SVIBOR - Papers quoted in CC - project code: 1-07-025

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Papers quoted in Current Contents on project 1-07-025

Quoted papers: 12
Other papers: 4
Total: 16

Title: Potentiometric determination of mercury(II) and thiourea in strong acid solution using an ion-selective electrode with AgI-based membrane hydrophobised by PTFE

Authors:: Radić, Njegomir (39595); Komljenović, Josipa (119831)

Journal: Fresenius' Journal of Analitical Chemistry
ISSN: 0937-0633
Volume: 341
Year: 1991
Pages: from 592 to 596
Number of references: 18
Language: engleski
Summary: The potentiometric determination of mercury(II) and thiourea(TU) in strong acid solution (pH 0 - 1) by using an "all-solid-state" ion-selective electrode with (silver-sulfide 25%, AgI 25% and PTFE 50% m/m) - membrane is described. Thelinear response, 43 mV/pHg and 80 mV/pTU, has been obtained in the concentration range from 10 to under 0.01 mmol/L. By direct potentiometry at pH 0 mercury(II) can be determined in the presence of up to 1 mmol/L of iron(III). The change in potential in the tested concentration range of thiourea indicates the formation of Ag/TU = 0.7 at the exposed surface of the membrane. This stoichiometry is in good agreement with that calculated fromthe average Ag/TU ratio in the potentiometric titration. Theinvestigated electrode can be used as a good sensor for mercury(II) and thiourea in strong acid media and a wide variety of practical analytical systems.
Keywords: Mercury(II), thiourea, strong acid solution, potentiometric determination, iodide ion-selective electrode

Title: Potentiometric determination of thiourea by using ion-selective electrode with AgI-based membrane hydrophobised with PTFE

Authors:: Komljenović, Josipa (119831); Radić, Njegomir (39595)

Journal: Acta Pharm. Jugosl.
ISSN: 1330-0075
Volume: 41
Year: 1991
Pages: from 41 to 46
Number of references: 8
Language: engleski
Summary: Potentiometric determination of thiourea (TU) in strongly acid solution (pH=1) by using "all-solid-state" ion-selective electrode with (silver-sulfide 25%, AgI 25% and PTFE 50% m/m) -membrane is described. The utilized sensing electrode has been prepared in the laboratory. The equilibrium potentials observed during serial dilution or standard addition, under constant pH and ionic strength, are plotted against log c(TU). A linear response with a slope 80 mV/pTU has been obtained in the concentration range from 10 to 0.01 mmol/L. The change in the potential, in tested concentration range of thiourea, indicates Ag/TU=0.7 formation at the exposed surface of membrane. The maximum response time of the potentialcell with electrode was 1 min. even at low concentrations of thiourea. The electrode reached a steady-state potential (drift0.3 mV/min) within the time of experiments. In all experiments the potential drifts were parallel and relatively small.
Keywords: Thiourea, potentiometric method, iodide ion-selective electrode

Title: Potentiometric determination of an overall formation constant using an ion-selective membrane electrode

Authors:: Radić, Njegomir (39595); Komljenović, Josipa (119831)

Journal: Journal of Chemical Education
Number: 6
ISSN: 0021-9584
Volume: 70
Year: 1993
Pages: from 509 to 511
Number of references: 6
Language: engleski
Summary: The development and application of ion-selective membrane electrodes continues to be a rapidly growing area of analytical chemistry. However in the standard analytical chemistry text book little attention is given to this subject and there is a gap between the available teaching sources and the research literature. This experiment introduces the student to a potentiometric study of aluminium-fluoride complex formation in water / organic solvent mixtures, using a fluoride ion-selective electrode with an La(III)-fluoride membrane. The electrode is used for determination of free fluoride ions in solution. Based on the colected values of the potentiometric titration experiment, the overall formation constant for aluminium-fluoride complex in water/acetonitrile mixtures is determined.
Keywords: Aluminium-fluoride complex, overall formation constant, water + acetonitrile mixtures, fluoride ion-selective electrode

Title: Desing of a fluoride-selective electrode with internal contact based on a Cu(II) ion-selective electrode

Authors:: Radić, Njegomir (39595); Bralić, Marija (119816)

Journal: Microchemical Journal
ISSN: 0026-265
Volume: 48
Year: 1993
Pages: from 377 to 382
Number of references: 6
Language: engleski
Summary: The design of an electrode body that provides internal contact with a La(III)-fluoride membrane based on a Cu(II) ion-selective electrode is described. The assembled fluoride electrode was examined in terms of potential-concentration curve sand potential-time response. The behavior of the fluoride ion-selective electrode with the investigated internal contact was in good agreement with the commercial fluoride electrode.
Keywords: La(III)-fluoride membrane, internal contact, Cu(II) ion-selective electrode, fluoride ion-selective electrode

Title: Potentiometric determination of N-acetylcysteine based on its reduction action on Fe(III)

Authors:: Komljenović, Josipa (119831); Radić, Njegomir (39595)

Journal: Acta Pharmaceutica
Number: 2
ISSN: 1330-0075
Volume: 43
Year: 1993
Pages: from 99 to 106
Number of references: 15
Language: engleski
Summary: A simple potentiometric method for the determination of N-acetylcysteine (NAC) is based on its reduction action on Fe(III) in acidic fluoride solution, pH 2. The method is described as an equilibrium method and kinetic method. The recorded potential value of the cell with fluoride ion-selective electrode or the calculated average rate are found to be linear with NAC concentration in solution. Good linearity is achieved in the range of NAC concentration from 0.2 mmol/L to 1.5 mmol/L. The kinetic method is proposed as the procedure of choice for the determination of NAC in pure substances or in pharmaceutical formulations, with relative standard deviation from 0.51 to 2.17%.
Keywords: N-acetylcysteine, potentiometric method, fluoride ion-selective electrode

Title: Kinetic-potentiometric determination of Fe(III) using a fluoride ion-selective electrode

Authors:: Radić, Njegomir (39595); Komljenović, Josipa (119831)

Journal: Croatica Chemica Acta
Number: 4
ISSN: 0011-1643
Volume: 64
Year: 1991
Pages: from 679 to 687
Number of references: 9
Language: engleski
Summary: A kinetic-potentiometric method is described for the determination of Fe(III), based on monitoring of the formation of Fe(III)-monofluoride in acid solution, using a fluoride ion-selective electrode. The influence of pH and fluoride concentration in cell solution on the kinetics of iron - fluoride reaction was studied. The initial rate of the complex formation reaction, or change in potential during fixed time interval (lminute), was used to construct calibration graphs. There is alinear relationship between the calculated initial rate or (E-E')-1 min. and concentration of iron in the cell solution. Good linearity (r=0.9979) was achieved in the range of iron concentration from 0.035 to 1.4 mmol/L.
Keywords: Iron(III), kinetic-potentiometric determination, fluoride ion-selective electrode

Title: Direct Potentiometric Measurements of Cysteine by Using Iodide-Selective Electrode

Authors:: Bralić, Marija (119816); Radić, Njegomir (39595)

Journal: Croatica Chemica Acta
ISSN: 0011-1643
Volume: 67
Year: 1994
Pages: from 543 to 551
Number of references: 20
Language: engleski
Summary: Potentiometric determination of cysteine (Cys) in aqueous solution by using iodide-selective electrode with (Ag2S + AgI) membrane is described. The analytical behaviour of this electrode is discussed in terms of the potential vs. concentration curve, potential vs. pH curve, and potential-time response. The equilibrium potentials observed during serial dilution or standard addition, under constant pH and ionic strenght, are plotted against log c(Cys). The linear response with a slope 58 mV šp(Cys)ć-1 has been obtained in the concentration range from 3ž10-3 to under 10-5 M. The change in potential in the tested concentration range of Cys (also designated as RSH) indicates RSAg coating formation at the exposed membrane surface. On the basis of potentiometric experiments, the solubility product of RSAg precipitate has been determined. The calculated mean value was pKsp(RSAg) = 18,66+-0,08.
Keywords: Cysteine, potentiometric measurement, iodide ion-selective electrode

Title: Solid-state electrode with a Cu(I)-based membrane hydrophobised by PTFE for the measurement of copper(II) and iodide ions

Authors:: Radić, Njegomir (39595); Papa, Miljenko

Journal: Fresenius' Journal of Analitical Chemistry
ISSN: 0937-0633
Volume: 351
Year: 1995
Pages: from 599 to 603
Number of references: 14
Language: engleski
Summary: The preparation of CuI + Ag2S and Cu2ŠHgI4Ć + Ag2S membrane hydrophobised by PTFE is described. The pressed membranes mounted in a multi-purpouse "all-solid-state" electrode body have been examined as electrochemical sensors for copper(II) and iodine ions. For the electrode with (CuI + Ag2S + PTFE)-membrane experimental slopes of 29 mV(pCu)-1 and 62 mV(pI)-1 were obtained, in good agreement with the theoretical values. For practical measurement in solutions where both copper(II) and iodine ions can be present, the investigated electrode offers certain advantages in comparasion with a comercial Cu-ISE.
Keywords: Copper, iodide, potentiometric measurement, Cu(I)-based membrane electrode

Title: Design and properties of flow-through electrode with AgI-based membrane hydrophobised by PTFE; application to flow-injection determination of thiourea

Authors:: Komljenović, Josipa (119831); Radić, Njegomir (39595)

Journal: Sensors and Actuators B
ISSN: 0925-4005
Volume: 24
Year: 1995
Pages: from 312 to 316
Number of references: 8
Language: engleski
Summary: A multi-purpose solid-state iodide-selective electrode is constructed as a compact tubular sensor; the sensing hole has 2,0 mm i.d. and 1,2 mm length. The behaviour, suitability and incorporation of the tubular electrode into the conduit of a flow-injection system are described. Application of the tubular electrode is exemplified by the determination of thiourea in 0,1 M HClO4 as supporting electrolyte by using of a flow-injection system. A rectilinear calibration graph is obtained by plotting the peak hight versus concentration of thiourea. The detection limit is 0,02 mM under optimized flow conditions (1,2 mL/min; 0,2 mL samples, 10-5 M silver ions in the carrier stream).
Keywords: Flow-injection analysis, membrane electrode, thiourea

Title: Electroanalytical Study of Aluminium Fluoride Complexation in 2-Propanol-Water Mixtures

Authors:: Radić, Njegomir (39595); Papa, Miljenko

Journal: Analytical Sciences
ISSN: 0910-6340
Volume: 11
Year: 1995
Pages: from 425 to 429
Number of references: 12
Language: engleski
Summary: Theoretical approaches to aluminium-ion by two potentiometric methods (potentiometric titration and analyte subtraction potentiometry) are discussed. The computed theoretical titration curves show that the equivalence point is signaled by a sufficiently large change in the potential only in media where aluminium forms a hexafluoride complex; the overall formation constants á(AlF6-3)>=10+28. On the basic of potentiometric titration and zhe known subtraction experiments in 2-propanol + water, buffered with acetate buffer (pH 5), the overall conditional constants (á') were calculated. The calculated average á'-values are 10+33, depending of the vol% of organic solvent, 50% and 67%. In the mixtures having a vol% of organic solvent of 50% or 67%, both metods can be applied for the determination of aluminium, via AlF6-3 complex formation, in the concentration range from 10-4 to 10-3 M.
Keywords: Potentiometry, fluoride-electrode, aluminium, nonaqueous media

Title: Fluoride-Selective Electrode with Internal Redox Reference Electrode

Authors:: Radić, Njegomir (39595); Bralić, Marija (119816)

Journal: Microchemica Acta
ISSN: 0026-3672
Volume: 118
Year: 1995
Pages: from 221 to 227
Number of references: 11
Language: engleski
Summary: The potential response of a symmetrical configuration in which the LaF3-membrane is placed between two solutions is discussed. The electrode body provides contact with the inner surface of the fluoride membrane, with solution containing Fe(CN)6-3 / Fe(CN)6-4 redox couple and Pt wire as internal reference electrode. The electrode was examined in terms of potential-concentration curves and potential-time response and shown to behave similarly to the commercial Orion fluoride electrode. The advantage of the proposed redox reference system is that the electrode has minimal drift immediately after assembly. 3 1
Keywords: Fluoride ion-selective electrode, LaF3-membrane, internal redox contact

Title: "Programmable" Selective Inexpesive Potentiometric Detector for Flow Injection Analysis. Potassium Determination with a Nafion Membrane Modifed Electrode

Authors:: Akmal, N; Lunsford, S.K; Galal, A; Karagozler, A.E; Mark, H.B; Radić, Njegomir (39595)

Journal: Croatica Chemica Acta
ISSN: 0011-1643
Volume: 68
Year: 1995
Pages: from 403 to 407
Number of references: 17
Language: engleski
Summary: The study of nafion membrane (ISE membrane) for the inexpensive potentiometric detection of potassium ion in a flow injection system is reported. The nafion membrane doped with potassium ion showed that excelent selectivity could be achieved for various cations, except for Rb+, and some interference for Cs+. A linear potential response of from 10-2 to 10-6 M for the potassium ion was obtained with a detection limit of about 5ž10-6 M. This approach can be employed for constructing a poetntiometric detector for virtually any cation (soluble at basic pH values) by simply changing the electrode pretreatment (or doping solution).
Keywords: Potassium, potentiometric determination, flow-injection analysis, nafion-membrane


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