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.

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 Potentiometric Determination of the Ionization Constant of Nitrous Acid in Aqueous Sodium Perchlorate Solutions at 25 degrees C.

1965 ◽  
Vol 19 ◽  
pp. 617-621 ◽  
Author(s):  
Paavo Lumme ◽  
Jouni Tummavuori ◽  
Ragnar A. Hoffman ◽  
Sören Rodmar ◽  
Kjell Selin ◽  
...  
Keyword(s):  
Nitrous Acid ◽  
Ionization Constant ◽  
Sodium Perchlorate ◽  
Potentiometric Determination ◽  
Aqueous Sodium

Potentiometric determination of pKA of organic bases in acetone by the application of coulometry

Talanta ◽  
1989 ◽  
Vol 36 (11) ◽  
pp. 1154-1156 ◽  
Author(s):  
V.J. Vajgand ◽  
R.P. Mihajlović ◽  
R.M. Džudović
Keyword(s):  
Potentiometric Determination ◽  
Organic Bases

Chromatographic and Surfactant Based Potentiometric Determination of Aqueous Dissociation Constant of Mupirocin

2020 ◽  
Vol 16 (2) ◽  
pp. 158-165 ◽  
Author(s):  
Natalija Nakov ◽  
Katerina Brezovska ◽  
Vasil Karchev ◽  
Jelena Acevska ◽  
Aneta Dimitrovska
Keyword(s):  
Linear Relationship ◽  
Dissociation Constant ◽  
Spectrophotometric Method ◽  
Tween 80 ◽  
Potentiometric Determination ◽  
Chromatography Method ◽  
Pka Values ◽  
Pka Value ◽  
Aqueous Pka

Background: The available data concerning aqueous dissociation constant of mupirocin (sparingly soluble drug) are scarce. In this study, chromatographic, surfactant based potentiometric concept and spectrophotometric method were used for determination of the aqueous pKa value of mupirocin. Methods: Different approaches were used for estimation of the aqueous pKa value from the apparent pKa values obtained at four ACN concentrations, ranging from 22% to 30%. The potentiometric determination of the pKa value of mupirocin was performed using different concentration of Tween 80 as a surfactant. Results: The aqueous pKa value of mupirocin, determined for the first time by reverse-phase liquid chromatography method, was found to be 4.76. The obtained value was confirmed by potentiometric method (4.85). It was found that Tween 80 increases the pKa values. The linear relationship between the apparent pKa values and the surfactant concentrations was used as an approach for estimation of the aqueous pKa value. Both methods gave similar values for aqueous pKa which correspond with the theoretically obtained pKa value (4.88) using Pallas computer program. It was found that mupirocin gives pH-indipendent spectra, thus spectrophotometric method is not applicable for determination of pKa of this compound. Conclusion: This comprehensive approach used for the pKa determination enable us to obtained reliable results for the aqueous pKa value of mupirocin. The linear relationship between the pKa values and the nonionic surfactant concentrations could be used as a reliable and simple approach for determination of aqueous pKa value of sparingly soluble drugs.

scholarly journals Voltammetric Determination of Isopropylmethylphenols in Herbal Spices

Molecules ◽  
2021 ◽  
Vol 26 (20) ◽  
pp. 6095
Author(s):  
Magdalena Jakubczyk ◽  
Slawomir Michalkiewicz ◽  
Agata Skorupa ◽  
Daria Slefarska
Keyword(s):  
Electrode Materials ◽  
Supporting Electrolyte ◽  
Sodium Perchlorate ◽  
Total Content ◽  
Standard Addition ◽  
Differential Pulse ◽  
Voltammetric Determination ◽  
Pulse Voltammetry ◽  
Good Agreement

Thymol and carvacrol—the components of herbal spices—are known for their broad biological activity as antimicrobials and antioxidants. For this reason, it is important to develop new methods for their determination in plant material. A simple, rapid, and sensitive method for determination of total content of these analytes in herbal spices using differential pulse voltammetry (DPV) has been developed. The basis of the research is the oxidation process of isopropylmethylphenols on a platinum microelectrode in glacial acetic acid containing acetonitrile (20%, v/v) and 0.1 mol L−1 sodium perchlorate as the supporting electrolyte. Linear voltammetric responses for thymol and carvacrol were obtained in a wide concentration range from 0.39–1105 and 0.47–640 µg mL−1, with a low detection limit of 0.04 and 0.05 µg mL−1, respectively. The analysis was performed using the multiple standard addition method. The results of the voltammetric determination are in good agreement with the data of the standard chromatographic method. To the best of our knowledge, this is the first presentation of an electrochemical procedure to determine these compounds in these environmental and electrode materials.

scholarly journals Determination of relative acidity scales for some dipolar aprotic solvents by coulometry using a hydrogen-palladium electrode

2008 ◽  
Vol 73 (8-9) ◽  
pp. 871-878 ◽  
Author(s):  
Radmila Dzudovic ◽  
Ljiljana Jaksic
Keyword(s):  
Perchloric Acid ◽  
Supporting Electrolyte ◽  
Sodium Perchlorate ◽  
Electrode Pair ◽  
Tetrabutylammonium Perchlorate ◽  
Palladium Electrode ◽  
The Difference ◽  
Acidity Scale ◽  
Relative Acidity

A coulometric-potentiometric procedure for the determination of relative acidity scales of acetone, methylethyl ketone, methyl-isobutyl ketone and propylene carbonate is described. The range of the relative acidity scale of a solvent was determined from the difference between the half-neutralization potential of perchloric acid and that of tetrabutylammonium hydroxide. The perchloric acid was generated in situ from a hydrogen-palladium electrode in presence of sodium perchlorate or tetrabutylammonium perchlorate as the supporting electrolyte. The electrode pairs glass-SCE and (H2/Pd)ind-SCE were applied for the measurement of the half-neutralization potentials of the acid and base. A wider range of relative acidity scale of the solvents was obtained with the glass-SCE electrode pair and tetrabutylammonium perchlorate as the supporting electrolyte.

Sign in / Sign up

Export Citation Format

Share Document