scholarly journals Coulometric generation of H+ ions by the anodic oxidation of esters of gallic acid

2005 ◽  
Vol 70 (2) ◽  
pp. 243-249 ◽  
Author(s):  
Ljiljana Jaksic ◽  
Radmila Dzudovic ◽  
Randjel Mihajlovic
Keyword(s):  
Gallic Acid ◽  
Aqueous Media ◽  
Sodium Perchlorate ◽  
Indicator Electrode ◽  
Dodecyl Gallate ◽  
Oxidation Potentials ◽  
End Point Detection ◽  
Point Detection ◽  
Current Potential ◽  
Potential Curves

The application of esters of gallic acid (propyl, butyl and dodecyl gallate) for the coulometric generation of H+ ions in aqueous media is described. The current-potential curves recorded for these depolarizers, as well as for tris(hydrosymethyl) aminomethane (?THAM?) and the employed solvent showed that the investigated depolarizes are oxidized at potentials lower than the oxidation potentials of the other components in the solution. The H+ ions formed by the oxidation of these depolarizers (in 1 mol/L sodium perchlorate in water) were used for the titration of THAM with potentiometric end-point detection using a hydrogen/palladium indicator electrode. The current efficiency was 100 %.

scholarly journals Coulometric titrations of bases in propylene carbonate and γ-butyrolactone using hydroquinone as the depolarizer and a quinhydrone indicator electrode

2000 ◽  
Vol 65 (8) ◽  
pp. 587-593 ◽  
Author(s):  
Lj.N. Jaksic ◽  
R.M. Dzudovic ◽  
R.P. Mihajlovic ◽  
Z.D. Stanic
Keyword(s):  
Propylene Carbonate ◽  
Platinum Electrode ◽  
Indicator Electrode ◽  
Hydrogen Ions ◽  
Organic Bases ◽  
Oxidation Potentials ◽  
End Point Detection ◽  
Point Detection ◽  
Current Potential

The application of hydroquinone for the coulometric generation of hydrogen ions in propylene carbonate (PC) and ?-butyrolactone (GBL) is described. The current-potential curves recorded for this depolarizer, titrated bases, indicator and the solvents used showed that the investigated depolarizer is oxidized at lower potentials than the oxidation potentials of other components in the solution. The hydrogen ions generated by the oxidation of hydroquinone were used for the titration of organic bases (triethylamine, n-butylamine, pyridine, quinoline, aniline, N,N'-diphenylguanidine, piperidine, and 2,2?-bi?pyridine) in PC and GBL with with visual (Crystal Violet as indicator) and potentiometric end-point detection using a quinhydrone electrode as the indicator electrode. The quinhydrone added to the to be analyzed solution served both as a source of hydrogen ions and, together with the immersed platinum electrode, as a quinhydrone electrode. The relative error of the determination of the bases was about 1%.

Potentiometric Titration of Triazolethiols and Tetrazolethiols with Iodine in Alkaline Medium

2002 ◽  
Vol 67 (8) ◽  
pp. 1193-1199 ◽  
Author(s):  
Witold Ciesielski ◽  
Anna Krenc
Keyword(s):  
Potentiometric Titration ◽  
Alkaline Medium ◽  
Potential Drop ◽  
Potentiometric Titration Curve ◽  
Indicator Electrode ◽  
Nernst Equation ◽  
Relative Standard ◽  
End Point Detection ◽  
Point Detection

The iodimetric determination of triazolethiols and tetrazolethiols in alkaline medium is presented. The volumetric titration with potentiometric end-point detection was applied. The range of determination, in which the error is lower than 1%, is 20-2 000 μmol for 1H-1,2,4-triazole-3-thiol (1), 25-1 000 μmol for 3-phenyl-1H-1,2,4-triazole-5-thiol (2), 25-500 μmol for 4-methyl-5-(trifluoromethyl)-4H-1,2,4-triazole-3-thiol (3), 50-500 μmol for 3-amino-1H-1,2,4-triazole-5-thiol (4), 10-1 000 μmol for sodium (5-mercapto-1H-tetrazol-1-yl)acetate (5), 125-500 μmol for 1-phenyl-1H-tetrazole-5-thiol (6) and 50-1 000 μmol for 1-(4-hydroxyphenyl)-1H-tetrazole-5-thiol (7). The relative standard deviation for all determinations was below 1%. The shape of potentiometric titration curve of 6 and 7 is noteworthy at higher concentrations of sodium hydroxide and depends on the type of the indicator electrode (platinum, gold). An introduction of iodine results in a strong potential drop. Some systems do not follow the Nernst equation.

scholarly journals Acid number, viscosity and end-point detection in a multiphase high temperature polymerisation process using an online miniaturised MEMS Fabry-Pérot interferometer

Talanta ◽  
2021 ◽  
Vol 224 ◽  
pp. 121735
Author(s):  
Claudio Avila ◽  
Christos Mantzaridis ◽  
Joan Ferré ◽  
Rodrigo Rocha de Oliveira ◽  
Uula Kantojärvi ◽  
...  
Keyword(s):  
High Temperature ◽  
Acid Number ◽  
End Point ◽  
Fabry Perot ◽  
End Point Detection ◽  
Point Detection

Fluoroimmunoassay for human choriomammotropin.

1979 ◽  
Vol 25 (6) ◽  
pp. 973-975 ◽  
Author(s):  
T Chard ◽  
A Sykes
Keyword(s):  
Equipment Design ◽  
Radiation Hazard ◽  
Human Origin ◽  
End Point ◽  
End Point Detection ◽  
Purified Antigen ◽  
Point Detection

Abstract We describe an immunoassay for human choriomammo-tropin by use of the fluorescein-labeled hormone (of human origin). The technique is generally similar to the radioimmunoassay for this material, but has the advantage of stability of tracer and avoidance of radiation hazard. However, the procedure requires approximately 50-fold more tracer than does the radioimmunoassay, and this would be a disadvantage with materials for which supplies of purified antigen are scarce. Furthermore, both within-assay variation (3.9%) and between-assay variation (7.8--7.9%) were less satisfactory than that of radioimmunoassay (1.5% and 2.2--3%, respectively). This is almost certainly the result of imprecision of end-point detection and could probably be corrected by further attention to equipment design.

AEROBIC END-POINT DETECTION IN A SEQUENCING BATCH REACTOR

2005 ◽  
Vol 38 (1) ◽  
pp. 115-120
Author(s):  
Hilario López García ◽  
Iván Machón González
Keyword(s):  
Sequencing Batch Reactor ◽  
Batch Reactor ◽  
End Point ◽  
End Point Detection ◽  
Point Detection

Optical end point detection of etched YBCO films

1992 ◽  
Vol 191 (3-4) ◽  
pp. 525-529 ◽  
Author(s):  
R. Dolata ◽  
M. Fischer ◽  
W. Jutzi
Keyword(s):  
Ybco Films ◽  
End Point ◽  
End Point Detection ◽  
Point Detection
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