The paper discusses the anomalies of the former interpretation of the working mechanism of ion-selective electrodes. It was thoroughly discussed why the Donnan experiment could not be applied as the theoretical background of glass electrodes. It was assumed according to the Donnan interpretation that the measurable potential is produced by the transfer of the primary ion through the membrane. Since the 1960s, the author and coworkers have been investigating the problem of what can be the reason for the potential response of the electrodes. Practical measurements in connection with the response time, surface hindered reactions etc. were interpreted. Furthermore, the energy problems according to the Gibbs theory using two electrode components were investigated. It was established that the electrodes on which chemical reactions may occur with the primary ion have a surface reaction as the chemical basis of the response. For electrodes that work on the principle of the lyotropic series, surface reactions are also involved, but their response is not always Nernstian. The energy demand is covered by the charge separation at the electrode-solution interface.

View full abstract

A new field of Analytical Chemistry, Bio-Analytical Chemistry, is proposed. It would treat the analysis of biomolecules related to the maintenance of homeostasis in living mammals, the analysis of biomolecules or chemicals of unknown as well as known physiological roles and also would include the development of methods to search into and clarify the mysteries in nature. Some examples of our studies performed in the line of this field are presented. The proposal is made in order to stimulate more young people to participate in and be involved in the promotion of Analytical Chemistry.

View full abstract

A new electroanalytical method for detecting methylamphetamine as a stimulant drug in human urine has been proposed for forensic purposes. Although methylamphetamine itself has no remarkable voltammetric waves at any electrode in various electrolytes, we have found that the copper complex of methylamphetamine obtained by the method of Feigl showed a well-defined peak at -0.56 V (vs. SCE) at a mercury electrode by differential pulse polarography (DPP) in an aqueous ethanol solution containing 0.25 M ammonium acetate. The peak height was linear as a function of the methyl-amphetamine concentration in the original test solutions in the region of at least 0 - 50 µg/ml. The concentrations of methylamphetamine determined by the present method for eight abusers’ urine samples were in excellent agreement with those obtained by the conventional methods (GC-MS analysis) so far used. The proposed method is rather simple in procedure, rapid and selective with a satisfactory detection limit (<0.125 µg/ml) for analysis of methylamphetamine, and would also be applicable for field use.

View full abstract

Black, blue and red writing pens were classified into various groups using the R_f values and color tones of dyestuff bands separated by normal-phase thin-layer chromatography (TLC) of their inks. The classification is effective for the preliminary identification of pens used in crime scenes. A microsampling technique was proposed for the TLC analysis of minute quantities of inks on questioned documents. Furthermore, a combination of reflectance-mode microscope/Fourier transform infrared spectroscopy and the pin-point condensation technique was proved to be useful for the precise discrim-ination of trace amounts of analogous water-soluble dyestuffs on TLC plates.

View full abstract

Total reflection X-ray fluorescence spectrometry (TXRF) is one of the most common tools to analyze metal contaminants on silicon wafers and other substrate surfaces. Although the detection limit of commercial TXRF was improved to the concentration region of 10⁹ atoms cm^-2, its accuracy at low concentration was not yet clarified until now. In this paper, we examine the accuracy of the quantitative analysis by TXRF under 10¹¹ atoms cm^-2 for Fe, Ni, Cu and Zn. In particular, four factors (standard sample, reference analyzing method, compensation of spurious peak and peak separation) are considered. Under a controlled condition, the accuracy is within 20% as compared with atomic absorption spectropho-tometry (AAS).

View full abstract

A quantification method in secondary ion mass spectrometry called the “high-energy method” is proposed: it uses the exponential dependence of secondary ion intensities on the reciprocal of ion velocity. This method was derived from the same velocity dependence of secondary-ion emission as the infinite velocity method proposed by van der Heide, but does not require either the entire energy spectrum of each secondary ion or the special inverse velocity plot. The high-energy method is suitable for simple evaluation of concentrations ranging from several parts per million to tenths of percents.

View full abstract

Sodium ions can be used as efficient chemical ionization agents in electrospray mass spectrometry of a wide variety of neutral metal bipyridine complexes. This ionization method was successfully permitted the identification of a neutral metal complex generated during the photochemical ligand substitution reaction: [Re(bpy)(CO)₃{P(OEt)₃}]⁺+Cl^- → Re(bpy)(CO)₂{P(OEt)₃}Cl+CO by sodium adduct formation to produce an electrospray-active species [Re(bpy)(CO)₂{P(OEt)₃}Cl+Na]⁺.

View full abstract

It is proved that both “electrochemical” and “chemical” treatments of the equilibrium distribution of electrolytes between two polar solvents are correct, or in other words the use of electrochemical or chemical potentials is interchangeable. This is illustrated by calculation using a recursive iteration program for distribution of Sr²⁺ by dicarbollide anion in the presence of polyethyleneglycol. Several particular situations are described: the effect of common ion, limiting distribution coefficient and influence of protonized particles on distribution of cations.

View full abstract

The extraction of arsenic(III) was investigated by using macroporous resin impregnated with a newly synthesized hydrophobic extractant: bis(2-ethylhexyl)ammonium bis(2-ethylhexyl)dithiocarbamate (BBDC). In a preliminary experiment on liquid-liquid extraction, arsenic(III) was favorably extracted with BBDC in heptane from acidic to neutral solutions; the distribution ratios with 0.01 mol dm^-3 BBDC were larger than 10^2.5 at pH 0 - 6. The batchwise extraction of arsenic(III) with the impregnated resin was carried out. The distribution ratio was more than 10³ in an acidic region, and sharply decreased above pH 8. The collection of a trace amount of arsenic(III) was performed by using the column packed with the impregnated resin as a stationary phase. Then arsenic(III) retained on the column was quantitatively eluted out with an alkaline solution.

View full abstract

The metal complex stability between tervalent rare earth metal ions (ytterium, praseodymium, europium, gadolinium, holmium and ytterbium) and 1,10-diaza-4,7,13,16-tetraoxacyclooctadecane (kryptofix 22) in aqueous sodium chloride solution was studied by solvent extraction method. The solvent extraction included 2-thenoyltrifluoroacetone as a chelating extractant and carbon tetrachloride as a solvent. The metal extractability in the absence and presence of kryptofix 22 gave a quantitative measure of the stability of metal-kryptofix 22 complexes formed in aqueous solution which were found to be unanimously 1:1 (metal:ligand ratio) in composition. The complex stability constants thus obtained (0.1 M sodium chloride, 298 K) were in the range 10⁹ - 10¹¹, being maximum at gadolinium. The values were discussed in com-parison with those of the related ligand 18-crown-6.

View full abstract

The ion-association properties of monovalent and divalent naphtholsulfonate ions were investigated with tetrabutylammonium ion (TBA⁺) as a pairing ion in an aqueous solution. The ion-association constants were obtained by analyzing the change in the electrophoretic mobility of naphtholsulfonate ions in the presence of TBA⁺ by capillary zone electrophoresis; also, the contribution of a hydroxyl group to the ion associability of monovalent and divalent naphtholsulfonate ions, as well as the electrophoretic mobility of the ions, was investigated. The obtained ion-association constants indicate that the positional isomers possessing anionic groups at the β-position of the naphthalene ring are more associable with TBA⁺ than those at the α-position, and that the ion associability of the divalent naphtholsulfonates is larger than those of the monovalent ones, except for 1-naphthol-2-sulfonate. The abnormal associability of 1-naphthol-2-sulfonate can be explained by a synergistic increase in the hydrophilicity of the divalent ion. The difference in the ion associability between the monovalent and divalent naphtholsulfonates, 0.16 in log unit on the average, was smaller than that between the naphthalenesulfonate and naphthalenedisulfonate ions, 0.30 log unit on the average. The electrophoretic mobility of the naphtholsulfonate ions obtained in the absence of TBA⁺ is compared with each other, and the contribution of the hydroxyl group is discussed on the basis of the hydration behavior of the naphtholsulfonates.

View full abstract

A simple and reliable concentration method of trace metals in aqueous solution is proposed. 2-(5-Bromo-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino)phenol is used to form water-soluble metal chelates. The chelated metal ions are concentrated from dilute solution by adsorption onto a C₁₈-bonded silica gel column. The adsorbed chelates are eluted with methanol and 1.0 mol dm^-3 HCl and determined by ICP-AES or flame AAS. The proposed method is applied to the determination of heavy metal impurities in some commercial sodium salt reagents.

View full abstract

A thermal method for the fractional determination of elemental carbon (EC) and total soluble and insoluble organic compounds (TSOC and TIOC) in airborne particulate matter has been developed by the optimization of its heating schedule and the pre-separation of other thermal degradable matter. Mixtures of cotton, sucrose or starch as model insoluble organic compounds and carbon black or activated carbon as model EC were subjected to thermogravimetry-differential scanning calorimetry (TG-DSC), and its heating schedule was investigated to separate an exothermic peak of carbon generated from organic compounds from that of EC. The heating schedule with a holding step at 430°C for 60 min gave the best recoveries for such carbonaceous components. Weight losses of 180 - 485°C and 485 - 665°C in TG curves were adopted for the determination of TIOC and EC, respectively. In order to determine TSOC and to separate thermal degradable inorganic compounds like sulfate, carbonate and hydroxide, systematic separation consisting of acetone, water and 0.1 M hydrochloric acid extraction and heavy liquid separation of its residue was applied to real samples prior to ther-mal analysis. The fractions were subjected to TG-DSC; EC and TIOC were successfully determined fractionally.

View full abstract

Humic and fulvic acids in environmental water were determined by UV spectrophotometry after concentration with diethylaminoethyl(DEAE)-cellulose and separation at pH 1 by centrifugation. The ranges of fulvic and humic acids in Katsura, Uji, Kidzu and Yodo Rivers were from about 0.50 to 3.2 mg/l and 0.025 to 0.2 mg/l, except for the sampling points, which were located downstream of a sewage-disposal plant. Fulvic acid was predominant in these rivers. The concentrations of humic substances were high in the summer and low in the winter. The concentrations of humic substances in these rivers decreased fairly much from December of 1992 to August of 1993. The annual changes in the values of humic substances during 1993 to 1996 were smaller than the change from 1992 to 1993. The trends for the seasonal and annual changes in the concentration of the trihalomethane formation potential in Yodo rivers were almost consistent with those of humic substances.

View full abstract

A sensitive method based on preconcentration on a membrane filter with a finely pulverized anion-exchange resin has been developed for the determination of iron(II) in water samples by photoacoustic spectrometry. Iron(II) reacts with 2-nitroso-5-(N-propyl-N-sulfopropylamino)phenol (Nitroso-PSAP) to form a water-soluble chelate anion, which is adsorbed on the resin at pH 8.0; the resulting resin is filtered through a membrane filter (13 mm in diameter). The resin with the membrane filter is inserted into a cell, and the intensity of the photoacoustic signal of iron(II) is measured at 826 nm. The calibration graph for iron(II) was linear over the range 0.05 - 0.8 µg in 30 - 500 ml of a sample solution. The relative standard deviation for eight measurements at 0.5 µg of iron(II) was 5.4%. The detection limit was 10 ng of iron(II) in 500 ml (20 ngFe l^-1). The interference of various ions was studied and the optimum conditions were developed for the deter-mination of iron(II) in mine-drainage and river-water samples.

View full abstract

A sensitive and selective method for the determination of trace amounts of cobalt(II) is described. The method is based on the combined use of 1-(2-pyridylazo)-2-naphthol (PAN) and 2-(5-bromo-2-pyridylazo)-5-[N-propyl-N-(3-sulfo-propyl)amino]phenol (5-Br-PAPS). Cobalt(II) is first extracted on a membrane filter as the cobalt(III)-PAN complex and the complex is decomposed with acid. The cobalt is then extracted on a membrane filter as the cobalt(III)-5-Br-PAPS complex in the presence of dodecylbenzenesulfonate and determined by densitometry. The proposed method has been applied to the determination of cobalt in tap water and beverages.

View full abstract

2-(5-Bromo-2-pyridylazo)-5-[N-propyl-N-(3-sulfopropyl)amino]phenol (5-Br-PAPS) was used as a precolumn chelating agent for the determination of cobalt in natural water. Co(III)-5-Br-PAPS chelate was preconcentrated with the concentration column (50 mm×4.6 mm i.d.) packed with C18-silica gel sorbent by mean of a column-switching technique. The preconcentrated Co(III) chelate was flushed with the mobile phase by manual action of a switching valve. Then, it was separated by the reversed-phase analytical column. The thermodynamically stable and kinetically inert Co(III) chelate was detected without decomposition using the eluent containing no chelating agent. One cubic centimeter of injection enabled detection of 4.0×10^-11 mol dm^-3 of Co(II) with on-line preconcentration. The method was applied to natural waters.

View full abstract

Poly(acrylonitrile) with a terminal reactive group at one side of the main chain was prepared by telomerization of acrylo-nitrile with 3-mercaptopropyltrimethoxysilane and then immobilized onto porous silica. HPLC using the packed column (Sil-AN_n) and an aqueous solution as a mobile phase showed several unique retention behaviors for hydrocarbons: (1) the retention factor for alkylbenzenes was almost independent of the alkyl length although simply cyanopropylated silica (Sil-CN) showed the increase of the retention time with increase of the alkyl length. (2) Sil-AN_n showed remarkably better selectivity for π-electron containing hydrocarbons compared with Sil-CN and hydrophobized silica. In this paper, such specificity of Sil-AN_n is discussed in relation to π-electron recognition ability of poly(acrylonitrile) moiety.

View full abstract

The retention behavior of p-alkylphenols was studied in reversed-phase liquid chromatography using octadecylsilyl-silica gel and ethanol/water mobile phases. The results were compared with those in methanol/water systems. Linear correlations were observed between the logarithmic retention factor (ln k) and the carbon number of side chains in the solutes, irrespective of the type and volumetric fraction (φ) of the organic modifiers in the mobile phases. The straight lines mea-sured at different φ converged at almost one point. By analyzing the slope of the linear correlations, a functional contribution of a methylene group to k and a reduction of the hydrophobic surface area of the solutes and octadecylsilyl ligands due to the retention were estimated. It was also attempted to analyze the characteristics of the retention in reversed-phase liquid chromatography on the basis of solvophobic theory.

View full abstract

The mass-transfer characteristics were studied in a reversed-phase liquid chromatography consisting of an octadecylsilyl-silica gel and acetonitrile/water mixture (70/30, vol), and were compared with those obtained by using methanol/water (70/30, vol). In the two chromatographic systems, similar tendencies were observed for various adsorption characteristics. However, their absolute values were not entirely identical. Irrespective of the type of organic modifiers, surface diffusion was dominant for intraparticle diffusion. Similar correlations were also demonstrated with regard to the surface diffusion, i.e., the enthalpy-entropy compensation and the linear free-energy relation, suggesing a similarity in the surface migration mechanism in the two chromatographic systems. A few estimation procedures of the surface diffusion coefficient were proposed.

View full abstract

A simple and sensitive method was developed for the capillary electrophoretic determination of Cr(VI) and Cr(III). In a 0.1 M CClH₂COOH-CClH₂COONa buffer of pH 2 - 3, Mo(VI) reacts rapidly, even at room temperature with Cr(III), to form a stable heteropolyanion. Both anionic forms of Cr(III) and Cr(VI) can be determined simultaneously by capillary electrophoresis with UV detection at 256 nm. Linear calibration curves were obtained in the concentration ranges of 5×10^-6 - 1×10^-4 M and 1×10^-5 - 1×10^-4 M for Cr(III) and Cr(VI), respectively; the detection limits were 2×10^-6 and 5×10^-6 M (the signal-to-noise ratio=5). Interference from foreign ions is also discussed.

View full abstract

Monosaccharides were investigated as chiral selectors in capillary electrophoresis of binaphthyl compounds. Among monosaccharides tested, glucose, mannose and their derivatives, except for methyl-β-D-glucopyranoside, were found to be effective for direct separation of racemic mixture of 1,1′-binaphthyl-2,2′-diyl hydrogenphosphate (BNP). D-Forms of galactose, sorbose, fructose, ribose, arabinose and xylose failed chiral separation of BNP. We tentatively concluded that monosaccharides (in the case of D-forms) must satisfy the following structural requirements for successful chiral separation of BNP enantiomers: (1) oxygen atom at C-1 is in α-configuration, (2) -OH group at C-4 is downward configurated and (3) the presence of a -CH₂OH or -CH₃ group at C-5. Thus, in the case of D-glucose, the chiral separation of BNP is anticipated to be achieved predominantly through the hydrogen bonding between oxygen atom at C-1 and hydrogen atom of -OH group at C-4 on D-glucose and hydrogenphosphate moiety of BNP.

View full abstract

A method for the determination of the critical micelle concentration (CMC) of anionic surfactants by capillary electrophoresis (CE) has been developed. The method is based on the measurement of migration time of 2-naphthalene-methanol as a marker compound in CE, using varying concentrations of a desired surfactant in phosphate buffer (pH 7.0) as electrolyte solution. When the migration time of 2-naphthalenemethanol was plotted against the surfactant concentration, an inflection point appeared which corresponded to the CMC. By the CE method, the CMC values of seven anionic surfactants including sodium salts of alkyl sulfate, alkylsulfonic acid, fatty acid and bile acid were successfully determined; the CMC of sodium dodecyl sulfate determined by the CE method was 3.92 mM, which agreed closely with those measured by a dye solubilization method (3.53 mM) and a conductometric method (4.02 mM). The present CE method enabled the determination of CMC, if required, using as little as 300 µl or smaller volumes each of varying concentrations of surfactant solutions.

View full abstract

On-line capillary electrophoresis-ionspray-mass spectrometry (CE-ISP-MS) was applied to a composition analysis of charged cyclodextrin (CD) derivatives. Quaternary ammonium β-CD (QA-β-CD) and carboxymethylated γ-CD (CM-γ-CD), which were used as chiral selectors for enantiomer separations by CE, were analyzed. As for QA-β-CD, eight components having different degrees of the quaternary ammonium substitution could be identified based on their mass spectra. The components were detected as either molecular ions or fragment ions. On the other hand, six components of CM-γ-CD were detected as bivalent molecular ions. Such composition analyses were difficult using CE with only the UV detector. CE-MS was found to be a promising technique for a composition analysis of mixed compounds.

View full abstract

The chemical composition of the high-level radioactive waste glass which was produced in the Windscale Vitrification Plant at Sellafield was determined by ICP-AES. The chemical analysis was performed in shielded cells and glove boxes at the Japan Atomic Energy Research Institute. The sample was dissolved by alkaline fusion with sodium peroxide and acidic decomposition with hydrofluoric and perchloric acids for determining Si and B, and Li, Na, Mg, Al, P, Cr, Fe, Ni, Sr, Zr, Mo, La, Ce, Nd and U, respectively. High accuracy of the analytical results was confirmed by analyzing the refer-ence material of glass (NIST SRM1412) and a simulated inactive waste glass. The analytical results of the high-level radioactive waste glass were in good or fair agreement with the values estimated by British Nuclear Fuels plc, which were calculated from the analytical data of the high-level radioactive liquid waste and glass frit used in the production of the radioactive waste glass.

View full abstract

A simple and rapid determination method for trace amounts of copper and lead in water and rock samples by tungsten metal furnace atomic absorption spectrometry was investigated. Copper and lead were quantitatively collected on activated carbon impregnated with 1,2-cyclohexanediondioxime (AC-Dox) at pH 5.0 for copper and pH 8.0 for lead. The copper and lead collected on an AC-Dox were eluted with 1 mol dm^-3 hydrochloric acid, and the absorbances of the eluents were measured at 324.8 nm for copper and 283.3 nm for lead, respectively. The detection limit (S/N=3) for copper was 0.013 µg/5.0 cm³ and that for lead was 0.075 µg/5.0 cm³. The relative standard deviations (n=5) were 2.0 - 4.0% for each metal.

View full abstract

During a differential pulse polarographic determination of selenium, the selenite peak was diminished upon the addition of some ions, such as lead, copper and cadmium. On the other hand, the addition of selenite ion had the same effect on the peaks of the mentioned ions. In both cases a new reduction peak appeared at a more positive potential with respect to the selenite and present ion reductions. This observation is attributed to an intermetallic compound formation between selenium and the ions present. The peak is brought about by a reduction of the lead ion, which afterwards forms an inter-metallic compound with selenium adsorbed on the mercury-drop surface (Pb²⁺+Se_(ads)+2e ⇔ PbSe_(ads)). Temperature-dependence studies also revealed that the observed phenomenon is a surface reaction.

View full abstract