-containing compounds: DL-cysteine (CYS), reduced glutathione (GSH). When used as the sensing electrode in flow-system pulsed-amperometric detection (PAD), electrode fouling could be avoided using a waveform in which the cathodic reactivation process occurred at a potential of -1.0V vs. Ag/AgCl to achieve a cathodic desorption of atomic sulfur. A superior detection limit for these free thiols was obtained at a Pt particle-based GC electrode compared with other methods; this novel dispersed Pt particles CME exhibited high electrocatalytic stability and activity when it was employed as an electrochemical detector in FIA and HPLC for the determination of those organosulfur compounds.

View full abstract

The simultaneous determination of D-glucose and 3-hydroxybutyrate in a plasma and serum by a split-stream flow-injection method using two immobilized enzyme reactors is described. One reactor for the determination of D-glucose was packed with glucose dehydrogenase and NADH oxidase co-immobilized on poly(vinyl alcohol) beads; the other reactor for 3-hydroxybutyrate was packed with 3-hydroxybutyrate dehydrogenase and NADH oxidase co-immobilized on the beads. The hydrogen peroxide produced by the enzymatic reactions was detected by measuring the chemiluminescence emitted upon admixing with luminol and potassium hexacyanoferrate(III). For 3-hydroxybutyrate the calibration graph was linear over the range 1×10^-6-5×10^-4M; for D-glucose it was 1×10^-5-1×10^-3M. One assay could be completed within 6min with satisfactory precision (<2.9% relative standard deviation).

View full abstract

To 1.5g of γ-alumina particles in40ml of water was added 10ml of ammoniacal solution containing 1.5mg of dithizone and 100mg of sodium dodecyl sulfate. The solution was acidified to pH 2 to form the surfactant aggregates on the alumina surfaces, into which dithizone was trapped. Traces of copper(II) and silver(I) in water were completely collected on the dithizone-coated alumina over a wide range of pH 1-7; cadmium(II), cobalt(II), nickel(II), lead(II) and zinc(II) were simultaneously recovered at pH 3-7. The chelating sorbent functioned well even in aqueous solutions containing a large amount of matrix element. The proposed sorption method has been successfully applied to the determination of traces of copper in lead metal.

View full abstract

_L-Ascorbic acid, sulfite, sulfide and thiosulfate have each been completely separated from their mixtures by a single run of ion chromatography using columns of a sulfonated styrenedivinylbenzene copolymeric cation-exchange resin of low crosslinking (1%) and an eluent of 2.3×10^-3M (M=mol dm^-3) sulfuric acid containing 4%(v/v) acetonitrile. L-Ascorbic acid and sulfite as sulfurous acid were eluted early by an ion-exclusion effect of the cation-exchanger in the hydrogen form, but both the sulfide as hydrogen sulfide and the thiosulfate ion were eluted late, owing to their adsorption onto the resin bed. The sample species in the effluent were monitored by photometric measurement of the excess of iodine (as triiodide) for its postcolumn reaction with each species separated. The chromatograms obtained gave negative peaks, based on the decrease in the absorbance from background. Calibration graphs for the four species, plotted as peak-heights vs. concentrations, were linear up to 3.00×10^-5M for _L-ascorbic acid, 1.25×10^-4M for sulfite, 5.00×10^-4M for sulfide and 1.20×10^-4M for thiosulfate, respectively. Detection limits as S/N=3 were 1.00×10^-7M for L-ascorbic acid, 1.15×10^-6M for sulfite, 1.80×10^-6M for sulfide and 6.80×10^-6M for thiosulfate. The proposed method was successfully applied to the determination of L-ascorbic acid in soft drinks, sulfide in hot-spring waters and sulfite in wines.

View full abstract

The carrier-mediated transport of europium through a supported liquid membrane by immobilizing PC-88A (EHPNA) and Versatic 10 on a porous support has been investigated in order to explore its efficiency, effectiveness and utility. Europium from the source solution was transported in the pH range from 1 to 5.75 for EHPNA and 3 to 5.75 for Versatic 10 through a cellulose triacetate membrane towards a receiving solution of pH<2. However, the change in the europium concentration in the source solution with respect to time (t) was observed based on the expression. The observed permeability coefficient (P) increased along with an increase in the carrier concentration for both the EHPNA and Versatic 10 systems in the concentration ranges studied, 1.8×10^-5 to 1.8×10^-2M (mol dm^-3) and 1.8×10^-5 to 4×10^-2M respectively. Above this range it remained nearly constant. The effect of complexation with citric, succinic and malonic acids on the permeability has been explored. The enrichment factor (EF) has also been evaluated.

View full abstract

The proton nmr spectra for six compounds: 6-ethyldibenzo[b, i]-1, 4, 8, 11-tetraazacyclotetradeca-4, 6-diene (1), dibenzo[b, i]- 1, 4, 8, 11-tetraazacyclotetradecane, 1, 3-bis(2-aminophenylamino)propane, 1, 4, 8, 11-tetraazacyclotetradecane (cyclam), N-ethylaniline and diethylamine, were measured in twelve solvents. Every proton signal is shifted to higher fields in toluene-d₈ and benzene-d₆ than in cyclohexane-d₁₂ solution. On the other hand, the proton signals for the secondary amines are shifted to low fields in polar solvents. Proton signals for methylene and/or methyl groups are not shifted. The amine signal for 1(arom.) shows a small shift in every solvent. There is no appreciable interaction between the amine proton and solvent because the amine proton is in the inner space of 1. The amine signals, except for 1(arom.), have an increasing down-field shift in the following order: toluene-d₈, benzene-d₆, cyclohexane-d₁₂, dichloromethane-d₂, chloroform-d, nitromethane-d₃, acetonitrile-d₃, acetone-d₆, tetrahydrofuran-d₈, N, N-dimethylformamide-d₇, dimethyl sulfoxide-d₆, pyridine-d₅. These results and solvent effects are discussed.

View full abstract

Two kinds of acidic organophosphonates with different bulky ester groups, 2-[p-(1, 1, 3, 3-tetramethylbutyl)phenoxy]ethyl And p-(1, 1, 3, 3-tetramethylbutyl)phenyl groups, were synthesized to investigate their extraction behavior for nine kinds of rare earth elements from aqueous acidic nitrate media. The extraction reaction was discussed based on the slope analysis to evaluate the extraction equilibrium constants (K_ex) for each metal ion and the separation factors (β). These extractants synthesized in the present work were found to possess stronger extractabilities for rare earth metals than commercial extractants like D2EHPA and PC-88A. Their separation efficiencies are also comparable with the commercial extractants mentioned above.

View full abstract

The solvent extraction of ion associates of tetrahalogenoaurate(III) ions, AuX₄^-(X^-=chloride or bromide), with quaternary ammonium cations (Q⁺) has been studied. The extraction constants (K_ex) were determined for the ion associates of AuX₄^- with Q⁺ between an aqueous phase and several organic phases (chloroform (CF), chlorobenzene (Cl-B), benzene (B), toluene (T) and carbon tetrachloride (CTC)). The extractability of AuX₄^- was in the order AuBr₄^- >AuCl₄^-; the difference in logK_ex between tetrachloroaurate(III) and tetrabromoaurate(III) was about 1.16 on the average. Among the ion associates examined, the extractability of the extracting solvent was generally in the order CF>Cl-B>B>T>CTC; the differences in logK_ex between two successive solvents in this order were about 0.26, 0.40, 0.09 and 0.10 on the average. The contribution of a methylene group in Q⁺ to logK_ex was about 0.5 on the average. From the obtained extraction constants, possible extraction systems for the spectrophotometry of gold are predicted: tetrabutylammonium cation•AuCl₄^--chloroform, tetraamylammonium cation•AuCl₄^--chloroform, tetra-butylammonium cation•AuBr₄^-chloroform, tetrabutylammonium cation•AuBr₄^--chlorobenzene and tetraamylammonium cation•AuCl₄^--benzene.

View full abstract

Magnesium can be determined at levels above 1% in poly (vinyl chloride) (PVC) by direct analysis of the solid sample using graphite furnace atomic absorption spectrometry (GFAAS) and working at the 383.4nm line. The analytical conditions used permit the determination of magnesium at a concentration of 2% by interpolation on a calibration graph run for the aqueous solution. No special sample introduction system, platform or matrix modification is required. The relative standard deviation thus achieved is ca. 7%.

View full abstract

In order to determine the contents of phosphorus and sulfur rapidly in the iron-making process, a new determination system has been developed. This system is characterized by the rapid extraction of phosphorus and sulfur from a solid sample by the wet chemical reaction, and simple detection using a paper-tape detector. Hydrochloric acid is sprayed onto the surface of an iron sample, and about 5mg of the sample is dissolved. Phosphorus and sulfur in the sample are extracted as phosphine and hydrogen sulfide, respectively, during the supply of hydrochloric acid. These gases are transferred to a paper-tape detector with an inert-gas carrier. In the detector, phosphine and hydrogen sulfide are reacted with silver nitrate and lead acetate, respectively, on the paper tapes; the resulting stain is measured by reflectance photometry. As the result of analyzing pig iron, ranges of 0.01-0.1% phosphorus and 0.003-0.03% sulfur are determined simultaneously with relative standard deviations of 15% or less. The time required to analyze one sample is less than 2min. This system is expected to be used at production sites of the iron-making process.

View full abstract