Masashi Komata

A highly sensitive spectrophotometric determination of cadmium with α,β,γ,δ-Tetrakis(4-N-trimethylaminophenyl)-porphine

Abstract A new and highly sensitive reagent is proposed for spectrophotometric determination of cadmium. α,β,γ,δ-Tetrakis (4-N-trimethylaminophenyl) porphine forms a chelate with cadmium in alkaline solution with a molar absorptivity of 5.77 × 105l. mole−1.cmt1, the largest value reported to date for a cadmium complex. An extraction method is described for selective separation of cadmium.

Novel analytical applications of porphyrin to HPLC post-column flow injection system for determination of the lanthanides

A novel indirect substitution spectrophotometric methodology using porphyrin is developed for the determination of some metals that do not react with porphyrin directly. The methodology is concerned with a multistep reaction system, which consists of 3 complexation reactions that occur in a sequence of EDTA with metal, EDTA with Cu(II) and porphyrin with Cu(II). The complexation reaction of Cu(II) with a cationic porphyrin, meso-tetrakis (4-N-trimethylaminophenyl)-porphine (ttmapp), which has a high molar absorptivity about 5 x 10(5)l mol(-1)cm(-1), serves for spectrophotometric detection. This methodology was verified through individual determinations of 14 species of lanthanides following a batchwise procedure, which was further developed to an automatic procedure on a HPLC post-column flow injection system for simultaneous analysis of the lanthanides. Compared with the conventional post-column derivatization method using 4-(2-pyridylazo) resorcinol (PAR), the analytical sensitivity was greatly improved in this method and the results also showed good linearity.

Electrooxidative Cyclization of Hydroquinolyl Alcohols, Hydroquinolylamines, and Dimethyl Aminomalonates

Several hydroquinolyl alcohols and amines were electrochemically oxidized in methanol in the presence of sodium methoxide and potassium iodide to afford the corresponding intramolecular cyclization products. Furthermore, several amino malonates were electrochemically oxidized to yield the corresponding heterocyclic compounds through an intramolecular carbon–carbon bond formation in the presence of sodium cyanide in methanol.

Anodic Oxidation of Ketone Allylhydrazones into the Corresponding Azines

Abstract Several ketone allylhydrazones were electrochemically oxidized in methanol in the presence of sodium methoxide and potassium iodide to afford the corresponding azines. The electro-oxidation involves formation of a new carbon–nitrogen double bond between an allylic carbon atom and the nitrogen atom of a hydrazone to afford a conjugated system. Optimal yields were obtained when 0.5 equivalents of sodium methoxide and a catalytic amount of potassium iodide were used as the supporting electrolyte at room temperature. Presumably, the electro-oxidation involves a two-electron oxidation process where the iodide ion functions as electron carrier.

Concentration of metal chelate on a membrane filter using surfactant

The most sensitive metal reagents, water-soluble porphyrins with anionic side-chain, and cationic side-chain and their metal complexes were found to be associated by the surfactants with opposite charges and to be collected on membrane filters quantitatively. The ion-associates were dissolved in a few ml of H2SO4/DMF together with the filter paper, and the absorbance of the solution was readily measured. Concentration of 1/200 to 1/1000 of original volume was possible. Determination of 50 to 500 ng/1 level of copper ion will be presented.

Isolation and antiviral activity of water-soluble Cynomorium songaricum Rupr. polysaccharides

The plant, Cynomorium songaricum Rupr., is used as a traditional medicine in China and Mongolia. In the present study, two new water-soluble polysaccharides isolated from C. songaricum Rupr. were purified by successive Sephadex G-75 and G-50 column chromatographies and then characterized by high resolution NMR and IR spectroscopies. The molecular weights of two polysaccharides were determined by an aqueous GPC to be = 3.7 × 104 and 1.0 × 104, respectively. In addition, it was found that the polysaccharide with the larger molecular weight was an acidic polysaccharide. It was found that the iodine-starch reaction of both isolated polysaccharides was negative and the methylation analysis gave 2, 4, 6-tri-O-methyl alditol acetate as a main product. NMR and IR measurements and sugar analysis revealed that both polysaccharides had a (1 → 3)-α-d-glucopyranosidic main chain with a small number of branches. After sulfation, the sulfated C. songaricum Rupr. polysaccharides were found to have a potent inhibitory effect on HIV infection of MT-4 cells at a 50% effective concentration of 0.3-0.4 μg/ml, a concentration that has almost the same high activity as standard dextran and curdlan sulfates, EC50 = 0.35 and 0.14 μg/ml, respectively. The 50% cytotoxic concentration was low, CC50>1000 μg/ml. In addition, the interaction between the sulfated polysaccharides and poly-l-lysine as a model protein compound was investigated by a surface plasmon resonance to reveal the anti-HIV mechanism.

Simultaneous analysis of NOx and SOx in ambient air by pre-concentration ion-chromatography

濃縮イオンクロマトグラフ法を用いて大気中のNOx, SOxの測定法について検討した.一定容量 (5l) の試料吸収瓶に試料を採取し吸収液50ml, 及びオゾン10mlを加えて酸化吸収させた後, 濃縮イオンクロマトグラフで硝酸イオン, 硫酸イオンを測定してNOx, SOxを定量した.大気中のNOx, SOxの同時定量が可能であった.大気試料での, NOx (NO2として) 定量の相対標準偏差は4.03%, SOx (SO2として) 定量の相対標準偏差は3.16%であった.

A quick method for the determination of phosphorus in organic compounds by the photochemical decomposition-ion chromatography.

Various kinds of organic phosphorus compounds in aqueous solution were photochemically decomposed by ultraviolet irradiation and the phosphate ion produced was determined by ion chromatography. Hydrogen peroxide was added to the sample solution, which was prepared by adding methanol solution of phosphorus compounds to water. The mixture was, then, irradiated for 30-90 min under bubbling of O2 gas. It took 30 min to decompose quantitatively most of phosphorus compounds When a sample contained halogen and/or sulfur, proposed photochemical decomposition-ion chromatography method makes it possible to determine these elements simulteneously as X-, SO42- and PO43-.