Akinori Kawahara

Separation of aniline derivatives by micellar electrokinetic chromatography

Abstract The separation of ten aniline derivatives was investigated by micellar electrokinetic chromatography. The pH dependence of their migration behaviour wa

Perchlorate-selective electrodes with urushi as the membrane matrix

Abstract Perchlorate-selective electrodes prepared from a new matrix, Urushi, and tri-n-octylmethylammonium perchlorate or the Corning perchlorate liquid ion-exchanger are described. The electrodes have linear response ranges and selectivity similar to those of commercial perchlorate-selective electrodes. The membranes are hard, lustrous and smooth; their useful lifetimes exceed 1000 h.

Methods for the preparation and characterisation of a selenocyanate ion-sensitive field effect transistor with Urushi as the membrane matrix

A selenocyanate ion-sensitive field effect transistor (ISFET) was fabricated from a silicon wafer with Urushi (natural lacquer) as the membrane matrix. The proposed ion sensor has excellent durability for over 2 months. The ISFET can be characterised by the relationship between the square root of the drain current and the logarithm of the ion activity in the saturation region of the ISFET. It was found that the linear response range of the Urushi ISFET was from 10–5 to 10–1M selenocyanate ion activity and the selectivity coefficients were almost the same as those of the Urushi ion-selective electrode.

A new selenocyanate-selective electrode based on an Urushi matrix-membrane

ZusammenfassungEine Selenocyanat-selective Elektrode wurde aus einem Tri-n-octylmethylammonium-Selenocyanat-Austauscher und einer Urushi-Matrix hergestellt. Lineare Potential-Konzentrations-Kurven wurden im Konzentrationsbereich 10−1 bis 10−5 mol/l Selenocyanat erhalten. Bei Einsatz von 45–50% Tri-n-octylmethylammonium-Selenocyanat und 55-50% rohem Urushi-Latex betrug die Neigung des linearen Teils der Potential-Konzentrationskurve 60 mV pro Zehnerpotenz Selenocyanatkonzentration. Die statische Ansprechzeit war weniger als 30 s. Die Elektrode wies im pH-Bereich von 2–10 ein konstantes Potential auf. Der Selektivitätskoeffizent wurde nach der Methode der Lösungsgemische gemessen. Die Elektrode wurde angewendet zur Messung der Bildung von Selenocyanat aus seleniger Säure, Ascorbinsäure und Kaliumcyanid.SummaryA selenocyanate-selective electrode was prepared from tri-n-octylmethylammonium selenocyanate ion-exchanger and a matrix, Urushi. A linear potential-concentration curve was obtained within the concentration range of 10−1–10−5 mol/l selenocyanate. When 45–50 wt% of trin-octylmethylammonium selenocyanate ion-exchanger and 55-50 wt% of raw Urushi latex were used, the slope of the linear part of the potential-concentration curve was 60 mV per decade change of the selenocyanate concentration. The static response time was less than 30 s. The electrode exhibited constant potential within the pH range 2–10. The selectivity coefficient for the electrode was measured with the mixed solution method. The electrode was used for the measurement of the formation of selenocyanate from selenious acid, ascorbic acid and potassium cyanide.

Determination of phosphate ion using lead ion-sensitive electrode

ZusammenfassungDie Phosphatbestimmung kann im Bereich 10−5 bis 10−1 M bei pH 7–9 in Gegenwart von 0,1 M Natriumperchlorat und 5×10−2 M Ammoniumsulfat/ Ammoniumhydroxid zur Einstellung der Ionenstärke und als Puffer durchgeführt werden. Die Neigung der Eichkurve beträgt etwa −19 mV je Zehnerpotenz der Phosphatkonzentration. Wenige Minuten nach Eintauchen der Elektrode wird eine konstante Anzeige erreicht. Übliche Ionen, wie F−, Cl−, Br−, NO3−, NO2− und HCO3−, haben nur einen geringen Einfluß auf die Bestimmung, während OH−, HAsO42− und J− stören.SummaryA lead ion-sensitive electrode responds to phosphate ion, and is successfully used for the determination of the ion in the concentration range of 10−5–10−1 M at a pH of 7–9 in the presence of 0.1 M sodium perchlorate and 5×10−2 M ammonium sulphate-ammonium hydroxide as ionic strength adjuster and pH buffer, respectively. The slope of the calibration curves is about −19 mV per decade of the concentration. The response reaches equilibrium within several min after immersing the electrode in the phosphate solution. Common anions, as F−, Cl−, Br−, NO3−, NO2− and HCO3s-, have little effect on the determination of phosphate ion, but OH−, HAsO42− and I− affect it.

Hydrogen ion-selective electrode based on an iron-hydroxo-complex

ZusammenfassungDie Membran der vorgeschlagenen ionen-selektiven Elektrode besteht aus einem Eisen(III)-hydroxokomplex, dem Membran-Lösungsmittel und Polyvinylchlorid. Mit 1-Decanol als günstigstem Lösungsmittel ergab sich eine lineare Anzeige von pH 0 bis 5 mit einer Potentialänderung von 56 mV/pH. Die Charakteristik der vorgeschlagenen Elektrode wird beschrieben und der Ansprechmechanismus diskutiert.SummaryA new hydrogen ion-selective based on an iron hydroxo complex was proposed. The ion sensing membrane was composed of the iron(III) hydroxo complex, membrane solvent and polyvinyl chloride. The proposed electrode using 1-decanol as the most favourable solvent showed a linear pH-response from 0 to 5 with a potential change of 56 mV per pH-unit. The characteristics of the proposed electrode and a discussion on the response mechanism are reported.

Measurement of molecular weight distribution pattern of organic substances dissolved in environmental waters by an automatic high-performance gel chromatography.

An apparatus was developed for automatic measurement and to evaluate the pattern of molecular weight distribution of organic substances dissolved in water. A separation column (7.6 mm i.d., 25 mm in length) packed with Asahipak GS-220 was used. Distilled water was used as the mobile phase at flow rate of 1 ml/min, and a chromatogram was obtained by a high sensitive refractive index detector. The apparatus was regulated automatically by a system-controller. Sample size necessary for an analysis was 0.5 ml of filtrated environmental water without preconcentration, and one chromatogram was obtained in twenty minutes. Some enviromental water gave different chromatographic patterns. River water was measured by the apparatus continuously and automatically and chromatograms were obtained once an hour, which showed the change of the patterns from morning to evening. The apparatus was found to be suitable for an automatic measurement of organic substances dissolved in enviromental waters.

Polyvinyl chloride film impregnated with bathophenanthroline for rapid colorimetric determination of ferrous ion in water

ZusammenfassungZur schnellen halbquantitativen Bestimmung von Eisen(II) in Wasser wurde ein transparenter Testfilm entwickelt, der als Reagens Bathophenanthrolin, als Lösungsmittel Tributylphosphat und als Trägermaterial Polyvinylchlorid enthält. Nach Eintauchen in die Probelösung wird die Färbung des Films (die der Eisenkonzentration im Bereich von 0,1–5,6 ppm proportional ist) entweder visuell durch Vergleich mit einer Farbskala oder spektralphotometrisch bei 540 nm gemessen. Noch 0,1 ppm Eisen(II) kann erfaßt werden.SummaryA transparent test film for rapid and semi-quantitative determination of small amounts of ferrous ion in water was prepared. The film is composed of bathophenanthroline, tributyl phosphate and polyvinyl chloride as colour reagent, solvent, and supporting material, respectively. The test film is coloured by immersing into the sample solution, and the colour intensity of the film (proportional to the ferrous concentration in the 0.1 ∼ 5.6 ppm range) is compared visually with a colour scale or measured spectrophotometrically at 540 nm. 0.1 ppm of ferrous ion can be detected.