Masao Maruyama

Electrochemical behavior of nitrogen heterocycles in N,N-dimethylformamide-water and aqueous buffer solution

Abstract The electrochemical behavior of ten nitrogen heterocycles was investigated in DMF-water and aqueous buffer solution. On the basis of these data, the effect of proton on the reduction behavior in DMF-water media and the reduction pathway in aqueous buffer solution ware phenomenologically classified. The adsorption phenomena in aqueous buffer solution and the correlation of reduction behavior with structure and reactivity were discussed. The structure of electrolytic products was also estimated and identified by negative electron density distributions of radical anion, GC-MS and spectrophotometry.

Residue analysis of ethylenethiourea in vegetables by high-performance liquid chromatography with amperometric detection

SummaryA method for the residue analysis of ethylenethiourea (ETU) in vegetables by HPLC with amperometric detection was developed. ETU was separated with Nucleosil C18 as stationary phase and methanol-water (5:95, v/v) containing 0.05 mol/l ammonium acetate as eluent. The voltage of the working electrode (glassy carbon) was set at +1150 mV vs. Ag/AgCl. The limit of detection for ETU was found to be 0.3 ng. The method was applied to the determination of trace amounts of ETU in tomatoes and cucumbers. The minimum quantitation level was 0.01 ppm. The method can be performed easily; it is selective and highly sensitive.

Determination of a small amount of niacin in foodstuffs by high-performance liquid chromatography

A high-performance liquid chromatographic method for the determination of a small amount of niacin in foodstuffs is described. This method is based on hydrolysis of sample, extraction, clean-up (anion-exchange and cation-exchange columns) and separation from interferences by chromatography on an amino phase column. The detection limit of niacin in foodstuff is about 0.01 mg per 100 g. The results of analysis of foodstuffs by this method are in good agreement with those obtained by the microbiological method.

Reversed-phase liquid chromatographic behaviour of alkylamines with amperometric detection and its application to trace analysis

Abstract The reversed-phase liquid chromatographic behaviour of tri- and dialkylamines with amperometric detection was studied. Peak retention and peak shape can be improved by the addition of ammonium ion (as competing base) to the mobile phase. The retention behaviour of alkylamines can be explained by both ion and solvophobic interactions. This method can be applied to the selective and sensitive determination of trace amounts of tri- and dialkylamines. In air samples the limit of determination of trimethylamine is a few μg/l and in water samples (direct injection) a few tenths of 1 mg/l.

Determination of trace amounts of 3,4-dichloroaniline by high-performance liquid chromatography with amperometric detection and its application to pesticide residue analysis

SummaryHigh-performance liquid chromatography with amperometric detection was used for the determination of trace amounts of 3,4-dichloroaniline. The latter was separated with Nucleosil C18 as stationary phase and methanolwater (70:30 V/V) containing 0.05 mol/l ammonium acetate as eluent. The voltage of the working electrode (glassy carbon) was set at +960 mV vs. Ag/AgCl. The linear dynamic range between limiting current and concentration was about 1×102 (0.2–20 ng) and the minimum detectable amount was 0.2 ng. This method was applied to the determination of trace amounts of linuron and free 3,4-dichloroaniline in potatoes. The minimum quantitative level was 0.01 ppm. The method requires less clean-up steps than the GC and HPLC methods (using UV detection).

Flame photometric determination of bromine in organic compounds by band spectra of cuprous bromide

ZusammenfassungFür die flammenphotometrische Bestimmung von Brom in organischen Verbindungen wurde als Lösungsmittel ein kupferhaltiges Dimethylformamid — Aceton-Gemisch (1∶1) benutzt. Das Bandenspektrum von Kupfer(I)bromid, mit einem Maximum bei 434.1 nm wurde für die Messung herangezogen.Um ein stabiles und intensives Spektrum von Kupfer(I)bromid zu erhalten, mußte das Verbrennungsgas einen hohen Sauerstoffdruck (0.70 kg/cm2) und eine niedrige Strömungsgeschwindigkeit des Wasserstoffs (800 ml/min) aufweisen. Als Standard-Bromverbindung wurde p-Dibrombenzol verwendet. Die Methode wurde an 14 verschiedenen organischen Bromverbindungen mit gutem Erfolg geprüft (Wiederfindung 93.0–106.4%). Der optimale Konzentrationsbereich von Brom beträgt 0.025–0,2 M.SummaryThe determination of bromine in organic compounds by flame photometry was attempted by using as a solvent dimethylformamide: acetone mixture (1∶1) containing copper and a cuprous bromide band peak of 434.1 nm. In order to obtain a stable and intense cuprous bromide spectrum, combustion gases were maintained at high oxygen pressure (0.70 kg/cm2) and low hydrogen flow rate (800ml/min). p-Dibromobenzene was used as the standard bromine compound and determination was carried out with 14 types of organic bromine compounds with good results (93.0–106.4% recovery). The determinable concentration range of bromine is 0.025–0.2 mol.

Gas Chromatographic Analysis of Methyl Esters of Long-Chain Fatty Acid by Using Polyvinyl Acetates as Partition Media.

不飽和結合をもつ高級脂肪酸メチルエステルのガスクロマトグラフィーに使用する固定相としてクロトン酸変性ポリ酢酸ビニルを結合剤を兼ねた液相とし,セライト545の粉末を固めて30～40メッシュの大きさの穎粒に造粒したものを用いて分析をおこなった。この固定相によりC 1 8 の脂肪酸, ステアリン酸, オレイン酸, リノール酸, およびリノレン酸のメチルエステルを完全に分離することができた。相対保持容量はステアリン酸メチルを1とするとそれぞれ1.13,1.36,1.69であり,分離能もポリエステル系のReoplex400などの固定相と対比しうるのみならず,原料は市販品として容易に入手でき,またセライト545は粉末を利用するため高級脂肪酸メチルエステルの分析に広く利用しうるものと考えられる。この固定相による脂肪酸組成の分析例として,数種の植物油および生体組織中の脂肪酸をメチルエステルとし,ガスクロマトグラフィーをおこなった結果を示した。