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%.

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 %.

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.

The determination of phosphorus in organic compounds with potentiometric end-point detection

1970 ◽  
Vol 58 (1) ◽  
pp. 52-57 ◽  
Author(s):  
J. Slanina ◽  
P. C. M. Frintrop ◽  
J. F. Mansveld ◽  
B. Griepink
Keyword(s):  
Organic Compounds ◽  
End Point ◽  
End Point Detection ◽  
Point Detection

Determination of titratable acidity of wines and total acidity of vinegars by discontinuous flow analysis using photometric end-point detection

The Analyst ◽  
1991 ◽  
Vol 116 (10) ◽  
pp. 1051 ◽  
Author(s):  
Terence J. Cardwell ◽  
Robert W. Cattrall ◽  
Graeme J. Cross ◽  
Gregory R. O'Connell ◽  
John D. Petty ◽  
...  
Keyword(s):  
Flow Analysis ◽  
Titratable Acidity ◽  
Total Acidity ◽  
Discontinuous Flow ◽  
End Point ◽  
End Point Detection ◽  
Point Detection

scholarly journals Coulometric-potentiometric determination of pKA of several organic bases in propylene carbonate

2008 ◽  
Vol 73 (6) ◽  
pp. 655-659
Author(s):  
Ljiljana Jaksic ◽  
Radmila Dzudovic
Keyword(s):  
Propylene Carbonate ◽  
Supporting Electrolyte ◽  
Sodium Perchlorate ◽  
Potentiometric Method ◽  
Potentiometric Determination ◽  
Pka Values ◽  
Reference Base ◽  
Organic Bases ◽  
Standard Base

The pKA values of protonated triethylamine, pyridine and 2,2'-dipyridyl in propylene carbonate (PC) were determined by applying the coulometric-potentiometric method and a hydrogen/palladium generator anode (H2/Pd). The investigated and reference base were titrated to 50 % with protons electro-generated from hydrogen-saturated palladium, in the presence of sodium perchlorate as the supporting electrolyte. The half-neutralization potentials E1/2(x) and E1/2(st.) of the investigated and standard base, respectively, were measured using a glass-SCE pair. The obtained pKA values were compared with those reported in the literature.

Semi-automatic end-point detection in the determination of total hardness in water

1983 ◽  
Vol 149 ◽  
pp. 401-403 ◽  
Author(s):  
Athos Bellomo ◽  
Alessandro de Robertis ◽  
Carlo D'Arrigo
Keyword(s):  
Total Hardness ◽  
End Point ◽  
End Point Detection ◽  
Point Detection
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