All issues
Volume 16 (1969 - 197･･･
- Issue 6 Pages 109-
- Issue 5 Pages 85-
- Issue 3-4 Pages 43-
- Issue 1-2 Pages 1-
Predecessor
Volume 16, Issue 3-4
Displaying 1-4 of 4 articles from this issue
- |<
- <
- 1
- >
- >|
-
Masanosuke TAKAGI1969 Volume 16 Issue 3-4 Pages 43-60
Published: 1969
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSConventional determination methods of carbonyl groups in starches are criticized from the practical point of view. The necessity of new methods and the applicability of polarographic methods are discussed. Inapplicability of polarographic method as a direct method of determination for even glucose, monomer of starch and related carbohydrates, is presented and the possibility of indirect methods converting the carbohydrate to electroactive epecies is emphasized.Indirect methods of determination of carbonyl compounds are reviewed and related to the present determination methods based on the formation of quinoxalines from the reaction of the carbohydrate with o-phenylenediamine (OPD).General polarographic behavior of quinoxalines is reviewed.The polarographic OPD method is presented in detail : condition for the reaction of the carbohydrate with OPD, the formation of 2-methylquinoxaline from the reducing end of all the a-l, 4 glucosides and the extraction of the quinoxaline with nhexane or petrolium ether, the linearity of the total limiting current with the reciprocal polymerization degree under fixed conditions. etc.Application of the methods to the determination of number-average molecular weight of amylose, amylopectin and other related carbohydrates are described and compared with those obtained by other methods.The method is also applicable to the determination of carbonyl groups in periodate oxidized starches.View full abstractDownload PDF (2134K) -
Takeshi ISHII, Soichiro MUSHA1969 Volume 16 Issue 3-4 Pages 61-68
Published: 1969
Released on J-STAGE: October 21, 2011
JOURNAL FREE ACCESSIn view of the well known fact that dissolved oxygen plays a very important role in petroleum refinery, the present investigation was undertaken to establish a rapid and accurate method for the determination of dissolved oxygen in gasoline . In 1924 Heyrovsky first reported that dissolved oxygen is reduced at the dropping mercury electrode to produce two waves3) . The first wave results from reduction to hydrogen peroxide :
O2+2H++2e→H2O2(acid medium)
O2+H2O2+2e→HO2-+OH-(neutral or alkaline medium).
The second wave corresponds to the reduction of the hydrogen peroxide either to water or hydroxyl ion, depending on the pH:
H2O2+2erarr;2H2O(acid medium)
HO2-→3OH-(alkaline medium).The diffusion currents are normally well-defined and show a linear dependence on oxygen concentration. However, three main difficulties are encountered in the application of a.c, polarography to the determination of oxygen in gasoline: the limited solubility of gasoline in aqueous or semi-aqueous electrolyte system, the exclusion of atmospheric oxygen in handling sample and the accurate calibration of calibration curve. The first difficulty was resolved by adopting a supporting electrolyte of sodium hydroxide in absolute alcohol and the second by the disign of a special polarographic cell. Two ways of accurate calibration were investigated: by using water of known dissolved oxygen content directly as a calibration standard, and by using air-saturated alcoholic electrolyte as a secondary standard, the dissolved oxygen content being determined polarographically using water as a primary standard .View full abstractDownload PDF (792K) -
Junsuke SUZUKI1969 Volume 16 Issue 3-4 Pages 69-74
Published: 1969
Released on J-STAGE: October 21, 2011
JOURNAL FREE ACCESSAn equation for the diffusional flux in the laminar flow at the plate electrode, in which the electrode reaction takes place only on a portion of the surface of the plate, was derived theoretically on the basis of the hydrodynamic conceptions developed by Levich . Applying the theoretical treatment of Levich to the platinum plate convection electrode (PPCE), the equation of the limiting current is obtained as follows:
iι=0.355nFAc0D2/3υ1/2ν-1/6{(1+x1/a)3/4-(x1/a)3/4}-2/3
In the case that a/x1« the limiting current is given by iι=0.355nFAc0D2/3υ1/2ν-1/6a-1/3x1-1/6
Using a 2 x 10-4M hexacyanoferrate (II) solution, the experimental confirmation for the theoretical equation mentioned above was carried out. The results indicated that the limiting current at PPCE obeyed the equation. This shows that the velocity of the fluid flow is proportional to the tangential velocity of the rotating disk, that is, the value of the proportional constant is 0.40, which is the same value obtained in the previous work.View full abstractDownload PDF (642K) -
Tsal-Teh LAT, Tsung-Yu CHEN1969 Volume 16 Issue 3-4 Pages 75-84
Published: 1969
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSThe polarographic behaviours of uranyl-dimethyl sulfoxide and uranyl-fumarate-dimethyl sulfoxide systems were studied at 30°C. For the former system, the complex species of UO2Dm+2, UO2(Dm)2+2 and UO2(Dm)4+2 were identified. For the latter system, the existences of (UO2)2 (HFu)2Dm+2, UO2(HFu)(Dm)2+1 and UO2Fu(Dm)2 were confirmed and their electrode reactions were established.The poor solubility of the chelating agent in water medium is an obstacle to the polarographic studies of metal chelates. Various kinds of non-aqueous media, there-fore, have been used to substitute water solution. Among them dimethyl sulfoxide has recently come to be widely used as an advantageous medium.The polarographic behaviours of lanthanides and thorium in dimethyl sulfoxide were studied, respectively, by Gritzner et al. and Sancho and co-workers. Some uranyl complexes with dimethyl sulfoxide have been prepared.In the present paper the reduction of uranyl ion in various concentration of dimethyl sulfoxide at dropping mercury electrode was first carried out, and then a further polaro-graphic study of uranyl-fumarate system in dimethyl sulfoxide solution was made.View full abstractDownload PDF (840K)
- |<
- <
- 1
- >
- >|