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Determination of berberine, an isoquinoline plant alkaloid, with antibacterial, antiparasitic, antifungal, hypotensive and antitumoral effects, was proposed by introducing square wave voltammetry on boron-doped diamond electrode. At optimized experimental parameters, in Britton-Robinson buffer solution pH 5 berberine provides 3 oxidation peaks (+0.63; +1.14 and +1.34 V) and one reduction (+0.15 V) ( vs. Ag/AgCl electrode), with good repeatability (relative standard deviation of 2.6% and 1.9% for 8 measurements at 0.5 and 10 mu M concentration level, respectively). Calibration curve was linear in wade linear range from 0.1 to 50 mu M with limit of detection of 0.04 mu M. The proposed procedure was successfully applied for the determination of berberine in seed extract from Argemone mexicana with satisfactory recovery ( 102-102.6%). The developed method may represent a sensitive alternative to highly toxic mercury electrodes, modified electrodes and chromatographic methods.

This paper presents for the first time the study of electrochemical behavior of well known immunosuppressant drug – rapamycin (sirolimus) using boron-doped diamond electrode. Rapamycin provided single and oval-shaped oxidation peak at +1.1 V vs. Ag/AgCl electrode in Britton–Robinson buffer solution at pH 3 confirming highly irreversible behavior of analyte at boron-doped diamond electrode. A differential pulse voltammetry was used for quantification of tested drug under the optimum experimental conditions. The calibration curve was linear over the range from 0.5 to 19.5 μM (R 2 = 0.9976) with detection limit of 0.22 μM. Repeatability of ten successfully measurements of three different concentrations (5, 10 and 15 μM) was 2.5, 1.9 and 1,7 %, respectively. Influence of most common biomolecules presented in urine samples was evaluated. The suggested analytical methodology was successfully applied for determination of rapamycin in four urine samples with excellent recoveries. The developed approach could be beneficial in analysis of rapamycin in biological samples using boron-doped diamond electrode as up-to-date electrochemical sensor and could represent inexpensive analytical alternative to separation methods.

A novel analytical approach for the sensitive determination of a β -carboline alkaloid, harmaline, was developed using pulse voltammetric techniques with a boron-doped diamond electrode. Cyclic voltammetry showed two irreversible oxidation peaks at about +0.90 and +1.20 V (vs. Ag/AgCl) in Britton–Robinson buffer solution at pH 5. Under optimized experimental conditions, differential pulse and square-wave voltammetry were elaborated for the determination of harmaline in a linear concentration range from 0.2 to 100.7 and from 0.4 to 104.5 μmol L −1 , respectively, with detection limits of 0.08 and 0.2 μmol L −1 , respectively. The practical feasibility of the developed method was demonstrated by quantification of harmaline in the extracts of natural food products such as Syrian rue ( Peganum harmala , also known as esphant , harmal , yuzerlik ) seeds, locally used as condiment and medicine in Turkey and the Near and Middle East, and the South American shamanic drink component Ayahuasca liane ( Banisteriopsis caapi ) with results in good agreement with those obtained by high-performance liquid chromatography as a reference method. The proposed sensor represents an effective electrochemical tool and inexpensive alternative for quality control analysis of food products containing harmaline.

The aim of this paper was the development and optimization of an electrochemical method for the degradation of two triketone herbicides, mesotrione, and sulcotrione, in a two-electrode undivided electrochemical cell equipped with commercially available, non-modified, electrode materials. The electrochemical parameters studied included five different electrode systems (Zr/Pt, Pd/Pt, C/Pt, Nb/Pt, and Ti/Pt), current densities (27.66, 55.33, …, 110.66 mA · cm−2) and pH values (3, 7, and 9) in 0.05 M sodium sulfate as supporting electrolyte. The electrical energy consumption and chemical oxygen demand were calculated for optimal conditions. The degradation efficiency was determined by high performance liquid chromatography (HPLC) equipped with a diode array detector, while the degradation products for both pesticides were identified and compared by ultra-high performance liquid chromatography (UHPLC)-mass spectrometry. The results could lead to an accurate estimate of their effect on the environment. A real water sample was used to study the influence of organic matter on pesticide degradation. Based on the results obtained the electrochemical treatment could be used for the successful removal of triketone herbicides from contaminated water.

Pharmaceutical compounds have been detected frequently in surface and ground water. Advanced Oxidation Processes (AOPs) were reported as very efficient for removal of various organic compounds. Nevertheless, due to incomplete degradation, toxic intermediates can induce more severe effects than the parent compound. Therefore, toxicity studies are necessary for the evaluation of possible uses of AOPs. In this study the effectiveness and capacity for environmental application of three different AOPs were estimated. They were applied and evaluated for removal of ibuprofen from water solutions. Therefore, two treatments were performed in a non-thermal plasma reactor with dielectric barrier discharge with and without a homogenous catalyst (Fe2+). The third treatment was the Fenton reaction. The degradation rate of ibuprofen was measured by HPLC-DAD and the main degradation products were identified using LC-MS TOF. Twelve degradation products were identified, and there were differences according to the various treatments applied. Toxicity effects were determined with two bioassays: Vibrio fischeri and Artemia salina. The efficiency of AOPs was demonstrated for all treatments, where after 15 min degradation percentage was over 80% accompanied by opening of the aromatic ring. In the treatment with homogenous catalyst degradation reached 99%. V. fischeri toxicity test has shown greater sensitivity to ibuprofen solution after the Fenton treatment in comparison to A. salina. (C) 2014 Elsevier B.V. All rights reserved.

A novel efficient differential pulse voltammetric (DPV) method for determination gallic acid (GA) was developed by using an electrochemical sensor based on [Cu(2)tpmc](ClO4)(4) immobilized in PVC matrix and coated on graphite (CGE) or classy carbon rod (CGCE). The proposed method is based on the gallic acid oxidation process at formed [Cu(2)tpmcGA](3+) complex at the electrode surface. The complexation was explored by molecular modeling and DFT calculations. Voltammograms for both sensors, recorded in a HNO3 as a supporting electrolyte at pH 2 and measured in 2.5 x 10(-7) to 1.0 x 10(-4) M of GA, resulted with two linear calibration curves (for higher and lower GA concentration range). The detection limit at CGE was 1.48 x 10(-7) M, while at CGCE was 4.6 x 10(-6) M. CGE was successfully applied for the determination of the antioxidant capacity based on GA equivalents for white, rose and red wine samples. This is the peer-reviewed version of the following article: Petković, B. B.; Stanković, D.; Milčić, M.; Sovilj, S. P.; Manojlović, D. Dinuclear Copper(II) Octaazamacrocyclic Complex in a PVC Coated GCE and Graphite as a Voltammetric Sensor for Determination of Gallic Acid and Antioxidant Capacity of Wine Samples. Talanta 2015, 132, 513–519. [https://doi.org/10.1016/j.talanta.2014.09.025] Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3364]

A simple and efficient procedure is described for electrochemical determination of trifluoperazine (TFP), a prominent compound in a large group of phenothiazine derivatives with potent physiological activity. This method is based on the electrochemical oxidation of TFP in Britton-Robinson buffer solution in pH 6 at a boron-doped diamond electrode. Cyclic voltammetry provided a four well defined oxidation peaks at + 0.65, + 0.83, + 1.06 and + 1.35 V (vs. Ag/AgCl/3 M KCl electrode). Differential pulse voltammetry was applied as a very sensitive analytical technique for the determination of micromolar amounts of TFP. Two oxidation peaks on higher potentials were chosen for quantification of TFP. Under optimized conditions, the analytical curves obtained were linear in the TFP concentration range of 1.0 to 37.0 mmol L-1, with a detection limit of 0.7 and 0.6 mmol L-1, respectively. The effect of interfering agents (common urinary compounds) appeared to be negligible confirming the favourable selectivity of the method. The proposed method was analytically applied by determination of trifluoperazine content in model human urine samples with good accuracy (recoveries varied from 97% to 104%). The developed approach could be beneficial in analysis of TFP in biological samples using a boron-doped diamond electrode as an up-to-date electrochemical sensor and could represent an inexpensive analytical alternative to separation methods.

We synthesized three dumbbell-like compounds 2a-c, each containing two C-60 groups at the periphery and pyromellitic diimide (PMDI) in the middle, and examined their electronic as well as assembly characteristics with both experimental and computational methods. Cyclic voltammetry (CV) measurements revealed that each of three electron-accepting (AAA) triads could accommodate up to eight electrons. Computational studies (density functional theory, DFT) of 2a-c at PBEPBE/6-311G(d, p) level of theory, with B3LYP/6-31G(d) optimized geometries, revealed that HOMO-LUMO energy gaps are similar to those of the model compound [6,6]-phenyl-C-61-butyric acid methyl ester (PCBM). Compounds 2a-c were also found to assemble into vesicles and nanoparticles on the copper grid (100-300 nm, TEM), while giving more sizeable aggregates after a deposition on the glass (SEM, gt 5 mm). Understanding the packing of 2a-c on various solid substrates, as well as the assembly characteristics in general, is important for tuning the properties and fabrication of electronic/optical devices. On the basis of the results of conformational analysis (MM and DFT calculations), we deduced that different alkyl spacers in 2a-c ought to play a role in pi-pi interactions between the aromatic components of the triad to guide the packing and therefore morphology of the material. Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3369]

Complexes 1-4, [Ru(L)(bpy)(2)]PF6, where bpy=2,2-bipyridine; HL=3-methylpyridine-2-carboxylic acid (HL1), 6-methylpyridine-2-carboxylic acid (HL2), 5-bromopyridine-2-carboxylic acid (HL3) and 6-bromopyridine-2-carboxylic acid (HL4), were synthesized and characterized. The electrochemical character of the complexes was investigated by cyclic voltammetry revealing two reversible reduction waves in the negative range of potentials, most likely due to a reduction of the bipyridine moiety. Cytotoxicity studies by MTT assay for 72h of drug action revealed that 2-4 exhibited moderate activity in cervical human tumor cells (HeLa). Complex 2 exhibited low activity in colon cancer LS-174 cells (180 +/- 10), while all complexes were devoid of activity in lung cancer A549 and non-tumor MRC-5 cells, up to 200M. Combinational studies of the most active complex 2, with pharmacological modulators of cell redox status, L-buthionine-sulfoximine (L-BSO) or N-acetyl-L-cysteine (NAC), showed that when L-BSO potentiated, 2 induced a sub-G1 peak of the cell cycle in the HeLa cell line. UV-vis and cyclic voltammetry were performed in order to investigate the binding mode of 2 to DNA and suggested intercalation for the complex-DNA interaction. [GRAPHICS] This is the peer-reviewed version of the following article: Baroud, A. A.; Mihajlović-Lalić, L. E.; Gligorijević, N.; Aranđelović, S.; Stanković, D.; Radulović, S.; Van Hecke, K.; Savić, A.; Grgurić-Šipka, S. Ruthenium(II) Bipyridine Complexes: From Synthesis and Crystal Structures to Electrochemical and Cytotoxicity Investigation. Journal of Coordination Chemistry 2017, 70 (5), 831–847. [https://doi.org/10.1080/00958972.2017.1282611] Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3138]

The overall aim of this paper was to compare the multielement composition and antioxidant capacity of two Montenegrin Merlot wines obtained from specific vine clones (VCR1 and VCR 101) along with commercial Merlot wine throughout the consecutive vintages in 2010 and 2011. Elemental composition was analysed using inductively coupled plasma optical emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS). Additionally, antioxidant capacity was assessed by cyclic voltammetry. VCR 1 wine from 2011 stood out for its elemental composition. On the other hand, antioxidant capacity of VCR 101 wines was the highest one for the both vintages. According to the experimental data obtained, all three wines are good source of essential elements and products with a significant antioxidant activity and specific geographical origin. Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3016]

In the present paper, the electrochemical behavior and the properties of two modified glassy carbon (GC) electrodes used for quantification of gallic acid in sweet wines were compared. A comparative study was conducted between titanium nitride- or wolfram carbide-doped reduced graphene oxide, labeled as TNrGO and WCrGO, respectively, modified GC electrodes, which are promising composite nanomaterials for electroanalytical applications. For the first time, WCrGO was synthesized and its electroanalytical properties compared with those of TNrGO. Results showed that the proposed materials exhibited enhanced characteristics, e.g., low limits of detection (1.1 mu M and 3.1 mu M for TNrGO and WCrGO, respectively), wide linear ranges (for TNrGO 4.5-76 mu M and for WCrGO 10-100 mu M), low adsorption, and low background current, which make them promising candidates for electrochemical sensing applications. Magbiovin project (FP7-ERAChairs-Pilot Call) [621375] Ministry of Education, Science and Technology, the Republic of Serbia [OI 172030] Grant Agency of the Slovak Republic [1/0489/16] Grant Agency of the Slovak Republic VEGA [2/0128/16] info:eu-repo/semantics/publishedVersion

For the first time, in this study electrochemical oxidation behavior of pesticide maneb is evaluated. Due to the structure electroanalytical quantification of maneb has not been exploited enough. Maneb electrochemical behavior was investigated using glassy carbon (GC), graphene modified glassy carbon (GR/GC) and boron doped diamond (BDD) electrodes. It is shown that only BDD shows satisfactory results toward maneb detection. Based on this, a simple, sensitive and selective electroanalytical method for determination of pesticide maneb using differential pulse voltammetry (DPV) is proposed, with a working linear range of 80-3000nM and the limit of detection of 24nM. The developed methodology has been applied for the determination of maneb in river water samples with satisfactory recovery. Additionally, this green method, being simple, fast, and free of chemical-reduction reagents, offers several advantages over modified electrodes and expands the scope of BDD based electrochemical sensing devices, with promise for wider applications in environmental analysis. Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3213]

Propolis, as a beneficial natural product, has found application in the food and pharmaceutical industries as a food preservative, active packaging material as well as a main component of propolis containing products. Quality control of propolis has thus gained in importance. We used simple, fast, and low-cost techniques such as UV/Vis spectrophotometry and cyclic voltammetry applied in combination with principal component analysis to confirm the presence of two botanical sub-types of propolis. Cyclic voltammetry, as a green, sensitive, and convenient technique suitable for investigation of chemical profile, together with multivariate chemometrics technique, was used for the first time for characterization and classification of propolis. UV/Vis spectroscopy was applied in two aspects, absorption at certain wavelength for the quantitative determination of analytes, i.e. determination of quality control parameters, and spectral profiles, for the confirmation of the existence of two botanically different poplar types. All investigated Serbian propolis samples were characterized with specific chemical patterns and were classified in two main botanical varieties, so-called orange and blue. The results confirmed that the applied methods have a potential to be used for the discrimination of complex natural products such as propolis. Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3032]

Colchicine (COLC) is a natural toxic product and secondary metabolite most commonly used to treat gout. In this study, its electrochemical behavior and determination was investigated by employing modification-free boron-doped diamond electrode (BDDE). Besides, its interaction with DNA was monitored using electrochemical methods. It was found that oxidation of this compound proceeds in two steps, where first sharp and well defined oxidation peak occurs at potential of around 1.19V, and second one at around 1.37V, in Britton-Robinson buffer solution at pH7.5. Wide dynamic range from 1 to 100 mu M was obtained with a detection limit (3 sigma(intercept)/slope) of a 0.26 mu M, based on the evaluation of first oxidation peak using differential pulse voltammetry. The proposed method was also found to be suitable for monitoring interaction of this drug with DNA as important segment for medical use. Concerning the validation, the analytical procedure shows excellent selectivity and sensitivity toward COLC detection and after method development it was successfully used for its quantification in pharmaceutical preparation and human serum sample, with satisfactory recovery. Obviously, this approach can be promising replacement for time-consuming and expensive separation methods. Magbiovin project [621375] Ministry of Education, Science and Technology, the Republic of Serbia [OI 172030] Grant Agency of the Slovak Republic [1/0489/16] info:eu-repo/semantics/publishedVersion

Redox properties of a set of aryldiketo acids (ADKs), small organic molecules that comprise 2,4-dioxobutanoic acid moiety, were studied. Along with well-known HIV-1 integrase (IN) inhibition, ADKs exert widespread biological activities. The aim of this work was to evaluate the effects of aryl substitutions on the properties of the dioxobutanoic moiety that is involved in key interactions with metal ions within the active sites of target enzymes. The effect of pH on the electronic properties of nine congeners was examined using cyclic voltammetry and differential pulse polarography. The compounds were chosen as a simple set of congeners bearing Me-groups on the phenyl ring, which should not be involved in electrochemical reactions, leaving the diketo moiety as the sole electrophore. The substitution pattern was systematically varied, yielding a set having different torsion between the phenyl ring and the aryl keto group (Ar–C(O)). The protonation state of the ADKs at different pH values was determined from the experimentally obtained pKa values. The results showed that an equal number of protons and electrons were involved in the oxidation and reduction reactions at the surface of the electrode. Quantitative linear correlations were found between the reduction potentials and the energies of the frontier orbitals, calculated for neutral, mono-anionic and the corresponding radical anionic species, and the steric parameter as two independent variables. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 172035]

A simple and fast method for determination of two phenothiazine drugs, chlorpromazine (CPZ) and thioridazine (TDZ), at the boron-doped diamond electrode (BDDE) was proposed. Oxidation peaks on potentials higher than 1 V were used for quantitation of investigated phenothiazines due to better selectivity over common interfering compounds in urine. Differential pulse voltammetry was applied for trace determination of CPZ and TDZ, in Britton-Robinson buffer solution at optimal pH. Under optimized DPV conditions a linear analytical curve was obtained from 1.0x10(-7) to 4.0x10(-5) M with a detection limit of 0.3x10(-7) M (for CPZ) and in the concentration range of 2x10(-7) M to 4.0x10(-5) M, with a detection limit of 1.2x10(-7)M (for TDZ). The applicability of the method was proved by determination of CPZ and TDZ by proposed procedures in spiked urine samples. The electrochemical behavior of those two important tranquilizers in different solvents was described, exploring the possibility of simultaneous determination.

Toxic effects of unconjugated bilirubin (BR) in neonatal hyperbilirubinemia have been related to redox and/or coordinate interactions with Cu2+. However, the development and mechanisms of such interactions at physiological pH have not been resolved. This study shows that BR reduces Cu2+ to Cu1+ in 1:1 stoichiometry. Apparently, BR undergoes degradation, i.e. BR and Cu2+ do not form stable complexes. The binding of Cu2+ to inorganic phosphates, liposomal phosphate groups, or to chelating drug penicillamine, impedes redox interactions with BR. Cu1+ undergoes spontaneous oxidation by O-2 resulting in hydrogen peroxide accumulation and hydroxyl radical production. In relation to this, copper and BR induced synergistic oxidative/damaging effects on erythrocytes membrane, which were alleviated by penicillamine. The production of reactive oxygen species by BR and copper represents a plausible cause of BR toxic effects and cell damage in hyperbilirubinemia. Further examination of therapeutic potentials of copper chelators in the treatment of severe neonatal hyperbilirubinemia is needed. This is the peer-reviewed version of the following article: Božić, B.; Korać, J.; Stanković, D. M.; Stanić, M.; Popović-Bijelić, A.; Bogdanović Pristov, J.; Spasojević, I.; Bajčetić, M. Mechanisms of Redox Interactions of Bilirubin with Copper and the Effects of Penicillamine. Chemico-Biological Interactions 2017, 278, 129–134. [https://doi.org/10.1016/j.cbi.2017.10.022] Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3106]

A boron-doped diamond electrode was used as an electrochemical sensor for the determination of phlorizin (aka phloridzin, phlorrhizin) using square wave voltammetry (SWV). Phlorizin (Phl) exhibited a well-defined oxidation peak at +0.9 V (versus Ag/AgCl electrode 3 M KCl) in solutions with a pH value of 6.0. Parameters such as pH value and scan rate were optimized for cyclic voltammetry as well as amplitude and frequency for SWV. The sensor gave excellent response with a wide linear dynamic range for concentrations of phlorizin from 3 to 100 mu M with a detection limit of 0.23 mu M and a good repeatability (+/- 0.9%, n = 7 measurements, c = 10 mu M). The effect of interferences by most common compounds was tested, and the method was successfully applied to the determination of the title compound in apple root extracts and urine samples with satisfactory recovery. Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3036]

Using microwave-hydrothermal method for synthesis of composite, high surface density of hydroxyl groups, as an active adsorption sites for arsenic, was obtained. Adsorption mechanisms of As(III) and As(V) onto zirconium doped titanium-dioxide (Zr-TiO2) was investigated and proposed using macroscopic and microscopic methods. Obtained results are suggesting innersphere and outer-sphere adsorption mechanisms for As(III) and As(V), respectively. This allowed us identification of parameters that are critical for the successful removal of arsenic from water, essential information for further optimization of the removal process. Composite was further applied for the removal of As(III) and As(V) from water in a dynamic flow through reactor. Column study proved that removal of both arsenic species below value recommended by WHO can be achieved. Elution of As(III) and As(V) from the composite can be done by using small amount of 0.01 M NaOH solution resulting in preconcentration of arsenic species and possible multiple usage of composite. This is the peer-reviewed version of the article: [https://doi.org/10.1080/09593330.2016.1255664] [http://cer.ihtm.bg.ac.rs/handle/123456789/2151]

The boron-doped diamond electrodes (BDDEs) with different dopant levels were applied as advanced, mercury-free and modification-free electroanalytical platforms for simple and reliable quantification of benzodiazepines, bromazepam (BZ) and alprazolam (ALZ). Cyclic voltammetric measurements revealed that the electrode reactions of both analytes were manifested by one irreversible and diffusion-controlled reduction peak at -1.10V in Britton-Robinson buffer of pH 11 for BZ using lab-made BDDE with 1000 ppm B/C ratio and -0.84V in BR buffer of pH 5 for ALZ using commercial BDDE with 1000 ppm B/C ratio. Differential pulse voltammetry was used for construction of calibration curves for BZ and ALZ, respectively, with the analytical parameters as follows: the linear dynamic ranges of 1 x 10(-6)-1 x 10(-4) and 8 x 10(-7)-1 x 10(-4) mol/L, the detection limit of 3.1 x 10(-7) and 6.4 x 10(-7) mol/L and the excellent repeatability with the relative standard deviation below 3% for both drugs. The developed methods were applied to analysis of the pharmaceutical tablets with the recoveries from 97.33 to 100.85% for BZ and from 94.14 to 101.32% for ALZ. The usage of BDDEs as advanced electrochemical sensors in drug analysis represents a facile and effective analytical approach which may replace mercury-based sensors and chemically modified electrodes in previous benzodiazepines sensing. This is the peer-reviewed version of the following article: Samiec, P.; Švorc, Ľ.; Stanković, D. M.; Vojs, M.; Marton, M.; Navrátilová, Z. Mercury-Free and Modification-Free Electroanalytical Approach towards Bromazepam and Alprazolam Sensing: A Facile and Efficient Assay for Their Quantification in Pharmaceuticals Using Boron-Doped Diamond Electrodes. Sensors and Actuators, B: Chemical 2017, 245, 963–971. [https://doi.org/10.1016/j.snb.2017.02.023] Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3081]

Herein we report effects of partial substitution of Fe3+ by Y3+ in magnetite (Fe3O4) on morphology and inorganic arsenic species adsorption efficiency of the Fe3−x Y x O4 nanoparticles formed. The series of Fe3−x Y x O4 (x = 0.00, 0.042 and 0.084, labeled as Y00, Y05 and Y10, respectively) was synthesized using co-precipitation followed by microwave-hydrothermal treatment (MW) at 200 °C. With increase of yttrium content (x value), both the morphological inhomogeneity of the samples and the fraction of spinel nanorods as compared to spinel pseudospherical particles increased. By both transmission electron microscopy and x-ray powder diffraction analyses, it was determined that the direction of growth of the spinel nanorods is along the [110] crystallographic direction. The Fe3−x Y x O4 affinities of adsorption toward the inorganic arsenic species, As(III) (arsenite, AsO3 3−) and As(V) (arsenate, AsO4 3−), were investigated. Increased Y3+ content related to changes in sample morphology was followed by a decrease of As(III) removal efficiency and vice versa for As(V). The increase in Y3+ content, in addition to increasing the adsorption capacity for As(V), significantly expanded the optimum pH range for the maximum removal and decreased the contact time for necessary 50% removal (t 1/2) of As(V) (Y00: pH 2–3, t 1/2 = 3.12 min; Y05: pH 2–6, t 1/2 = 2.12 min and Y10: pH 2–10, t 1/2 = 1.12 min). The results point to incorporation of Y3+ in the crystal lattice of magnetite, inducing nanorod spinel structure formation with significant changes in sorption properties important for the removal of inorganic arsenic from waters. This is the peer-reviewed version of the article: Nanotechnology, 2019, 30, 47, 475702, [https://dx.doi.org/10.1088/1361-6528/ab3ca2] Published version: [http://cer.ihtm.bg.ac.rs/handle/123456789/3243]

Six novel gold(III) complexes containing O,O'-dialkyl-(S,S)-ethylenediamine-N,N'-di-2-(3-cyclohexyl)propanoate ([AuCl2{(S,S)-R(2)eddch}]PF6, R = Me, Et, n-Pr, n-Bu, i-Bu, i-Am; 1-6, respectively) were synthesized and characterized by elemental analysis, UV/Visible, IR and NMR spectroscopy, mass spectrometry and differential pulse voltammetry. Density functional theory (DFT) calculations confirmed that diastereoisomer with the N,N' atoms configured (S,S) was the most stable. In vitro antiproliferative activity was determined against human cervix adenocarcinoma HeLa and human myelogenous leukemia K562 tumor cell lines, as well as against rested and stimulated normal immunocompetent human peripheral blood mononuclear cells (PBMC) using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Complex 6 expressed the highest activity against K562 cells (IC50 = 3.8 +/- 0.5 mu M). Apoptosis, seen as condensation of HeLa cell nuclei was the mode of cell death induced by complexes 2-6. Complexes 3-6 induced death of K562 cells inhibiting cell entry in mitosis. Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3497]

Electrochemical treatment is a new trend for the purification of textile industry wastewater which containing azo dyes. In this paper the electrochemical treatment was used for decolorization of azo dye Reactive Blue 52. The efficiency of decolorization was compared for different electrochemical systems which were all equipped with Fisher platinum electrode as anode and a different cathode (Zr, Pd, C) in sodium sulfate as supporting electrolyte. In order to find optimal conditions the influence of various voltage and pH values of initial dye solution was studied. Decolorization rate was monitored by spectrophotometer while degradation products were identified by high performance liquid chromatography-diode array detector (HPLC-DAD). Results of HPLC analysis confirmed presence of various degradation products in electrochemical systems, which indicated different mechanism of degradation. This was also confirmed by Ek–t curve. In terms of power consumption the most cost effective system was with the graphite cathode (C/Pt).

A series of novel fulleropyrrolidine–phthalimide dyads was synthesized and their electrochemical and self-assembly properties were investigated. Efficient synthesis of acceptor– acceptor dyads was performed under microwave irradiation. Fine-tuning of the second redox potentials in the dyads was

The complexation reactions between octaazamacrocyclic ligand N,N',N '',N'"-tetrakis(2-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane (tpmc) and Co2+, Ni2+, Zn2+ and Cu2+ metal cations have been studied conductometrically in acetonitrile and aqueous solutions. The conductance data exhibit different stoichiometry of the complexes in two studied solutions. In most cases 1:1 (ML) complexes were formed while in some cases 2:1 (M2L) complexes are evident. The stability constants of the resulting 1:1 complexes were determined by computer fitting of the conductance/mole ratio data. Theoretical DFT calculations were used to explain metal binding capability of tpmc ligand and the binding sequences were found to follow the order: Cu2+ gt gt Ni2+ gt Co2+ gt Zn2+. The combination of results obtained by this theoretical approach and conductometric study successfully explains sensitivity and selectivity of recently developed tpmc based ISE and could play a guiding role in planning experiments with large macrocyclic ligands. Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3473]

Tembotrione is herbicide which belongs to the triketone group of herbicides. It’s registered as a selective, post-emergence herbicide developed for the control of a broad spectrum broadleaf and grassy weeds in corn. There is little information about tembotrione because of his short presence in the market. Due to its ever wider application, it is important to know the details of its chemical characteristics and redox processes, including biogeochemical transformation and migration after application to agricultural land, which could contribute to its efficient and safer application. In this paper we examined voltammetric behavior of tembotrione using Silver/Amalgam (Ag/Hg) electrode. For the investigation of electrochemical behavior we used the cyclic voltammetry technique, with conventional three-electrode cell and electrochemical workstation. During the experiment pH values of solution varieties while constant concentration of tembotrione was maintained. Cyclic voltammograms were recorded at pH values 6, 8, 10 and 12, at which tembotrione was electrochemically active. At this pH values two signals were observed. Optimum pH value, at which the current intensity was greatest, was 12. Obtained results provide relevant information on the electrochemical behavior of tembotrione, which can serve as a basis for the development of electrochemical techniques for the removal and degradation of this pesticide in the environment.

This paper presents a method for the determination of trace contents of silver, copper, iron, palladium, zinc and platinum in refined gold samples. A simultaneous inductively coupled plasma atomic emission spectrometer in the radial torch position and with a cross flow nebulizer was used for the determinations. In order to compare the different calibration strategies, two sets of calibration standards were prepared. The first set was based on matrix matched calibration standards and the second was prepared without the addition of matrix material. The detection limits for the matrix-matched calibrations were higher for some elements than those without matrix matching. In addition, the internal standardization method was applied and experiments indicated that indium was the best option as the internal standard. The obtained results for gold samples with matrix matched and matrix free calibrations were compared with the results obtained by the standard addition method. The accuracy of the methods was tested by performing a recovery test. The recoveries for the spiked sample were in the range of 90-115 %. The accuracy of the methods was also tested by analysis of a certified reference material of high purity gold AuGHP1. The best results were achieved by matrix free calibration and standard addition method using indium as the internal standard at a wavelength of 230 nm. Ovaj rad prikazuje metodu za određivanje niskih sadržaja srebra, bakra, gvožđa, paladijuma, cinka i platine u uzorcima rafnisanog zlata. Za ispitivanja je korišćen atomski emisioni spektrometar sa induktivno kuplovanom plazmom, radijalno postavljenim plamenikom sa unakrsnim raspršivačem. Da bi se uporedile različite strategije kalibracije pripremljena su dva seta kalibracionih standarda. Prvi set kalibracionih standarda sa i drugi set standarda bez dodatka matriksa. Granice detekcije dobijene pri korišćenju standarda sa dodatkom matriksa su više za neke elemente od kalibracija bez dodatka matriksa. Takođe, primenjena je i metoda unutrašnje standardizacije, eksperimenti su pokazali da je indijum najbolji izbor za unutrašnji standard. Rezultati analiza uzorka zlata dobijenih korišćenjem standarda sa i bez dodatka matriksa upoređeni su sa metodom standardnog dodatka. Tačnost metoda ispitana je prinosom standardnog dodatka i dobijene su vrednosti u opsegu od 90 do 115 %. Tačnost metode, takođe, je proverena korišćenjem sertifikovanog referentnog materijala visokočistog zlata AuGHP1. Najbolji rezultati postignuti su upotrebom kalibracionih standarda bez dodatka matriksa i metodom standardnog dodatka upotrebom indijuma kao unutrašnjeg standarda na talasnoj dužini od 230 nm.

This work presents the electrochemical behavior of levodopa (L-DOPA), at boron-doped diamond (BDD) electrodes, using cycling voltammetry (CV), in Britton-Robinson (BR) buffer solution, and application of the proposed electrode for the determination of L-DOPA in extracts from the seeds of velvet bean (Mucuna prurita Hook or Mucuna pruriens (L.) DC.). L-DOPA provides a well-defined and single oval-shape oxidation peak at +0.8 V vs. Ag/AgCl (3 M KCl) reference electrode in BR buffer solution at pH 3.0. Experimental parameters, such as pH of supporting electrolyte and square wave voltammetry (SWV) operating parameters (frequency and modulation amplitude) were optimized. The effect of possible interferences was evaluated. Under optimal conditions the detection limit of the developed method was 0.8 mu M and the calibration curve for L-DOPA was linear in the range from 2 to 100 mu M. The proposed method was successfully applied to the determination of L-DOPA in an extract from the seeds of Mucuna prurita. The obtained result was in good agreement with obtained by photometry with 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS). The developed approach can be beneficial for the quantification of L-DOPA using a BDD electrode as up-to-date potential alternative sensor for electroanalytical applications.

8-Quinolinecarboxaldehyde selenosemicarbazone (H8qasesc) and its octahedral Co(III) complex were characterized by single crystal X-ray diffraction analysis, spectroscopy methods and cyclic voltammetry. The antineoplastic activity of the ligand and the complex has been assessed on an acute monocytic leukemia cell line (THP-1) and AsPC-1 cancer stem cell (CSC) line derived from a patient suffering from pancreatic adenocarcinoma, with cisplatin (CDDP) as a reference compound. Evaluation involved determination of pro-apoptotic activity, changes in cell cycle distribution, the role of caspase activation in the process of cell death, and the ability of the investigated compounds to challenge reprogramming of the CSC phenotype. Compared to CDDP, treatment with H8qasesc induced a higher apoptotic response in both investigated cell lines. Apoptosis triggered by H8qasesc was highly caspase-dependent but did not include activation of either caspase-8 or -9. According to cell cycle changes H8qasesc delayed the transition of cells during DNA replication but in a manner different from that of CDDP. The ligand did not show nuclease activity on pUC19 plasmid, while docking studies disclosed that it does not have intercalating properties. Treatment of THP-1 cells with the Co(III) complex resulted in a strong toxic response, whereas cell death in the treated AsPC-1 line was not achieved for 24 h. Additionally, the complex concentration-dependently digested plasmid DNA which might be the cause of its cytotoxic activity. Finally, H8qasesc successfully initiated reprogramming of the CSC phenotype in the AsPC-1 cell line. This is peer-reviewed version of the following article: Filipović, N. R.; Bjelogrlić, S.; Portalone, G.; Pelliccia, S.; Silvestri, R.; Klisurić, O.; Senćanski, M.; Stanković, D.; Todorović, T. R.; Muller, C. D. Pro-Apoptotic and pro-Differentiation Induction by 8-Quinolinecarboxaldehyde Selenosemicarbazone and Its Co(III) Complex in Human Cancer Cell Lines. MedChemComm 2016, 7 (8), 1604–1616. [https://doi.org/10.1039/c6md00199h] Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3599]

In this work new designed, highly sensitive electrochemical method is developed for the determination of nitrites in tap water using glassy carbon electrode modified with graphene nanoribbons (GNs/GCE). Graphene nanoribbons (GNs) have been newly synthetized and aligned to the surface of glassy carbon electrode (GCE) and exhibited excellent electrocatalytic activity for nitrite oxidation with a very high peak currents. Studies about electrochemical behavior and optimization of the most important experimental conditions were done using cyclic voltammetry (CV), while quantitative studies were done with amperometric detection. Nitrite provides a well-defined, oxidation peak at +0.9 V (vs. Ag/AgCI, 3.0 M KCI) in Britton-Robinson buffer solution (BRBS) at pH 3. The influence of most possible interferent ions has been examined and was found to be negligible. Under optimized experimental conditions in BRBS at pH 3 linear calibration curves were obtained in the range from 0.5 to 105 mu M with the detection limit of 0.22 mu M. Reproducibility of ten replicate measurements of 1 M of nitrite was estimated to be 1.9%. Proposed method and constructed sensor is successfully applied for the determination of nitrite present in tap water samples without any pretreatment. This developed method represents inexpensive analytical alternative approach compared to other analytical methods. (C) 2016 Elsevier B.V. All rights reserved. This is peer-reviewed version of the following article: Mehmeti, E.; Stanković, D. M.; Hajrizi, A.; Kalcher, K. The Use of Graphene Nanoribbons as Efficient Electrochemical Sensing Material for Nitrite Determination. Talanta 2016, 159, 34–39. [https://doi.org/10.1016/j.talanta.2016.05.079]

In this work, a simple and rapid electrochemical method is presented for the voltammetric determination of histamine based on carbon paste electrodes bulk-modified with single-walled carbon nanotubes. As monitored in cyclic voltammetry histamine undergoes an irreversible electrochemical oxidation with a peak potential of ca. +1.25 V (vs. Ag/AgCl, 3 mol L-1 KCl) in phosphate buffer solution (PBS, 0.1 mol L-1, pH 6.0). At optimized differential pulse voltammetric parameters, the current response of histamine was linearly proportional to its concentration in the range from 4.5 to 720 mu mol L-1. A low limit of detection of 1.26 mu mol L-1 and a limit of quantification of 3.78 mu mol L-1 of histamine, as well as good reproducibility (RSD = 0.48-3.40 %) were obtained using the carbon paste electrode modified with single-walled carbon nanotubes. The proposed sensor was successfully applied to the determination of histamine in commercial beer and wine samples.

In this study, a novel electrochemical sensor for quantification of ascorbic acid with amperometric detection in physiological conditions was constructed. For this purpose, cobalt and nickel ferrites were synthesized using microwave and ultrasound assistance, characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and X-ray powder diffraction (XRPD), and used for modification of glassy carbon paste electrode (GCPE). It was shown that introducing these nanoparticles to the structure of GCPE led to increasing analytical performance. Co ferrite modified GCPE (CoFeGCPE) showed better characteristics toward ascorbic acid sensing. The limit of detection (LOD) obtained by sensor was calculated to be 0.0270 mg/L, with linear range from 0.1758 to 2.6010 mg/L. This sensor was successfully applied for practical analysis, and the obtained results demonstrated that the proposed procedure could be a promising replacement for the conventional electrode materials and time-consuming and expensive separation methods. (C) 2016 Elsevier Inc. All rights reserved. Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3336]

This work presents the simultaneous determination of catechol (CC) and hydroquinone (HQ), employing a modified carbon paste electrode (CPE) with ferrite nanomaterial. Ferrite nanomaterial was doped with different amount of cobalt and this was investigated toward simultaneous oxidation of CC and HQ. It was shown that this modification strongly increases electrochemical characteristics of the CPE. Also, electrocatalytic activity of such materials strongly depends on the level of substituted Co in the ferrite nanoparticles. The modified electrodes, labeled as CoFerrite/CPE, showed two pairs of well-defined redox peaks for the electrochemical processes of catechol and hydroquinone. Involving of ferrite material in the structure of CPE, cause increase in the potentials differences between redox couples of the investigated compounds, accompanied with increases in peaks currents. Several important parameters were optimized and calibration curves, with limits of detection (LOD) of 0.15 and 0.3 mu M for catechol and hydroquinone, respectively, were constructed by employing amperometric detection. Effect of possible interfering compounds was also studied, and proposed method was successfully applied for CC and HQ quantification in real samples. Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3507]

A simple, sensitive, and economically viable electrochemical method for the determination of ajmalicine was developed. The procedure involves a glassy carbon electrode modified with gold nanoparticles (GCE/AuNPs). In the work presented here gold nanoparticles were attached to the glassy carbon electrode by adsorption. Cyclic voltammetry was used for the first time for the electrochemical characterization of ajmalicine and differential pulse voltammetry for its quantitative determination. Britton-Robinson buffer solution in a range of pH values served as supporting electrolyte. The experimental conditions were optimized and it was found that ajmalicine provided a well-defined oxidation peak at a potential of +0.8 V vs. Ag/AgCl (3 M KCl). The method for the determination of ajmalicine showed a dynamic range for concentrations from 5 to 50 A mu M with a detection limit of 1.7 A mu M, good repeatability (RSD of 1.4 %) and reproducibility (RSD of 2.5 %). The effect of possible interferents (yohimbine, reserpine) appeared to be negligible. The proposed procedure was successfully applied for the first time to the determination of ajmalicine in commercially available oral solutions for medical applications with results in good agreement with the declared content of ajmalicine. [GRAPHICS]

In this paper electrochemical behavior and sensitive determination of vitamin B12 was studied by using boron doped diamond (BDD) electrode. Cyclic voltammetry and square wave voltammetry were used to investigate the performance of BDD electrode for this purpose. The calibration curve, constructed by plotting oxidation peak current against concentration, obtained in Britton-Robinson buffer solution at pH 2.0 was linear over the wide concentration range of 2-35 mu M with detection limit of 0.7 mu M. Influence of most common interferences compounds was investigated and proposed procedure was successfully applied for quantification of vitamin B12 in real samples, with satisfactory recovery (98-105%). (C) 2016 The Electrochemical Society. All rights reserved.

Two different approaches, spectroscopic and electrochemical, were applied for the rough determination of the antioxidative capacity of honey samples. Honey samples of diverse botanical origin were collected in different geographical regions of Serbia. The total phenolic content (TPC) was determined by the Folin-Ciocalteu method. Cyclic voltammograms on a glassy carbon electrode in KCl supporting electrolyte were used to check the electrode sensitivity to the presence of honey. In order to calculate the Trolox equivalent antioxidant capacity (TEAC) of the studied honey samples, cyclic voltammograms were recorded for the Trolox standard. The results were expressed as mu mol of Trolox equivalents per kg of sample (mu mol TE kg(-1)). Good correlations were observed between the cyclic voltammetry data and the TPC determined by the Folin-Ciocalteu method and the radical scavenging activity (RSA) determined using the DPPH center dot(1,1-diphenyl-2-picrylhydrazyl) radical test. Cyclic voltammetry appears to be a highly attractive alternative method for a rapid estimation of the antioxidative capacity of honeys. It was found that polyfloral honey samples had the highest, whereas acacia honey showed the lowest values of TPC. Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3343]

Essential oil of Carum copticum seeds, obtained from a local shop, was extracted and content of thymol was analyzed using square-wave voltammetry at boron-doped diamond electrode. The effect of various parameters, such as pH of supporting electrolyte and square-wave voltammetric parameters (modulation amplitude and frequency), was examined. In Britton-Robinson buffer solution (pH 4), thymol provided a single and oval-shaped irreversible oxidation peak at +1.13 V versus silver/silver chloride potassium electrode (3 M). Under optimal experimental conditions, a plot of peak height against concentration of thymol was found to be linear over the range of 4 to 100 mu M consisting of two linear ranges: from 4 to 20 mu M (R-2 = 0.9964) and from 20 to 100 mu M (R-2 = 0.9993). The effect of potential interferences such as p-cymene and gamma-terpinene (major components in essential oil of C copticum seeds) was evaluated. Thus, the proposed method displays a sufficient selectivity toward thymol with a detection limit of 3.9 mu M, and it was successfully applied for the determination of thymol in essential oil of C copticum seeds. The Prussian blue method was used for validation of the proposed electroanalytical method. This is the peer-reviewed version of the following article: Stanković, D. M. Sensitive Voltammetric Determination of Thymol in Essential Oil of Carum Copticum Seeds Using Boron-Doped Diamond Electrode. Analytical Biochemistry 2015, 486, 1–4. [https://doi.org/10.1016/j.ab.2015.06.026]

An ethanol biosensor based on alcohol dehydrogenase (ADH) attached to Au seeds decorated on magnetic nanoparticles (Fe3O4"Au NPs) is presented. ADH was immobilized on Fe3O4"Au NPs, which were subsequently fixed by a magnet on a carbon paste electrode modified with 5% (m:m) MnO2. Optimum conditions for the amperometric determination of ethanol with the biosensor were as follows: working potential +0.1 V (vs. Ag/AgCl); supporting electrolyte: 0.1 M phosphate buffer solution at pH 6.8 containing 0.25 mM of the coenzyme (NAD+); working electrode: carbon paste with magnetically attached Fe3O4"Au NPs (0.012 mg . cm(-2) electrode area) with immobilized alcohol dehydrogenase (120 units per cm(2) of electrode area). Linearity between signal and concentration was found for the range from 0.1 to 2.0 M ethanol (r(2) = 0.995) with a detection limit of 0.07 M, a sensitivity of 0.02 mu A . mM(-1) . cm(-2), a reproducibility of 4.0% RSD, and a repeatability of 2.7% RSD. The results for the determination of ethanol in alcoholic beverages showed good agreement with gas chromatography (GC) with recovery of 96.0-108.8%. Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3331]

In order to elucidate the role of B, N, and P dopants in carbon materials on the kinetics of oxygen reduction reaction (ORR) and to provide a fair comparison of the effects of each dopant, a series of ordered mesoporous carbons (OMCs) with low concentration of heteroatoms ( lt 1 at%) has been prepared. Doped OMCs were characterized using X-ray photoelectron spectroscopy (XPS), inductively coupled plasma optical emission spectroscopy (ICP-OES), Raman spectroscopy, X-ray powder diffraction (XRD), and N-2 physisorption measurements. Comparative study of the ORR activity of these materials in alkaline solution was performed using rotating disk electrode voltammetry. The experiments evidenced that, compared to non-doped OMC, charge transfer kinetics was improved independently on the nature of the heteroatom. The decrease of the ORR overvoltage and the increase of the mass activity upon doping are similar for B and P and less prominent for N. On the other hand, OMCs doped with low levels of B and N were found to be selective for O-2 reduction to peroxide, while for P-doped OMCs, the apparent number of electrons consumed per O-2 molecule was up to 3.1. Experimental measurements were complemented by density functional theory (DFT) calculations.

In this paper a new electrochemical method for determination of the β-carboline alkaloids, harmalol and harmine, using differential pulse voltammetry is presented. Experimental parameters such as pH, scan rate, pulse amplitude and pulse time were optimized to characterize their electrochemical behavior and to find best analytical conditions. Thus, in the presence of ascorbic acid, uric acid, dopamine, the developed method exhibits excellent performance for the determination of harmalol and harmine for a linear concentration range between 1–50 μM and 1–75 μM with a detection limit of 0.6 μM and 0.2 μM, respectively. The proposed method was successfully applied for the determination of these alkaloids in a sample of an Ayahuasca liana (Banisteriopsis caapi) and in model human urine samples with good recoveries.

Microwave-hydrothermal method was used for the synthesis of TiO2 and TiO2 doped with zirconium. The method was fast and simple and adsorbents were used for removal of As(III) and As(V) from aqueous solutions. The adsorbents were characterized by BET surface area measurements and powder XRD. Experiments showed that TiO2 doped with 10% of Zr using the microwave-hydrothermal method have greater specific surface area and total pore volume in comparison with TiO2 synthesized using the same method. Better removal with doped adsorbent was obtained for both, As(III) and As(V). Further experiments were carried out with Zr doped TiO2 sorbent in order to examine kinetic of adsorption, influence of pH and effect of common anions present in natural waters. (C) 2014 King Saud University. Production and hosting by Elsevier B.V. All rights reserved.

We report a novel, simple, rapid and sensitive electrochemical method for the determination of sulcotrione, a member of the relatively new class of triketone herbicides, using differential pulse voltammetry on a glassy carbon electrode. Its electrochemical behavior including influences of electrolyte composition, pH and scan rate was studied to select optimal experimental parameters for its determination. In Britton-Robinson buffer at pH 3 sulcotrione provided a well-defined reduction peak at -0.84 V (vs. Ag/AgCl electrode), with good repeatability (relative standard deviation of 2.3% for 8 measurements at 10 mu M concentration level). With optimized parameters differential pulse voltammetry rendered two linear concentration ranges from 0.2 to 2 mu M and from 2 to 50 mM with a detection limit of 0.05 mu M. The proposed procedure was successfully applied to the determination of sulcotrione in spiked river water samples with satisfactory recoveries (93-109%). The developed method may represent a simple, rapid and sensitive alternative to highly toxic mercury electrodes and chromatographic methods. Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3419]

The application of various electrodes for in situ degradation of Reactive Yellow 125 (RY125) and Reactive Green 15 (RG15) dyes, as well as ecotoxicity screening test of their degradation products were studied in this paper. The degradation process was performed in a two-electrode cylindrical cell, with Fisher platinum electrode as anode and Pd, Zr, or C electrodes as cathode; in 0.1 M Na2SO4 as supporting electrolyte. The optimal conditions (voltage and pH value) for degradation were determined in a platinum-palladium (Pt-Pd) model system for 200 mg/L of both reactive dyes. Then the electrolysis with other electrodes was conducted under the same conditions. Decolorization was monitored spectrofotometrically (UV-Vis) and the degradation efficiency was confirmed by HPLC technique with a DAD detector. Differences in degradation efficiency were observed between these three electrochemical systems (Pt-Pd, Pt-Zr, and Pt-C). The Pt-Pd system was the most efficient for the degradation of both reactive dyes. Achieved decolorization percentage for RG15 and RY125 were 98% and 97%, respectively. The ecotoxicity assessment of degradation products was performed using Anemia sauna. Toxicity data were compared by Kruskal-Wallis one-way analysis and pair-wise group comparisons with Mann-Whitney U tests. Statistically significant differences (p LT 0.05) in mortality (%) for Pt-Pd and Pt-Zr systems were determined between treated and untreated dye solutions of RG15. System Pt-C had no detectable significance in treatment of solutions of both dyes.

Efficiency of Fe2O3 and mixture of Fe2O3 and MnO2 nanoparticles synthesised by mechanical–chemical reaction for inorganic As(III) and As(V) sorption was examined. Sorbents (Fe2O3 and mixture Fe2O3:MnO2 = 3:1) synthesised by mechanical–chemical treatment in planetary ball mile with different milling times were tested by batch experiments. Experimental data were fitted both to Freundlich and Langmuir adsorption models. Efficiency of sorption was in good correlation with the time of milling in case of pure oxide. There were small differences in sorption between As(III) and As(V). In the case of mixture of oxides results were different. The best results were obtained by 30 min of milling. With prolonged milling, the sorption decreased to 3 h and after that increased again. These results were explained by phase transition. Sorption kinetics, influence of pH and the presence of other anions were examined for mixture of oxides with highest sorption capacity. The bioavailability of sorbed arsen was tested using modified Tessier procedure.

Elevated concentrations of arsenic in groundwater, which is used as a source for drinking water, is a worldwide problem. Use of TiO2 and iron doped TiO2 synthesized by a microwave-assisted hydrothermal method for As(III) and As(V) removal were examined. Synthesized sorbents were characterized with XRD and nitrogen physisorption. Synthesized sorbents have predominantly anatase structure, and no peaks for iron could be observed. Doping of iron increases the surface area of synthesized sorbents. Sorption experiments show that increase of iron in sorbents increases the sorption capacity for As(III) and As(V). Increase of pH from 3 to 11 has no influence on As(III) sorption but decreases the sorption of As(V). Batch isotherm studies were performed to determine the binding capacities of As(III) and As(V). As(III) followed the Freundlich isotherm model, while for As(V) a better fit was with the Langmuir isotherm. The results of competition of SO42- and PO43- anions on adsorption of As(III) indicated that both anions reduced substantially the efficiency of adsorption on both adsorbents while for As(V) only the presence of PO43- anion interfered with adsorption. Testing 10Fe/TiO2 sorbent with arsenic contaminated natural water showed that this material could be used for removal of arsenic to the level recommended by WHO without pretreatment.

Bentonite clay rich in smectite clay mineral from seldom investigated locality Mecji Do (MD) in Serbia was modified. The organomodification was performed with different loadings of benzyltrimethylammonium (BTMA) cation. The characterization of clay-based samples was performed, including XRD, FTIR and chemical and textural analysis. Electrochemical investigation was performed on a glassy carbon electrode (GCE) support with thin film of homogenously deposited either Na-enriched or one of organomodified clays forming composite electrodes. The behavior of the composite electrodes in the electrooxidation of p-nitrophenol (p-NP) in acidic media was analyzed using multisweep cyclic voltammetry. Oxidation of p-NP occurred at 1.2 V vs. Ag/AgCl for all investigated electrodes. The results indicate that the incorporation of BTMA cations into smectite enhanced the electrode stability toward the electrooxidation of p-NP in comparison to bare GCE and composite electrode based on Na-enriched clay. The current density for the p-NP oxidation wave slightly decreased with the increase of BTMA loading. On the other hand the electrode stability was significantly improved with the increase of BTMA loading. This is the peer-reviewed version of the article: M.J. Zunic, A.D. Milutinovic-Nikolic, D.M. Stankovic, D.D. Manojlovic, N.P. Jovic-Jovicic, P.T. Bankovic, Z.D. Mojovic, D.M. Jovanovic, Electrooxidation of ´ p-nitrophenol using a composite organosmectite clay glassy carbon electrode, Applied Surface Science (2014), [http://dx.doi.org/10.1016/j.apsusc.2014.05.228] [http://cer.ihtm.bg.ac.rs/handle/123456789/1576]

A sensitive, selective and reliable electrochemical method for the determination of nicotine using differential pulse voltammetry on a bare boron-doped diamond electrode has been developed. Nicotine yielded a single oxidation peak at a highly positive potential of +1.45 V (vs. Ag/AgCl/3 M KCl) in Britton-Robinson buffer solution at pH 8. The influence of supporting electrolyte, pH and scan rate on the current response of NIC was investigated. At optimized experimental conditions, a linear relation between peak current and concentration of nicotine was found for the range from 0.5 to 200 mu M (0.08-32.9 mg L-1) with a detection limit of 0.3 mu M (0.05 mg L-1) and a good repeatability (relative standard deviation of 2.1% at 25 mu M concentration level, n = 10) was achieved without any electrode surface modification. The practical usefulness of the developed procedure was successfully demonstrated with the determination of nicotine in tobacco products and anti-smoking pharmaceuticals with results similar to those obtained by a high-performance liquid chromatography and to the contents declared by the manufacturer, respectively. Prior to analysis, the sample pretreatment includes only sonication and/or simple liquid-liquid extraction. The proposed sensor represents an effective electrochemical tool and a promising alternative for quality control analysis of products in tobacco and pharmaceutical industry. (C) 2013 Elsevier B.V. All rights reserved.

This paper describes the preparation of a new sensor based on Zn-ferrite modified glassy carbon paste electrode and its electrochemical application for the determination of trace Cd(II) ions in waste waters using differential pulse anodic stripping voltammetry (DPASV). Different Zn/Ni ferrite nanoparticles were synthesized and characterized using scanning electron microscopy (SEM) and X-ray powder diffraction (XRPD). The prepared ferrite nanoparticles were used for the preparation of Zn-ferrite-modified glassy carbon paste electrode (ZnMGCPE) for determination of Cd(II) at nanomolar levels in waste water at pH 5. The different parameters such as conditions of preparation, Zn2+/Ni2+/Fe2+ ratio and electrochemical parameters, percentage of modifier, accumulation time, pH and accumulation potential were investigated. Besides, interference measurements were also evaluated under optimized parameters. The best voltammetric response was observed for ZnFe2O4 modifier, when the percentage of modifier was 3 %, accumulation time 9 min, pH of supporting electrolyte 5 and accumulation potential −1.05 V. Thus prepared electrode displays excellent response to Cd(II) with a detection limit of 0.38 ppb, and selective detection toward Cd(II) was achieved.

Degradation of two triketone herbicides, mesotrione and sulcotrione, was studied using four different advanced oxidation processes (AOPs): ozonization, dielectric barrier discharge (DBD reactor), photocatalysis and Fenton reagent, in order to find differences in mechanism of degradation. Degradation products were identified by high performance liquid chromatography (HPLC–DAD) and UHPLC–Orbitrap–MS analyses. A simple mechanism of degradation for different AOP was proposed. Thirteen products were identified during all degradations for both pesticides. It was assumed that the oxidation mechanisms in the all four technologies were not based only on the production and use of the hydroxyl radical, but they also included other kinds of oxidation mechanisms specific for each technology. Similarity was observed between degradation mechanism of ozonation and DBD. The greatest difference in the products was found in Fenton degradation which included the opening of benzene ring. When degraded with same AOP pesticides gave at the end of treatment the same products. Global toxicity and COD value of samples was determined after all degradations. Real water sample was used to study influence of organic matter on pesticide degradation. These results could lead to accurate estimates of the overall effects of triketone herbicides on environmental ecosystems and also contributed to the development of improved removal processes.

The determination of Pb and Cd with a Nafion-modified glassy carbon electrode and Cu-DPABA complex (Cu-DPABA NA/GCE; DPABA is methyl 3,5-bis{bis-[(pyridin-2-yl)methyl]amino}methyl-benzoate) as an alternative electrode for anodic stripping voltammetry was described. Pb and Cd were accumulated in acetate buffer pH 4 at a potential of -1.4 V (vs. Ag/AgCl electrode) for 120 s followed by a DPASV scan from -1.2 to -0.2 V. Under optimum conditions the calibration curves were linear in the range of 4.8 x 10(-9)-5.0 x 10(-5) and 5.0 x 10(-9)-5 x 10(-5) molL(-1) for Pb and Cd, respectively. Detection limits were 1.8 x 10(-9) and 1.2 x 10(-9) mol L(-1) for Pb and Cd, respectively. Different parameters and conditions, such as membrane ingredients, accumulation time, potential and pH value were optimized. A study of interfering substances was also performed. A significant increase in current was achieved at the modified electrode in comparison with the bare glassy carbon electrode. The validation of the proposed method was made by Pb and Cd determination in the certified reference material Groundwater CRM 610 (BCR, Community Bureau of Reference, Brussels, Belgium). The electrode was successfully applied for determination of Pb and Cd in river water with a high content of organic contaminants without any pretreatment.