The Experts below are selected from a list of 8742 Experts worldwide ranked by ideXlab platform
Khiena Z. Brainina - One of the best experts on this subject based on the ideXlab platform.
-
Contact hybrid Potentiometric Method for on-site and in situ estimation of the antioxidant activity of fruits and vegetables.
Food Chemistry, 2020Co-Authors: Khiena Z. Brainina, Aleksey V. Tarasov, Ekaterina Khamzina, Natalia Stozhko, Marina B. VidrevichAbstract:Abstract A new version of the hybrid Potentiometric Method (HPM) for evaluating the antioxidant activity (AOA) of fruits and vegetables, which we called contact (CHPM), is proposed. A screen-printed electrode pair coated by a membrane impregnated with a mediator serves as a sensor system. The potential shift, which is observed when the sensor system is exposed to the sample slice is used as a source of information. CHPM provides reproducible and correct results: relative standard deviation does not exceed 8.4% and recovery of model antioxidant at close to 100%. The AOA values of fruits and vegetables found by CHPM are in the range of 1–21 μmol-eq/g. Correlation between the AOA of slices and suspensions is found. The proposed CHPM can be used in on-site and in situ formats.
-
Potentiometric Method of plant microsuspensions antioxidant activity determination
Food Chemistry, 2019Co-Authors: Khiena Z. Brainina, Ekaterina Khamzina, Natalia Stozhko, Maria A Bukharinova, Marina B. VidrevichAbstract:This paper focuses on the development of a simple, fast and reliable technique of sample preparation to be employed as part of Potentiometric measurements of plant total antioxidant activity (AOA). Plant extracts and plant microsuspensions were analysed. The conditions for obtaining plant extracts were chosen: they exhibited the highest antioxidant activity at +80 °C and extraction time 20 min. A higher degree of dispersion of the analysed samples was accompanied by an increase in AOA of extracts and microsuspensions. The microsuspension enhanced effect results from the fact that antioxidants contained in both liquid and solid fractions are involved in the zone of a signal-generating reaction. The analysis of plant microsuspensions reduces the duration of AOA assessment. Comparison of the results of antioxidant activity of black and green tea microsuspensions with the results of the analysis of extracts prepared by a certified Method showed no difference.
-
noninvasive Potentiometric Method of determination of skin oxidant antioxidant activity
IEEE Sensors Journal, 2012Co-Authors: Khiena Z. Brainina, E L Gerasimova, L. G. Galperin, M. Y. KhodosAbstract:A noninvasive Potentiometric Method of determining skin oxidant/antioxidant activity is proposed that allows to measure, the shift of the potential of the mediator system applied to the skin in a mixture with a conductive gel. Direct correlation between the concentration of oxidants or antioxidants in the skin and related compounds, extracted from the skin to gel is proved mathematically. The possibility of using characteristics of skin OA/AOA as a criterion for assessing human health is discussed.
-
Noninvasive Potentiometric Method of Determination of Skin Oxidant/Antioxidant Activity
IEEE Sensors Journal, 2012Co-Authors: Khiena Z. Brainina, E L Gerasimova, L. G. Galperin, M. Y. KhodosAbstract:A noninvasive Potentiometric Method of determining skin oxidant/antioxidant activity is proposed that allows to measure, the shift of the potential of the mediator system applied to the skin in a mixture with a conductive gel. Direct correlation between the concentration of oxidants or antioxidants in the skin and related compounds, extracted from the skin to gel is proved mathematically. The possibility of using characteristics of skin OA/AOA as a criterion for assessing human health is discussed.
Zohreh Karimzadeh - One of the best experts on this subject based on the ideXlab platform.
-
thermodynamic investigation of kcl in the ternary kcl licl h2 o mixed electrolyte system based on Potentiometric Method
Calphad-computer Coupling of Phase Diagrams and Thermochemistry, 2007Co-Authors: Farzad Deyhimi, Rahman Salamatahangari, Zohreh KarimzadehAbstract:Abstract The results of a thermodynamic investigation of KCl salt in the ternary KCl+LiCl+H 2 O electrolyte system by Potentiometric Method are reported in this work. The experimental Potentiometric data were obtained from a galvanic cell by combining a solvent polymeric (PVC) potassium-selective membrane electrode (K + ISE), containing Valinomycin as ionophore, and an Ag/AgCl electrode. The measurements were performed, at similar constant ionic strengths, in different series of mixed salt solutions, each characterized by a fixed salt molal ratio r (where r = m 1 / m 2 = 0.1 , 0.2 , 1 , 5 , 10 , and m 1 , m 2 are the molalities of KCl and LiCl, respectively). The non-ideal behaviour of the system was described on the base of the Pitzer ion-interaction model for mixed salts, over the ionic strength ranging from 0.01 up to about 5 mol/kg, at 298.15 K. Based on the obtained Pitzer ion-interaction parameters, the osmotic coefficients, solvent activities, and excess Gibbs free energies were determined for these investigated ternary electrolyte systems.
-
TERNARY NaCl+LiCl+H2O MIXED ELECTROLYTE SYSTEM: DETERMINATION OF ACTIVITY COEFFICIENTS BASED ON Potentiometric Method
Chemical Engineering Communications, 2007Co-Authors: Farzad Deyhimi, Mojgan Sabzehzari, Zohreh KarimzadehAbstract:The mean activity coefficients for NaCl in a ternary electrolyte system were determined by the Potentiometric Method, at 25°C, using a solvent polymeric (PVC) sodium-selective membrane electrode (Na+ ISE), containing N,N′-dibenzyl-N,N′-diphenyl-1,2-phenylenedioxydiacetamide as ionophore, and combined with an Ag/AgCl electrode. The Potentiometric measurements were performed at the same ionic strengths in different series of mixed salt solutions, each characterized by a fixed salt molal ratio r (where r = m1/m2 = 1, 10, 50, 100). The nonideal behavior of the ternary NaCl(m1) + LiCl(m2) + H2O electrolyte system was described based on the Pitzer ion-interaction model for mixed salts over the ionic strength ranging from 0.01 up to about 4 mol/kg. Two- and three-particle Pitzer interaction parameters for a mixed electrolyte system were determined based on Potentiometric data, and the critical role of Potentiometric selectivity coefficient (K 12) of ISE as limiting factor in the Potentiometric measurements was a...
-
Thermodynamic investigation of KCl in the ternary KCl/LiCl/ H2 O mixed electrolyte system based on Potentiometric Method
Calphad, 2007Co-Authors: Farzad Deyhimi, Rahman Salamat-ahangari, Zohreh KarimzadehAbstract:Abstract The results of a thermodynamic investigation of KCl salt in the ternary KCl+LiCl+H 2 O electrolyte system by Potentiometric Method are reported in this work. The experimental Potentiometric data were obtained from a galvanic cell by combining a solvent polymeric (PVC) potassium-selective membrane electrode (K + ISE), containing Valinomycin as ionophore, and an Ag/AgCl electrode. The measurements were performed, at similar constant ionic strengths, in different series of mixed salt solutions, each characterized by a fixed salt molal ratio r (where r = m 1 / m 2 = 0.1 , 0.2 , 1 , 5 , 10 , and m 1 , m 2 are the molalities of KCl and LiCl, respectively). The non-ideal behaviour of the system was described on the base of the Pitzer ion-interaction model for mixed salts, over the ionic strength ranging from 0.01 up to about 5 mol/kg, at 298.15 K. Based on the obtained Pitzer ion-interaction parameters, the osmotic coefficients, solvent activities, and excess Gibbs free energies were determined for these investigated ternary electrolyte systems.
E L Gerasimova - One of the best experts on this subject based on the ideXlab platform.
-
new antiradical capacity assay with the use Potentiometric Method
Analytica Chimica Acta, 2019Co-Authors: A. V. Ivanova, E L Gerasimova, E R GazizullinaAbstract:Abstract For the first time, the dependence of a redox potential change during a reaction of peroxyl radical generation and their interaction with antioxidants was studied. A regular change of a potential is due to oxidation of an antioxidant by initiating peroxyl radicals accompanied by an electron transfer. An original direct Method for determining induction periods, inhibition coefficients and an antiradical capacity using the Potentiometric Method is proposed. Using the proposed approach the induction periods and the inhibition coefficients of various OH, NH, SH containing antioxidants were determined. The antiradical capacity of a herbal extract was studied. A high degree of correlation with a DPPH assay was obtained. RSD results obtained using the proposed approach do not exceed 7%.
-
Potentiometric Method for determination of kinetic characteristics of radical reactions in aqueous media
Russian Chemical Bulletin, 2017Co-Authors: A. V. Ivanova, E L Gerasimova, E R Gazizullina, A. G. Davletchurina, A. N. Kozitsina, O. T. KasaikinaAbstract:Kinetic features of the reactions of K4[Fe(CN)6] with radicals initiated by water-soluble azo-initiator 2,2′-azobis(2-amidinopropane) dihydrochloride (AAPH) at 37 °C were studied using the Potentiometric Method. Potassium ferrocyanide was shown to be a radical acceptor, whereas K3[Fe(CN)6] formed by the oxidation with the radicals in combination with K4[Fe(CN)6] is an electrochemical system, the study of which makes it possible to determine kinetic characteristics of radical reactions. The rate constants for the reactions of peroxide radicals RO2 · with K4[Fe(CN)6] were calculated.
-
Kinetics of the thermal decomposition of 2,2′-azobis(2-methylpropionamidine)dihydrochloride studied by the Potentiometric Method using metal complexes
Russian Chemical Bulletin, 2016Co-Authors: A. V. Ivanova, E L Gerasimova, E R Gazizullina, A. N. Kozitsina, A. I. MaternAbstract:A Potentiometric Method was proposed for the determination of rate constants for peroxyl radical generation using the reduced form of the metal in the complex. The kinetics of the thermal decomposition of 2,2′-azobis(2-methylpropionamidine)dihydrochloride was studied. The requirements for an electron donor (reactant) were formulated. The iron(ii) complex with EDTA, the iron(ii) complex with o-phenanthroline, and potassium hexacyanoferrate(ii) were used as reactants. The rate for peroxyl radical generation and the generation rate constant (the latter turned out to be (0.92±0.06)•10–6 s–1) were calculated. The studies were carried out for different temperatures and concentrations of the initiator and complex.
-
kinetics of the thermal decomposition of 2 2 azobis 2 methylpropionamidine dihydrochloride studied by the Potentiometric Method using metal complexes
Russian Chemical Bulletin, 2016Co-Authors: A. V. Ivanova, E L Gerasimova, E R Gazizullina, A. N. Kozitsina, A. I. MaternAbstract:A Potentiometric Method was proposed for the determination of rate constants for peroxyl radical generation using the reduced form of the metal in the complex. The kinetics of the thermal decomposition of 2,2′-azobis(2-methylpropionamidine)dihydrochloride was studied. The requirements for an electron donor (reactant) were formulated. The iron(ii) complex with EDTA, the iron(ii) complex with o-phenanthroline, and potassium hexacyanoferrate(ii) were used as reactants. The rate for peroxyl radical generation and the generation rate constant (the latter turned out to be (0.92±0.06)•10–6 s–1) were calculated. The studies were carried out for different temperatures and concentrations of the initiator and complex.
-
Potentiometric Method for Evaluating the Oxidant/Antioxidant Activity of Seminal and Follicular Fluids and Clinical Significance of this Parameter for Human Reproductive Function
The Open Chemical and Biomedical Methods Journal, 2012Co-Authors: Kh. Z. Brainina, E L Gerasimova, D. P. Varzakova, S. L. Balezin, I. G. Portnov, V. A. Makutina, E. V. TyrchaninovaAbstract:Potentiometric Method based on the sharp change of electrode potential for the ferricyanide/ferrocyanide mediator system after addition of the seminal or follicular fluid sample into the measuring electrochemical cell has been developed to enable the easy assessment of the oxidant/antioxidant status of these kind of biological fluids. Platinum screen printed electrode has been used as an indicator. Essential advantage of the proposed Method is simultaneous use of the both forms of the ferricyanide/ferrocyanide mediator system (oxidized and reduced ones) that allows estimating oxidant and antioxidant components of the seminal or follicular fluids samples which were obtained, respectively, from 99 male and 27 female subjects. Oxidant activity of seminal fluids has been observed in pathology conditions of reproductive system of male studied subjects and related with possible male infertility symptoms.
Farzad Deyhimi - One of the best experts on this subject based on the ideXlab platform.
-
thermodynamic investigation of kcl in the ternary kcl licl h2 o mixed electrolyte system based on Potentiometric Method
Calphad-computer Coupling of Phase Diagrams and Thermochemistry, 2007Co-Authors: Farzad Deyhimi, Rahman Salamatahangari, Zohreh KarimzadehAbstract:Abstract The results of a thermodynamic investigation of KCl salt in the ternary KCl+LiCl+H 2 O electrolyte system by Potentiometric Method are reported in this work. The experimental Potentiometric data were obtained from a galvanic cell by combining a solvent polymeric (PVC) potassium-selective membrane electrode (K + ISE), containing Valinomycin as ionophore, and an Ag/AgCl electrode. The measurements were performed, at similar constant ionic strengths, in different series of mixed salt solutions, each characterized by a fixed salt molal ratio r (where r = m 1 / m 2 = 0.1 , 0.2 , 1 , 5 , 10 , and m 1 , m 2 are the molalities of KCl and LiCl, respectively). The non-ideal behaviour of the system was described on the base of the Pitzer ion-interaction model for mixed salts, over the ionic strength ranging from 0.01 up to about 5 mol/kg, at 298.15 K. Based on the obtained Pitzer ion-interaction parameters, the osmotic coefficients, solvent activities, and excess Gibbs free energies were determined for these investigated ternary electrolyte systems.
-
TERNARY NaCl+LiCl+H2O MIXED ELECTROLYTE SYSTEM: DETERMINATION OF ACTIVITY COEFFICIENTS BASED ON Potentiometric Method
Chemical Engineering Communications, 2007Co-Authors: Farzad Deyhimi, Mojgan Sabzehzari, Zohreh KarimzadehAbstract:The mean activity coefficients for NaCl in a ternary electrolyte system were determined by the Potentiometric Method, at 25°C, using a solvent polymeric (PVC) sodium-selective membrane electrode (Na+ ISE), containing N,N′-dibenzyl-N,N′-diphenyl-1,2-phenylenedioxydiacetamide as ionophore, and combined with an Ag/AgCl electrode. The Potentiometric measurements were performed at the same ionic strengths in different series of mixed salt solutions, each characterized by a fixed salt molal ratio r (where r = m1/m2 = 1, 10, 50, 100). The nonideal behavior of the ternary NaCl(m1) + LiCl(m2) + H2O electrolyte system was described based on the Pitzer ion-interaction model for mixed salts over the ionic strength ranging from 0.01 up to about 4 mol/kg. Two- and three-particle Pitzer interaction parameters for a mixed electrolyte system were determined based on Potentiometric data, and the critical role of Potentiometric selectivity coefficient (K 12) of ISE as limiting factor in the Potentiometric measurements was a...
-
Thermodynamic investigation of KCl in the ternary KCl/LiCl/ H2 O mixed electrolyte system based on Potentiometric Method
Calphad, 2007Co-Authors: Farzad Deyhimi, Rahman Salamat-ahangari, Zohreh KarimzadehAbstract:Abstract The results of a thermodynamic investigation of KCl salt in the ternary KCl+LiCl+H 2 O electrolyte system by Potentiometric Method are reported in this work. The experimental Potentiometric data were obtained from a galvanic cell by combining a solvent polymeric (PVC) potassium-selective membrane electrode (K + ISE), containing Valinomycin as ionophore, and an Ag/AgCl electrode. The measurements were performed, at similar constant ionic strengths, in different series of mixed salt solutions, each characterized by a fixed salt molal ratio r (where r = m 1 / m 2 = 0.1 , 0.2 , 1 , 5 , 10 , and m 1 , m 2 are the molalities of KCl and LiCl, respectively). The non-ideal behaviour of the system was described on the base of the Pitzer ion-interaction model for mixed salts, over the ionic strength ranging from 0.01 up to about 5 mol/kg, at 298.15 K. Based on the obtained Pitzer ion-interaction parameters, the osmotic coefficients, solvent activities, and excess Gibbs free energies were determined for these investigated ternary electrolyte systems.
-
An initial-rate Potentiometric Method for the determination of uric acid using a fluoride ion-selective electrode
Talanta, 2003Co-Authors: Farzad Deyhimi, Rahman Salamat-ahangariAbstract:Abstract The principle of a general Potentiometric Method based on Emerson–Trinder reaction for the assay of various hydrogen peroxide generating systems is reported. Emerson–Trinder reaction, habitually employed as a spectrophotometric indicator reaction, is exploited in this Method as a Potentiometric indicator reaction. This Method is based on the detection of F − ions, liberated from the oxidation of a fluorophenol compound used as hydrogen-donor in Emerson–Trinder reaction, by a fluoride ion-selective electrode. The ability and usefulness of this Method are illustrated by an initial-rate Potentiometric determination of uric acid in aqueous and human serum samples, for which, initial-rate reaction progress curves, linear calibration curve, within-day precisions, upper and lower detection limits, and also its analytical recovery were reported.
Mohammad A. Bagherinia - One of the best experts on this subject based on the ideXlab platform.
-
Thermodynamic properties determination of aqueous mixtures of CaCl2 and Ca(NO3)2 by the Potentiometric Method at T = 298.15 ± 0.1 K
The Journal of Chemical Thermodynamics, 2015Co-Authors: Amir Rahimzadeh, Mohammad A. BagheriniaAbstract:Abstract The main goal of this work is to provide precise thermodynamic data about the ternary system (CaCl2 + Ca(NO3)2 + H2O), which may allow modeling its behavior. The Pitzer ion interaction model and Harned rule were used to illustrate the ternary electrolyte system. The activity coefficients were determined using a Potentiometric Method. The measurements were performed at T = 298.15 ± 0.1 K and at total ionic strengths from (0.0010 to 5.0000) mol · kg−1. Different series of molal salt ratios were r = m CaCl 2 m Ca ( NO 3 ) 2 = 1.00, 2.50, 5.00, 10.00 and 15.00. The PVC based calcium ion-selective electrode (Ca2+-ISE), and the Ag/AgCl electrode used in this work were prepared in our laboratory. The mixing Pitzer parameters ( θ ClNO 3 , Ψ CaClNO 3 ) were determined for this system. Then these parameters were used to calculate thermodynamic properties such as the osmotic coefficients ( ∅ ), the activity coefficients of Ca(NO3)2 in the mixture ( γ ± Ca ( NO 3 ) 2 ) and the excess Gibbs free energy (GE). The experimental results showed that both Pitzer model and Harned rule were suitable to be used satisfactorily to describe this system.
-
Determination and modeling of activity coefficients of cobalt chloride in the (water+ethanol) mixed solvent system by Potentiometric Method at 298.15K
Journal of Molecular Liquids, 2014Co-Authors: Mohammad A. Bagherinia, Mohammad PournaghdiAbstract:Abstract In this work, the thermodynamic properties of (CoCl2 + C2H5OH + H2O) system were investigated by Potentiometric Method and based on Pitzer ion interaction model. For this purpose, primarily the mean activity coefficients of CoCl2 in pure water and ethanol–water mixture solvent were determined using a galvanic cell without liquid junction potential of type: Co2 +-ISE|CoCl2 (m), C2H5OH (wt.%), H2O (100-wt.%) |Ag·AgCl. The measurements were performed at T = 298.15 K and at total ionic strengths from 0.001 to 6.000 mol·kg− 1 in various ethanol–water mixed solvent systems containing 0, 10, 20, 30, 40 and 50% mass fractions of ethanol. The mean activity coefficients measured were correlated with Pitzer ion interaction model and the Pitzer adjustable parameters were determined. Then these parameters were used to calculate the thermodynamics properties for under investigated system. The results showed that the Pitzer ion interaction model can satisfactory describe the investigated system. The modified three-characteristic-parameter correlation (TCPC) model was applied to correlate the experimental activity coefficient data for under investigation electrolyte system, too. The results showed that the modified TCPC model also was suitable in the case of the mixed solvent system.
-
Determination of thermodynamic properties of the ternary electrolyte system {CoCl2 + Co(NO3)2 + H2O} by the Potentiometric Method at T = 298.15
The Journal of Chemical Thermodynamics, 2013Co-Authors: Golam R. Vaghar, Mohammad A. Bagherinia, Azin AzarinezhadianAbstract:Abstract In this work, the Pitzer ion interaction model and Harned rule were used to illustrate the ternary electrolyte system {CoCl2 + Co(NO3)2 + H2O}. The activity coefficients were determined using a Potentiometric Method. The galvanic cell used had no liquid junction of type: Co2+-ISE|CoCl2 (mA), Co(NO3)2 (mB), H2O|Ag.AgCl. The measurements were performed at T = 298.15 K and at total ionic strengths from 0.001 to 6.000 mol · kg−1 for different series of salt ratios r = m CoCl 2 m Co ( NO 3 ) 2 = 1.00, 2.50, 5.00, 7.50, 10.00 and 15.00. The PVC based cobalt ion-selective electrode (Co2+-ISE), the PVC based nitrate ion-selective electrode (NO3−-ISE) and the Ag/AgCl electrode used in this work were prepared in our laboratory and showed a reasonably good Nernst response. The experimental results showed that both Pitzer model and Harned rule were suitable to be used satisfactorily to describe this ternary system.
-
determination of thermodynamic properties of aqueous mixtures of mgcl2 and mg no3 2 by the Potentiometric Method at t 298 15
Fluid Phase Equilibria, 2011Co-Authors: Mohammad Pournaghdy, Masoud Giahi, Mohammad A. Bagherinia, M. Monajjemi, Hossein Aghaie, Mehran AghaieAbstract:Abstract In this research, thermodynamic properties of the ternary electrolyte system (MgCl2 + Mg(NO3)2 + H2O) were investigated using a Potentiometric Method. The galvanic cell used had no liquid junction of type: Mg-ISE|MgCl2 (mA), Mg(NO3)2 (mB), H2O|Ag/AgCl. The measurements were performed at T = 298.15 K and at total ionic strengths from 0.001 to 8.000 mol/kg for different series of salt ratios r = m MgCl 2 / m Mg ( N O 3 ) 2 =1.00, 2.50, 5.00, 7.50, 10.00 and 15.00. The PVC based magnesium ion-selective electrode (Mg-ISE) and the Ag/AgCl electrode used in this work were prepared in our laboratory and showed a reasonably good Nernst response. The Pitzer ion interaction model and Harned rule were used to illustrate the ternary electrolyte system investigated. The experimental results showed that both Pitzer model and Harned rule were suitable to be used satisfactorily to describe this ternary system.
-
Determination of thermodynamic properties of aqueous mixtures of MgCl2 and Mg(NO3)2 by the Potentiometric Method at T = 298.15
Fluid Phase Equilibria, 2011Co-Authors: Mohammad Pournaghdy, Masoud Giahi, Mohammad A. Bagherinia, M. Monajjemi, Hossein Aghaie, Mehran AghaieAbstract:Abstract In this research, thermodynamic properties of the ternary electrolyte system (MgCl2 + Mg(NO3)2 + H2O) were investigated using a Potentiometric Method. The galvanic cell used had no liquid junction of type: Mg-ISE|MgCl2 (mA), Mg(NO3)2 (mB), H2O|Ag/AgCl. The measurements were performed at T = 298.15 K and at total ionic strengths from 0.001 to 8.000 mol/kg for different series of salt ratios r = m MgCl 2 / m Mg ( N O 3 ) 2 =1.00, 2.50, 5.00, 7.50, 10.00 and 15.00. The PVC based magnesium ion-selective electrode (Mg-ISE) and the Ag/AgCl electrode used in this work were prepared in our laboratory and showed a reasonably good Nernst response. The Pitzer ion interaction model and Harned rule were used to illustrate the ternary electrolyte system investigated. The experimental results showed that both Pitzer model and Harned rule were suitable to be used satisfactorily to describe this ternary system.