Tsutomu Matsuo

Kinetic determination of traces of manganese(II) by its catalytic effect on the oxidation of acid blue 45 with hydrogen peroxide

Abstract A catalytic method is described for the determination of trace amounts of manganese(II) based on its catalytic effect on the hydrogen peroxide oxidation of an anthraquinone dye, Acid blue 45 (C.I. 63010). The reaction is followed spectrophotometrically by measuring the rate of change in absorbance of the dye at 595 nm. The calibration graph (rate constant (tg α) vs. manganese concentration) is linear in the range 4–25 ng Mn ml −1 , the relative standard deviation being 1.9% at the 13 ng Mn ml −1 level. There are few interferences. The kinetic parameters of the reaction were investigated and the role of hydrogen peroxide and hydrogencarbonate ions is discussed.

Acid-base and chelatometric photo-titrations with photosensors and membrane photosensors

Photosensors (PS) and membrane photosensors (MPS), which can be immersed in the test solution and facilitate the measurement of concentration, have been developed by miniaturizing an optical system consisting of a light source and a photocell. For use in acid-base or complexometric titrations a poly(vinyl chloride) membrane containing an acid-base or metallochromic indicator can be applied as a coating to the photocell. Spectrophotometric determination of copper(II), and photometric acid-base and chelatometric titrations have been performed with the PS and MPS systems.

Collection of Trace Fluoride and Hydrofluoric Acid from Aqueous Samples by Calcium Hydroxyapatite

Abstract A selective method for preconcentrating trace fluoride ions from aqueous environmental and analytical samples by calcium hydroxyapatite is described. Studies have been performed with batch and column equilibration and the optimum conditions are determined with respect to the pH, contact time and coexisting anion concentration. The addition of acetate buffer is recommended for effective uptake of fluoride. The difficulties that solid hydroxyapatite particles deform or collapse and column permeability decreases during column operations have been overcome with the use of polyacrylamide-blended hydroxyapatite. Batch procedures allow the quantitative recovery of fluoride (50-500 μg) from a 100-fold excess of aluminium ions by 1 gramme of hydroxyapatite.

Polarographic studies of copper(II) complexes with N,N'-bis(2-hydroxyethyl)ethylenediamine-N,N'-diacetic acid

The polarographic behaviour of Cu(II)-N,N′-bis(2-hydroxyethyl)ethylenediamine-N,N′-diacetic acid (H2bhedda=H2L) complexes has been investigated in detail. De polarograms of Cu(II)−H2 bhedda systems gave two well-defined waves in an excess of the metal ion in the pH range 3–9. The first wave (e.g. 0.034 V vs. SCE, pH=3.29) is due to the reversible reduction of Cu(II) for any pH studied. The electrode process for the second wave (−0.205 V vs. SCE pH=3.55) changed from an irreversible electron transfer process (pH<5) to a reversible one (pH≥5) with increasing pH. Both limiting currents for wave A and B were diffusion controlled. Logarithmic stability constants of Cu(II)−H2 bhedda complexes were calculated using the data from the polarography (log KCuHL=5.24) and the potentiometric titration (log KCuL=11.3). The composition of Cu(II)−H2 bhedda complexes was determined by the amperometric or potentiometric titration (CuL or CuHL+). Electrode reaction mechanisms for the second wave are elucidated as follows: 3.0 7.0, CuL+2e+HgCu(Hg)+L2− (III) The standard rate constant of mechanism (I) was also obtained (kj=2.04×10−4 cm s−1). The frequency effect on the “cut-in” height for the complex was examined with the frequency variable Heyrovský-Forejt type oscillopolarograph. The electrode reaction rate constants for various Cu(II)-polyaminepolycarboxylic acid systems were also studied by oscillopolarography.

Determination of tin in lead alloys by atomic absorption spectrometry

空気-アセチレン炎を用いるスズの原子吸光分析定量において,アセチレン流量ならびに酸(有機酸を含む)の影響について調べた.また錯形成剤としてピロリジンジチオカルバミン酸アンモニウム,ジエチルジチオカルバミン酸ナトリウムおよびジチオールを用い,生成したスズ錯体をメチルイソブチルケトンにより抽出し,MIBK溶液を噴霧した.抽出溶液を用いるときには水溶液を用いたときに比べて定量感度が約3.5倍増大することを認めた。本法により二,三の鉛合金中のスズを定量して満足な結果を得た.