Tsuneo Shirai

Fibre-optic potassium ion sensors based on a neutral ionophore and a novel lipophilic anionic dye

Abstract A novel lipophilic anionic dye, N -2,4-dinitro-6-octyloxyphenyl-2′,4′-dinitro-6′-trifluoromethylphenylamine (LAD), was synthesized. On deprotonation at neutral Ph it forms anions and brings about a change in the absorption spectrum in the visible region. This anionic dye was incorporated into a poly(vinyl chloride) matrix membrane with dibenzo-18-crown-6 (DB18C6) or valinomycin, which are K + -selective neutral ionophores. An optical K + sensor was prepared using the polymeric membrane set 1 mm apart from the tip of a bifurcated optical fibre with a cylindrical plastic support. This sensor could detect a wide range of K + concentrations (10 −6 −1 M K + for the DB18C6-based sensor, 10 −8 −10 −2 M K + for the valinomycin-based sensor) at Ph 7.0 by measuring the absorbance change at 513 nm. The factors that influence the response sensitivity of the sensor are discussed theoretically.

Measurement of tire tread in urban air by pyrolysis-gas chromatography with flame photometric detection

Abstract The concentration of tire tread in suspended particulate matter (SPM) was measured by a new method based on benzothiazole generated by pyrolysis of vulcanization accelerator. The variation of production yields of benzothiazole was examined for 24 kinds of tire treads currently used in Japan Pyrolysis was carried out at 670°C using a Curie-point pyrolyzer. The vertical profile and diurnal pattern of tire tread were investigated with 4-h samples continuously collected for 24 h at a heavy traffic density area in Tokyo. The diurnal percentage of tire tread in SPM at the sampling site of 86 m height showed two peaks following the trend of traffic density throughout the day. The concentration of tire tread collected at the 86 m level was about 30% of that at the 0 m level during the daytime. The seasonal variation of concentration of tire tread in SPM was measured at the sampling site located 20 km SW of Tokyo. The weight percentage of tire tread in SPM varied between 1.3 and 3% in winter with NE-NW wind and varied between 0.5 and 1.5% in spring with SE-SW wind.

Response Amplification of an Ion-Selective Electrode

Abstract The response of an ion-selective electrode can be amplified by connecting the cell, which is composed of an ion-selective electrode and a reference electrode, in series. For a cell using 1, 2 or 3 valinomycin electrodes connected in series, the response slopes to 1 × 10−5 −1 × 10−1 M K+ were 58, 116 and 174 mV/activity decade (a.d.) at 25°C, respectively. This amplification method would especially be useful for accurate determinations with electrodes in the range of low concentrations outside the Nernstian response or for determinations of polyvalent ions, in which both cases exhibit small emf response changes in changing the ion concentration.

Characterization of Prussian blue and its thermal decomposition products

The mixed-valence state of Prussian blue and its thermal decomposition products has been studied by Mössbauer and infrared spectra, and X-ray powder diffraction and conductivity measurements. The57Fe Mössbauer spectra have revealed that the coordination environment of Prussian blue is not changed by the heat-treatment at lower than 200°C while the flipping of the cyano ligands takes place when the heat-treatment temperature exceeds 250°C. The electrical conductivity of the Prussian blue samples heat-treated in vacuo at 300 and 350°C is higher than that of the samples heat-treated at lower temperatures. All the spectral measurements have demonstrated that a new mixed-valence state is produced in Prussian blue by thermally flipping the cyano ligand and quenching the flipped cyano ligand to liquid nitrogen temperature.

Barium Ion Selective Electrode Based on Natural Carboxylic Polyether Antibiotic Salinomycin

Abstract An ion-selective electrode based on a naturally ocurring carboxylic polyether antibiotic salinomycin is described which exhibits high Ba2+ selectivity. The selectivity coefficients of the electrode based on salinomycin, log Kpot BaCa, log Kpot BaK and log Kpot BaNa are −2.65, −2.86 and −3.55, respectively.

Determination of pheophytinatonickel(II) by reversed-phase highperformance liquid chromatography

SummaryHPLC determination of pheophytinatonicke(II) (Pheo-Ni) prepared by the replacement of magnesium(II) in chlorophyll with nicke(II) is described. The good separation of PheoNi was obtained by using chemically bonded C18 as the stationary phase and acetone-methanol (50∶50, vol/vol) as the mobile phase. Conventional spectrophotometric method was also used for the determination of PheoNi. For the synthetic samples prepared by mixing (pheophytinato a) nicke(II) [(Pheo-a) Ni] and (pheophytinato b) nicke(II) [(Pheo-b) Ni], analytical values obtained by the spectrophotometric method were very high compared to those obtained by HPLC. In the proposed HPLC method, (Pheo-a) Ni and (Pheo-b). Ni could be determined in the concentration range of 0.028–30μg/ml and 0.038–30μg/ml with relative standard deviations (n=10) of 3.1% and 0.8%, respectively.

Mössbauer sprectroscopic characterization of iron chlorophyllins

The Mössbauer spectra of bis-adducts of pyridine (py) and its derivatives (4-Xpy, where X is CN, CHO, COOCH3, COCH3 and CH3) have revealed that the axial coordination of py and 4-Xpy to iron (III) chlorophyllin gives rise to spontaneous reduction of the central iron (III) ion. A linear correlation between isomer shifts and quadrupole splittings is explained on the basis of the predominant σ-donation from the axial ligand to the central iron ion. The linear dependence of the isomer shifts on the Hammett substituent constants has demonstrated that the larger the isomer shift, the stronger the electron-attracting power of the substituent at the 4-position. The decrease in the quadrupole splitting is ascribed to the relative decrease in the electron density accumulated in the equatorial direction through the σ-donation. The general tendency in the spontaneous reduction of iron (III) chlorophyllin is interpreted in terms of the σ-donor and π-acceptor power of the axial ligands.

Spectroscopic characterization of iron complexes of methyl pheophorbide with pyridine and its derivatives

Abstract A series of (methyl pheophorbide a)iron(II) and -iron(III) complexes have been prepared and characterized by Mossbauer, 1H NMR and electronic spectra. The central iron(III) ion in (methyl pheophorbide a)iron(III) chloride [Fe(mepheo-a)] is in the high-spin state. Autoreduction of the central iron(III) ion in Fe(mepheo-a)Cl is induced by pyridine (py) and its derivatives (4-Xpy). A connection between isomer shifts and quadrupole splittings of Fe(mepheo-a)(4-Xpy)2 indicates the σ-donation from the axial ligands to the central iron(II) ion is predominant in the axial bonding. The linear dependence of the isomer shifts on Hammetts constants of the pyridine substituents (X) and on the pKa values of the free ligands reveals that the, π-backdonation to the axial ligands enhances synergetically the σ-donation to the central iron(II) ion. The linear correlation between the isomer shift and the electronic absorption wavelength demonstrates that the difference in the π-backdonation to the axial ligands affects the π-π* excitations on the chlorin ring via the central iron(II) ion.

Determination of sulfates in urban air by pyrolysis-gas chromatography with flame photometric detection

Abstract An analytical technique has been developed for the determination of sulfates of ammonia (volatile sulfates) in suspended particulate matter (SPM) by pyrolysis-gas chromatography with flame photometric detection (Py-GC/FPD). This method is based on the determination of SO 2 generated by pyrolysis of sulfates, about 30% of which are converted to SO 2 when pyrolysis is performed at 315° C. This technique has several advantages such as small sample size, rapid analysis, simplicity of sample handling and low detection limit (30 ng as sulfur). Atmospheric concentrations of sulfates are measured by Py-GC/FPD and compared with results obtained by ion chromatography (IC). The analytical results of sulfates show a good correlation ( r = 0.920 between Py-GC/FPD and IC. However, the average concentrations of sulfates obtained by PY-GC/FPD are 18% higher than the results of water soluble sulfates (WSS) obtained for daytime samples (7:00–19:00) by IC. In contrast, the concentrations of sulfates in night-time samples (19:00-7:00) obtained by Py-GC/FPD are 12% lower than those of WSS obtained by IC. These analytical results demonstrate that Py-GC/FPD is a useful technique for specific analysis of sulfates of ammonium amongst various types of sulfates. However, a contribution of sulfur-containing components other than sulfates to SO 2 cannot be neglected when Py-GC/FPD is used.

Infrared, 57Fe Mössbauer, and 31P NMR Spectroscopic Characterization of Fe(CO)4L (L = Phosphine and Phosphite)

A series of trigonal bipyramidal Fe(CO)4L complexes has been prepared and characterized by infrared, 57Fe Mössbauer and 31P NMR spectroscopy. A linear correlation, with a negative slope, between the CO stretching frequencies and the isomer shifts demonstrates that the triple bond nature of the carbonyl ligands is strengthened with increasing iron-to-phosphorus back donation. The linear dependence of the quadrupole splittings on the isomer shifts with a positive slope has revealed that the σ-donor capability of the phosphine or phosphite ligand is offset by the π-acceptor capability. The formation of Fe(CO)4L complexes from the corresponding free ligands is accompanied by a downfield shift of 31P NMR chemical shifts. The coordination shifts are linearly correlated with the Mössbauer isomer shifts.