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Akiharu Hioki - One of the best experts on this subject based on the ideXlab platform.
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reliability in standardization of sodium thiosulfate with potassium dichromate
Microchemical Journal, 2015Co-Authors: Toshiaki Asakai, Akiharu HiokiAbstract:Abstract Sodium thiosulfate is often standardized with potassium dichromate. In the standardization, iodine (triiodide) liberated by potassium dichromate in an acidic potassium iodide solution is titrated with a sodium thiosulfate solution. The iodine liberation process significantly affects the Titration results. In the present study, the accuracy of the liberation process was examined by assaying potassium dichromate through two different paths: assaying directly by Coulometric Titration with electrogenerated Fe(II), and assaying by gravimetric Titration through the iodine liberation reaction with a sodium thiosulfate solution of which concentration was standardized by Coulometric Titration with electrogenerated iodine. The accuracy of the standardization of a sodium thiosulfate solution by potassium dichromate was discussed from the apparent assays of potassium dichromate under different measurement conditions.
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Certified reference material for ammonium ions in high-purity ammonium chloride: Influence of pH on Coulometric Titration of ammonium ions with electrogenerated hypobromite
Microchemical Journal, 2014Co-Authors: Toshiaki Asakai, Tsutomu Miura, Toshihiro Suzuki, Akiharu HiokiAbstract:Abstract No report has been published concerning reference materials of ammonium chloride in which ammonium ions were accurately determined, though ammonium chloride is widely used as a standard of ammonium ions. In the present paper, accuracy of the Coulometric Titration of ammonium ions with electrogenerated hypobromite was studied. The authors found that the pH of electrolyte solution significantly affected the accuracy of the assay of ammonium ions. Lower assays were obtained at pH more than 8.5 or less than 8.0: much higher pH values led to evaporation of ammonia and much lower pH ones led to insufficient hypobromite generation or insufficient conditional equilibrium constant of the reaction between ammonium ions and hypobromite. Ammonium ions in ammonium chloride were certified by Coulometric Titration under an appropriate condition, and chloride ions in it were also certified by gravimetric Titration based on standard sodium chloride. The first certified reference material with ammonium assay was developed which enabled more accurate ammonium determination than that before.
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Assay of high-purity sodium oxalate traceable to the international system of units by Coulometric Titration and gravimetric Titration
Microchemical Journal, 2013Co-Authors: Toshiaki Asakai, Akiharu HiokiAbstract:Abstract Sodium oxalate is one of the key reference materials in volumetric analysis. This material and its solution are widely used as a reducing agent and as a standard to standardize oxidizing agents such as potassium permanganate; nevertheless, no certified reference material has been available until recently. The authors challenged purity assay of sodium oxalate basically with Ce(IV) which could accurately be standardized by Coulometric Titration. This paper describes the accurate determination of sodium oxalate through three different paths: gravimetric Titration with Ce(IV) standardized by Coulometric Titration, gravimetric back Titration using excess Ce(IV) and titrant thiosulfate both of which are standardized by Coulometric Titrations, and gravimetric back Titration using excess Ce(IV) and titrant Fe(II) both of which are standardized by Coulometric Titration and gravimetric Titration, respectively. Two kinds of back Titrations of excess Ce(IV) mentioned above were carried out to completely proceed with the reaction between oxalate and Ce(IV). The comprehensive evaluation of the uncertainties for sodium oxalate assay was carried out, resulting in the significant improvement of accuracy of oxalate determination. Finally, sodium oxalate whose purity was traceable to the SI was developed as a certified reference material.
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evaluation of the stability of iron ii solutions by precise Coulometric Titration with electrogenerated cerium iv
Analytical Sciences, 2012Co-Authors: Toshiaki Asakai, Akiharu HiokiAbstract:An iron(II) solution is often used as a reducing agent in titrimetry and standardized with cerium(IV) or potassium dichromate. Such an iron(II) standard solution is needed for not only titrimetric analyses, but also instrumental ones. Iron(II) is unstable even in a highly acidic solution, mainly due to air-oxidation; therefore, its standardization is required before use. In the present study, the concentration of an iron(II) solution was accurately determined by Coulometric Titration with electrogenerated cerium(IV), and also by gravimetric Titration with a standard potassium dichromate; new useful information concerning the stability of iron(II) solutions in aqueous sulfuric acid was obtained. The current efficiency of the Coulometric Titration with electrogenerated cerium(IV) was not very high; however, it was found that the Titration efficiency was sufficient to assay an iron(II) solution.
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Comparison of three electrochemical end-point detection methods to assay potassium dichromate by Coulometric Titration
Accreditation and Quality Assurance, 2012Co-Authors: Toshiaki Asakai, Akiharu HiokiAbstract:Coulometric Titrations with three electrochemical end-point detection methods were performed to assay potassium dichromate as a standard for oxidation–reduction Titration. The assay as an oxidizing agent was carried out with ferrous ions produced by electrolytically reducing ferric ions. Three end-point detection methods were employed and compared with each other: constant potential amperometry, potentiometry, and constant voltage biamperometry (a dead-stop method). The last one was found to provide high accuracy in the Coulometric Titration of potassium dichromate. Solution form samples were also measured to confirm the possible existence of chromium(III) in potassium dichromate by both Coulometric Titration and ion-exchange chromatography with inductively coupled plasma time-of-flight mass spectrometry.
Toshiaki Asakai - One of the best experts on this subject based on the ideXlab platform.
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reliability in standardization of sodium thiosulfate with potassium dichromate
Microchemical Journal, 2015Co-Authors: Toshiaki Asakai, Akiharu HiokiAbstract:Abstract Sodium thiosulfate is often standardized with potassium dichromate. In the standardization, iodine (triiodide) liberated by potassium dichromate in an acidic potassium iodide solution is titrated with a sodium thiosulfate solution. The iodine liberation process significantly affects the Titration results. In the present study, the accuracy of the liberation process was examined by assaying potassium dichromate through two different paths: assaying directly by Coulometric Titration with electrogenerated Fe(II), and assaying by gravimetric Titration through the iodine liberation reaction with a sodium thiosulfate solution of which concentration was standardized by Coulometric Titration with electrogenerated iodine. The accuracy of the standardization of a sodium thiosulfate solution by potassium dichromate was discussed from the apparent assays of potassium dichromate under different measurement conditions.
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Certified reference material for ammonium ions in high-purity ammonium chloride: Influence of pH on Coulometric Titration of ammonium ions with electrogenerated hypobromite
Microchemical Journal, 2014Co-Authors: Toshiaki Asakai, Tsutomu Miura, Toshihiro Suzuki, Akiharu HiokiAbstract:Abstract No report has been published concerning reference materials of ammonium chloride in which ammonium ions were accurately determined, though ammonium chloride is widely used as a standard of ammonium ions. In the present paper, accuracy of the Coulometric Titration of ammonium ions with electrogenerated hypobromite was studied. The authors found that the pH of electrolyte solution significantly affected the accuracy of the assay of ammonium ions. Lower assays were obtained at pH more than 8.5 or less than 8.0: much higher pH values led to evaporation of ammonia and much lower pH ones led to insufficient hypobromite generation or insufficient conditional equilibrium constant of the reaction between ammonium ions and hypobromite. Ammonium ions in ammonium chloride were certified by Coulometric Titration under an appropriate condition, and chloride ions in it were also certified by gravimetric Titration based on standard sodium chloride. The first certified reference material with ammonium assay was developed which enabled more accurate ammonium determination than that before.
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Assay of high-purity sodium oxalate traceable to the international system of units by Coulometric Titration and gravimetric Titration
Microchemical Journal, 2013Co-Authors: Toshiaki Asakai, Akiharu HiokiAbstract:Abstract Sodium oxalate is one of the key reference materials in volumetric analysis. This material and its solution are widely used as a reducing agent and as a standard to standardize oxidizing agents such as potassium permanganate; nevertheless, no certified reference material has been available until recently. The authors challenged purity assay of sodium oxalate basically with Ce(IV) which could accurately be standardized by Coulometric Titration. This paper describes the accurate determination of sodium oxalate through three different paths: gravimetric Titration with Ce(IV) standardized by Coulometric Titration, gravimetric back Titration using excess Ce(IV) and titrant thiosulfate both of which are standardized by Coulometric Titrations, and gravimetric back Titration using excess Ce(IV) and titrant Fe(II) both of which are standardized by Coulometric Titration and gravimetric Titration, respectively. Two kinds of back Titrations of excess Ce(IV) mentioned above were carried out to completely proceed with the reaction between oxalate and Ce(IV). The comprehensive evaluation of the uncertainties for sodium oxalate assay was carried out, resulting in the significant improvement of accuracy of oxalate determination. Finally, sodium oxalate whose purity was traceable to the SI was developed as a certified reference material.
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evaluation of the stability of iron ii solutions by precise Coulometric Titration with electrogenerated cerium iv
Analytical Sciences, 2012Co-Authors: Toshiaki Asakai, Akiharu HiokiAbstract:An iron(II) solution is often used as a reducing agent in titrimetry and standardized with cerium(IV) or potassium dichromate. Such an iron(II) standard solution is needed for not only titrimetric analyses, but also instrumental ones. Iron(II) is unstable even in a highly acidic solution, mainly due to air-oxidation; therefore, its standardization is required before use. In the present study, the concentration of an iron(II) solution was accurately determined by Coulometric Titration with electrogenerated cerium(IV), and also by gravimetric Titration with a standard potassium dichromate; new useful information concerning the stability of iron(II) solutions in aqueous sulfuric acid was obtained. The current efficiency of the Coulometric Titration with electrogenerated cerium(IV) was not very high; however, it was found that the Titration efficiency was sufficient to assay an iron(II) solution.
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Comparison of three electrochemical end-point detection methods to assay potassium dichromate by Coulometric Titration
Accreditation and Quality Assurance, 2012Co-Authors: Toshiaki Asakai, Akiharu HiokiAbstract:Coulometric Titrations with three electrochemical end-point detection methods were performed to assay potassium dichromate as a standard for oxidation–reduction Titration. The assay as an oxidizing agent was carried out with ferrous ions produced by electrolytically reducing ferric ions. Three end-point detection methods were employed and compared with each other: constant potential amperometry, potentiometry, and constant voltage biamperometry (a dead-stop method). The last one was found to provide high accuracy in the Coulometric Titration of potassium dichromate. Solution form samples were also measured to confirm the possible existence of chromium(III) in potassium dichromate by both Coulometric Titration and ion-exchange chromatography with inductively coupled plasma time-of-flight mass spectrometry.
M H R Lankhorst - One of the best experts on this subject based on the ideXlab platform.
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high temperature Coulometric Titration of la1 xsrxcoo3 δ evidence for the effect of electronic band structure on nonstoichiometry behavior
Journal of Solid State Chemistry, 1997Co-Authors: M H R Lankhorst, Henny J M Bouwmeester, H VerweijAbstract:The equilibrium oxygen chemical potential and the partial energy and entropy of O2in perovskites La1−xSrxCoO3−δwere measured as a function ofδandxby high-temperature oxygen Coulometric Titration. An almost linear decrease in the oxygen chemical potential is observed with increasing net electron concentration 2δ−x. The observed behavior is interpreted to reflect the corresponding increase in the Fermi level on filling up states in a broad electron band with electrons induced by vacancy formation or reducing the Sr-dopant level. The results enable calculation of the apparent density of states at the Fermi level. For low values ofδand high temperatures, the oxygen vacancies in La1−xSrxCoO3−δare randomly distributed among equivalent oxygen sites. By increasingδor by lowering the temperature, additional ionic contributions to the partial energy and entropy arise, but these cancel in the chemical potential of oxygen vacancies. These results are possibly due to ordering of oxygen vacancies into microdomains
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thermodynamic quantities and defect structure of la0 6sr0 4co1 yfeyo3 δ y 0 0 6 from high temperature Coulometric Titration experiments
Journal of Solid State Chemistry, 1997Co-Authors: M H R Lankhorst, J Ten E ElshofAbstract:The partial energies and entropies of O2in perovskite-type oxides La0.6Sr0.4Co1−yFeyO3−δ(y=0, 0.1, 0.25, 0.4, 0.6) were determined as a function of nonstoichiometryδby Coulometric Titration of oxygen in the temperature range 650–950°C. An absolute reference value ofδwas obtained by thermogravimetry in air. The nonstoichiometry at a given oxygen pressure and temperature decreases with iron contenty. At low nonstoichiometries the oxygen chemical potential decreases withδ. The observed behavior can be interpreted by assuming random distribution of oxygen vacancies, an electronic structure with both localized donor states on Fe, and a partially filled itinerant electron band, of which the density of states at the Fermi level scales with the Co content. The energy of the Fe states is close to the energy at the Fermi level in the conduction band. The observed trends of the thermodynamic quantities can be interpreted in terms of the itinerant electron model only when the iron content is small. At high values ofδthe chemical potential of O2becomes constant, indicating partial decomposition of the perovskite phase. The maximum value ofδat which the compositions are single-phase increases with temperature.
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determination of oxygen nonstoichiometry and diffusivity in mixed conducting oxides by oxygen Coulometric Titration ii oxygen nonstoichiometry and defect model for la0 8sr0 2coo3 delta
Journal of The Electrochemical Society, 1997Co-Authors: M H R Lankhorst, Henricus J M BouwmeesterAbstract:The oxygen nonstoichiometry of La0.8Sr0.2CoO3-delta has been determined as a function of oxygen partial pressure and temperature using a high-temperature Coulometric Titration cell. For each measured value of the oxygen chemical potential, the oxygen nonstoichiometry is found to be nearly independent of temperature. The equilibrium partial energy and entropy associated with oxygen incorporation have been determined as a function of oxygen nonstoichiometry and temperature. The results are interpreted in terms of a model in which it is assumed that conduction electrons, created during vacancy formation, gradually fill electron states in a wide electron band. A new relation between vacancy concentration, temperature, and oxygen partial pressure has been formulated which does not have the familiar appearance of a mass action type of equation.
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determination of oxygen nonstoichiometry and diffusivity in mixed conducting oxides by oxygen Coulometric Titration i chemical diffusion in la0 8sr0 2coo3 δ
Journal of The Electrochemical Society, 1997Co-Authors: M H R Lankhorst, Henny J M BouwmeesterAbstract:Oxygen Coulometric Titration has been applied to measure chemical diffusion in La0.8Sr0.2CoO3-δ between 700 and 1000°C. The transient current response to a potentiostatic step has been transformed from the time domain to the frequency domain. The equivalent circuit used to fit the resulting impedance data contains the element that describes the finite-length diffusion of oxygen into the sample specimen. Other elements included are the gas-phase capacitance and the sum of the gas-phase diffusion resistance and that associated with the limited surface exchange kinetics of the sample. The chemical diffusion coefficient of perovskite La0.8Sr0.2CoO3-δ has been determined as a function of temperature and oxygen partial pressure. Its value can be represented by ~D (cm2/s) = 5.91 x exp [(-135 kJ/mol)/RT], and turns out to be practically independent of oxygen partial pressure in the range 10-2 - 0.209 bar.
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use of the rigid band formalism to interpret the relationship between o chemical potential and electron concentration in la1 xsrxcoo3 δ
Physical Review Letters, 1996Co-Authors: M H R Lankhorst, Henricus J M Bouwmeester, H VerweijAbstract:The equilibrium oxygen chemical potential of mixed oxygen ion and electron conducting perovskites La1-xSrxCoO3-δ was measured as a function of δ and x by high temperature oxygen Coulometric Titration. An almost linear decrease in the chemical potential is observed with increasing net electron concentration. The observed behavior is interpreted to reflect the corresponding change in the Fermi level upon gradually filling up states in a broad electron band with electrons induced by vacancy formation and Sr doping. Assuming a rigid band formalism, an apparent density of states at the Fermi level was calculated, the value of which is in good agreement with that obtained from XPS.
Tatsuhiko Tanaka - One of the best experts on this subject based on the ideXlab platform.
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Coulometric Titration of Urea with Electrogenerated Hypobromite
Analytical Sciences, 2013Co-Authors: Jun Kato, Takuma Koseki, Yukie Aoki, Ayako Yamada, Tatsuhiko TanakaAbstract:A definitive method is described for the indirect assay of several tens of milligrams of urea by Coulometric Titration. Urea was decomposed in concentrated sulfuric acid using a Kjeldahl flask. Subsequently, the formed ammonium ion was titrated with electrogenerated hypobromite ion in a sodium bromide-sodium tetraborate medium of pH 8.6, with amperometric end-point detection. Parameters affecting the pretreatment procedure were evaluated. The optimized conditions included the heating of 2 g of urea at around 300°C for 2 h with 10 cm(3) of sulfuric acid. Under the proposed conditions, the assay value with expanded uncertainty (k = 2), 99.870 ± 0.026%, agreed well with the certified value of NIST SRM 912a urea, 99.9 ± 0.1%.
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Precise Coulometric Titration of sodium thiosulfate and development of potassium iodate as a redox standard
Talanta, 2007Co-Authors: Toshiaki Asakai, Mariko Murayama, Tatsuhiko TanakaAbstract:Abstract In this paper, we determine the effective purity of potassium iodate as a redox standard with a certified value linked to the international system of units (SI units). Concentration measurement of sodium thiosulfate solution was performed by precise Coulometric Titration with electrogenerated iodine, and an assay of potassium iodate was carried out by gravimetric Titration based on the reductometric factor of sodium thiosulfate assigned by coulometry. The accuracy of the Coulometric Titration method was evaluated by examining the current efficiency of iodine electrogeneration, stability of sodium thiosulfate solutions and dependence on the amount of sodium thiosulfate solution used. The measurement procedure for gravimetric Titration of potassium iodate with sodium thiosulfate was validated based on determination of a reference material of known purity (potassium dichromate determined by coulometry with electrogenerated ferrous ions) using the same gravimetric method. Solutions of 0.2 and 0.5 mol/L sodium thiosulfate were stable over 17 days without stabilizer. Investigation of the dependency of Titration results on the amount of sodium thiosulfate solution used showed no significant effects, no evidence of diffusion of the sample, and no effect of contamination appearing during the experiment. Precise Coulometric Titration of sodium thiosulfate achieved a relative standard deviation of less than 0.005% under repeating conditions (six measurements). For gravimetric Titration, the results obtained for the effective purity of potassium dichromate were sufficiently close to its certified value to allow confirmation of the validity of the gravimetric Titration was confirmed. The relative standard deviation of gravimetric Titration for potassium iodate was less than 0.011% (nine measurements), and a redox standard with a certified value linked to SI units was developed.
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evaluation of certified reference materials for oxidation reduction Titration by precise Coulometric Titration and volumetric analysis
Analytica Chimica Acta, 2006Co-Authors: Toshiaki Asakai, Mariko Murayama, Yoshihiro Kakihara, Yasuharu Kozuka, Sadao Hossaka, Tatsuhiko TanakaAbstract:Abstract The accuracy and uncertainty of Coulometric Titration of Japanese certified reference materials (CRMs) for oxidation–reduction Titration were examined in this study. The results for potassium dichromate, sodium oxalate, and potassium iodate are presented. Potassium dichromate was directly determined by Coulometric Titration, and sodium oxalate and potassium iodate were determined by volumetric analysis using potassium dichromate assigned by coulometry. The uncertainty of the method was investigated by examining the dependency on the sample size and on the electrolysis current. Changes in the Titration parameters did not result in any significant effects on the Titration results. The Coulometric system used primarily consists of a constant current source, timer, switching circuit, indicator unit, and voltmeter. They were controlled using the coulometry software by a PC/AT compatible computer. A highly automated Coulometric system achieves repeatabilities of less than one part in 30,000 ( k = 2) and uncertainties of less than one part in 15,000 ( k = 2). In addition, using volumetric method, SI units traceable sodium oxalate and potassium iodate (purity standards for redox reaction) CRMs were developed. Reference materials for volumetric analysis are the most basic substances used in analytical chemistry. These materials are analyzed by several analytical methods and are produced globally; however, their purities have not been compared at the international level. Therefore, the relationship between the purity and reliability of these materials has not yet been established. In this paper, we determine the relationship between these parameters by titrating each material obtained from different laboratories.
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Coulometric Titration of d glucose using its enzymatic oxidation
Analytical Sciences, 2001Co-Authors: Tatsuhiko Tanaka, Eiko Shutto, Toshiaki Mizoguchi, Kikuko FukushimaAbstract:A definitive method is described for the indirect assay of milligram quantities of D(+)-glucose by Coulometric Titration. D(+)-Glucose was aerobically oxidized by glucose oxidase in an acetate buffer solution (pH 5.1). Subsequently, the enzymatically formed hydrogen peroxide was titrated Coulometrically with electrogenerated hypobromite in sodium bromide-sodium tetraborate medium of pH 8.6, with biamperometric end-point detection. Parameters affecting the enzymatically catalyzed oxidation and Coulometric Titration were evaluated. The optimized conditions for the oxidation of up to 20 mg of D(+)-glucose include the addition of 4500 U of glucose oxidase and stirring over a 10-min interval at 25°C. Under proposed conditions, the assay values of several commercial D(+)-glucose reagents were somewhat lower than the guaranteed minimum values, with RSDs (n = 5) of 0.071 - 0.106%.
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Coulometric Titration of sodium oxalate with electrogenerated lead ii
Analytical Sciences, 1993Co-Authors: Tatsuhiko Tanaka, Atsushi Takahashi, Shiduo Kobayashi, Atsushi MizuikeAbstract:Lead(II) was generated from an amalgamated lead anode in solutions containing 0.2-1M potassium nitrate and 30% ethanol with a 100% current efficiency over a wide range of current densities. Sodium oxalate reference materials, dried at 200°C for 1h, were titrated Coulometrically with electrogenerated Lead(II), with a relative standard deviation of 0.012%. A sharp end point of the precipitation reaction was detected amperometrically with a dropping mercury electrode in the presence of ethanol in the electrolyte. The results were in good agreement with the certified values based on a comparison with primary standards for oxidation-reduction Titrations.
Ernest Beinrohr - One of the best experts on this subject based on the ideXlab platform.
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indirect determination of aluminum iii in water samples by in electrode Coulometric Titration
Microchemical Journal, 2021Co-Authors: Jakub Masac, Ernest Beinrohr, Jan Lovic, Frantisek CachoAbstract:Abstract A new procedure has been developed for indirect determination of aluminium(III) in water through in-electrode Coulometric Titration in a porous reticulated vitreous carbon electrode. It was determined through different aluminium fluoride and ferric fluoride complex stabilities. The ferric fluoride complex thereby formed was decomposed with Al(III) from the sample and an aliquot of the released Fe(III) was determined electrochemically. It was measured with an EcaFlow GLP 150 electrochemical flow analyser, while 0.2 mol L−1 sodium chloride solution was used as the electrolyte to flush the system. Calibration solutions and samples were modified in a mixed solution medium of 0.2 mol L−1 NaCl + 10 mg L−1F(I-) + 10 mg L−1Fe(III). All working parameters for electrochemical determination were optimised. The detection limit and precision were found to be 0.02 mg L−1 and 1.9% respectively. The linear concentration range was 0.05 – 8.5 mg L−1 of aluminium. After having been complexed with sodium cyanide, the iron’s interference effect was suppressed by removing it with an ion-exchange resin. Among the other influences studied, only the interference from thorium, zirconium and cerium was significant. The method was applied for the analysis of various water samples. The results were in good agreement with data from high resolution atomic absorption spectrometry.
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determination of nitrates in water samples by in electrode Coulometric Titration in copper coated porous vitreous carbon electrode
Electroanalysis, 2015Co-Authors: Lukas Lauko, Katarina Lenghartova, Frantisek Cacho, Jana Sadecka, Ernest BeinrohrAbstract:Nitrate in water samples was determined by in-electrode Coulometric Titration in porous electrode made of vitreous carbon particles coated with copper. The sample was mixed with diluted sulfuric acid containing 1 mmol/L hydrochloric acid, the solution was filled into the cell and electrode and the nitrate ions were directly reduced by constant current to ammonium ions. The stoichiometry of the electrode reaction was found by Coulometric and photometric measurements. The detection limit and precision were found to be 0.2 mg/L and 1.7 %, respectively. The interfering effect of high chloride contents was eliminated by precipitating chlorides with silver sulfate. The method was applied for the analysis of various water samples and beverages. The results were in good agreement with data from isotachophoretic and photometric measurements.
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determination of nitrites in water by in electrode Coulometric Titration in reticulated vitreous carbon electrode
Acta Chimica Slovenica, 2015Co-Authors: Katarina Lenghartova, Lukas Lauko, Frantisek Cachob, Ernest BeinrohrAbstract:Nitrite in water samples was determined by in-electrode Coulometric Titration in a reticulated vitreous carbon (RVC) electrode of 100 ppi porosity. The sample was mixed with dilute sulphuric acid and sodium sulphate, filled into a flow cell with the porous electrode and nitrite was oxidised to nitrate by constant current of 5 µA at which the potential of the electrode was monitored. The limits of detection and quantification were found to be 0.4 and 1.2 µg/L, respectively. The repeatability and reproducibility were 2.2 % and 2.6 %, respectively. The bias at 100 µg/L were found to be 0.3 %. The duration of the measurement is 2-3 min depending on the nitrite concentration. There were few interferences only, neutral and cationic surfactants decreased and increased slightly the signal, respectively. Humic acids above 30 mg/L increased the signal by 10 %. Drinking and surface water samples were analysed and the results matched well those from the photometric method.
