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Made available in DSpace on 2022-04-28T19:41:00Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-10-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Most of commercial WLEDs have a lack of red-emission component resulting in cool white illumination. Aiming this issue, in this paper, we present the synthesis of [Eu(salen)2] with a Schiff base type ligand, the salen (N,N′-ethylene-bis(salicylidenimine)), another lanthanide complex was also investigated, the [Gd(salen)2]. Both complexes were characterized by conventional spectroscopy techniques to confirm their preparation, and the free software LUMPAC was used as a friendly interface to determine the experimental intensity parameters (Ω2 and Ω4) for the Eu-complex, it was also used to optimize the complex structure, perform theoretical calculations of excited states, and intensity parameters. The Eu-complex was immobilized in PMMA films in different amounts, and their photophysics properties were analyzed. The 7.5 wt% doped film showed the best photophisical results (τ = 0.226 ms; ΦEuEu = 9.61%), and it was chosen to coat a UV LED-chip (λem = 400 nm ± 10 nm) to fabricate a red emissive LED-prototype; also, a prototype with a blend between powdered Eu-complex and cyanoacrylate glue was fabricated, and their emission behavior and radiant photostability were compared. The prototype with the doped PMMA film exhibited poorer radiant photostability than the powder prototype after 24 h of operation. Thus, the [Eu(salen)2] powder prototype gather some important characteristics to be used as a red component of warm WLEDs. São Paulo State University (Unesp) School of Technology and Sciences São Paulo State University (Unesp) Institute of Chemistry São Paulo State University (Unesp) Institute of Biosciences Humanities and Exact Sciences São Paulo State University (Unesp) School of Technology and Sciences São Paulo State University (Unesp) Institute of Chemistry São Paulo State University (Unesp) Institute of Biosciences Humanities and Exact Sciences CAPES: 1531833 FAPESP: 2015/03400–5 FAPESP: 2016/09017–1 FAPESP: 2019/26103–7 CNPq: 303282/2020–7 CNPq: 304003/2018–1 CAPES: 88887.341772/2019–00

This work aims to evaluate the behavior of the FTO/m-BiVO4 photoanode in different electrolytes, pH, anions and cations, in order to investigate the influence of these parameters on their photoelectrochemical activity. The m-BiVO4 semiconductor was developed by combustion synthesis in solution (SCS) and deposited by dip-coating technique on fluorinated doped tin oxide (FTO) coated glass substrate. The morphological and structural characterization of the film was performed by XRD, UV-Vis and SEM measurements. The evaluation of the photosensitive behavior of the film was made by linear voltammetry and chronoamperometry in the presence of pulsed visible light. After photoelectrochemical parameters optimization, the study of photoelectrocatalysis in glucose degradation was performed. Thus, it was possible to evaluate the efficiency of the film in the photoelectrocatalytic processes, presenting itself as a potential material for such applications.

To analyze the consumption of oxygen and to quantify the mitochondrial respiratory chain proteins (OXPHOS) in the gastrocnemius muscle of rats exposed to cigarette smoke and/or RT practitioners.Wistar rats were divided into groups: Control (C), Smoker (S), Exercise (E) and Exercise Smoker (ES). Groups F and ES were exposed to the smoke of 4 cigarettes for 30 min, 2× a day, 5× a week, for 16 weeks. Groups E and ES performed four climbs with progressive load, 1× per day, 5× per week, for 16 weeks. The gastrocnemius muscle was collected for analysis of OXPHOS content and oxygen consumption. Groups S (vs. C) and ES (vs. C and E) showed lower body weight gain when observing the evolution curve.The S rats showed a reduction in the NDUFB8 proteins of complex 1, SDHB of complex 2, MTC01 of complex 4 and ATP5A of complex 5 (ATP Synthase) compared to Group C. Additionally, S rats also showed increased consumption of O2 in Basal, Leak, Complex I and I/II combined measures compared to the other groups, suggesting that the activity of the mitochondria of these animals increased in terms of coupling and uncoupling parameters.Our data suggest that exposure to cigarette smoke for 16 weeks is capable of causing impairment of mitochondrial function with reduced expression of respiratory chain proteins in skeletal muscle. However, the RT was effective in preventing impairment of mitochondrial function in the skeletal muscle of rats exposed to secondary cigarette smoke.

Made available in DSpace on 2021-06-25T10:31:57Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-06-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) The present study evaluated the spatiotemporal variation in concentration of cadmium, lead and copper ions in groundwater wells in the stratigraphic subdivision “Santo Anastácio” that belongs to the Bauru aquifer system in the western region of São Paulo State. Exploratory statistics methods were employed to investigate the response of the concentration of these metals in the aquifer through the pluviometric index of the region. The results show a direct dependence of the mean monthly flow of the metals in the groundwaters to the monthly rainfall flow. The observed behavior was cyclic with a gradual increase and decrease in the flow throughout time. Two groups of cyclic variation were identified. The seasonality of the mean monthly flow of Cd2+ and Pb2+ was inversely proportional to the magnitude of the pluviometric index of the region studied. Meanwhile, the seasonality of Cu2+ was directly correlated to the seasonable rainfall variability. These behaviors lead us to point out that cadmium and lead come from minerals present in the aquifer itself and the presence of copper in groundwater is associated with an anthropogenic action due to the region’s agricultural activity. The study helps us better comprehend the behavior of the whole groundwater system through a comparison with temporal hydrogeochemistry. Department of Chemistry and Biochemistry School of Science and Technology—Sao Paulo State University (UNESP), Rua Roberto Simonsen 305 Department of Chemistry and Biochemistry School of Science and Technology—Sao Paulo State University (UNESP), Rua Roberto Simonsen 305 FAPESP: 2013/07296‐2 CNPq: 301298/2017‐3

Made available in DSpace on 2021-06-25T10:18:21Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) We have developed electrocatalytic platforms based on palladium metallopolymer-graphene for the water splitting reaction. The platforms presented a low potential for the water oxidation reaction. By cyclic voltammetry and electrochemical impedance spectroscopy (EIS), the interfacial phenomena were investigated, allowing us to obtain important results that helped to determine kinetic and mechanistic information. The studies revealed that the introduction of graphene in the metallopolymer matrix increased the turnover frequency (TOF) value. Analysis of the Tafel plots obtained from the EIS data also revealed a change in the reaction mechanism after the introduction of graphene. The new platform demonstrated its applicability in the water splitting reaction for use in fuel cells. Department of Chemistry and Biochemistry School of Science and Technology - Sao Paulo State University (UNESP), Rua Roberto Simonsen 305 Department of Chemistry and Biochemistry School of Science and Technology - Sao Paulo State University (UNESP), Rua Roberto Simonsen 305 FAPESP: 2016/09017-1 CNPq: 301298/2017-3 CAPES: 88882.434480/2019-01

Made available in DSpace on 2020-12-12T01:21:50Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-04-22 The present paper describes the development of a novel photochemiresistor sensor for the determination of chemical oxygen demand (COD). A chemiresistive device was produced by a thin film of the monoclinic phase of bismuth vanadate deposited on an FTO glass surface. The resistive properties of the photosensor were carried out by electrochemical impedance spectroscopy (EIS). The electrical resistance of the platform was dependent on the presence of organic material in aqueous solution and the incidence of light. The decrease in resistance can be explained by considering that by increasing the amount of organic material, the amount of charge transferred to BiVO4 increases, as does the amount of the photogenerated conduction band on the film. This behavior is not observed when carrying out the same measurements in the absence of light. Under the optimal experimental conditions, the linear response of the chemiresistor sensor is between 0.20 and 19.9 mg L-1 COD at a fixed AC frequency of 0.1 Hz. There is a good correlation between the charge transfer resistance and COD concentration in the electrolyte solution. Quantification of COD in waste and lake waters was successfully performed using the novel photochemiresistor sensor. The results achieved in the analysis with the sensor are in accordance with the conventional method. Department of Chemistry and Biochemistry School of Science and Technology Sao Paulo State University (UNESP), Rua Roberto Simonsen, 305 CEP Department of Physics School of Science and Technology São Paulo State University (UNESP) Department of Chemistry and Biochemistry School of Science and Technology Sao Paulo State University (UNESP), Rua Roberto Simonsen, 305 CEP Department of Physics School of Science and Technology São Paulo State University (UNESP)

Made available in DSpace on 2018-12-11T17:21:56Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-12-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) A resistance detection device for dissolved molecular oxygen in aqueous solutions is prepared using a chemiresistor material as sensor platform. The chemiresistive circuit element is fashioned from a thin film of a cobalt-salen metallopolymer electrodeposited on a platinum electrode. Electrochemical impedance spectroscopy shows that the resistive and capacitive properties of the sensor platform depend on the presence of dissolved oxygen. The electrical circuit models are R(Q/R)(Q/R) and R(Q/R)(Q/RW) in the absence and presence of oxygen, respectively. The chemiresistor sensor exhibits good sensitivity (0.483 kΩ L mg−1), excellent reversibility and excellent linearity over a range of dissolved oxygen concentrations typically found under environmental conditions (2.72–40.9 mg L−1). The sensor fabricated in this work can potentially serve as an alternative sensor for the detection of dissolved oxygen in environmental samples. Department of Chemistry and Biochemistry School of Science and Technology - Sao Paulo State University (UNESP), Rua Roberto Simonsen 305, CEP 19060-900 Department of Chemistry and Biochemistry School of Science and Technology - Sao Paulo State University (UNESP), Rua Roberto Simonsen 305, CEP 19060-900 CNPq: 113827/2012-1 FAPESP: 2016/09017-1

Made available in DSpace on 2021-06-25T11:17:47Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-09-15 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) In the present study, we report the use of an electrochemical sensor for uric acid using a molecularly imprinted polymer (MIP) as a molecular recognition platform. The MIP was based on an azopolymer electropolymerized in the presence of uric acid used as a template molecule. The azo group of the polymer contributes to the quantifiable redox capacitance of the electrode surface, which can be probed by impedance/capacitance spectroscopy. Thus, the advantage of the developed sensor is its ability to perform direct measurements without a soluble redox probe. The molecularly imprinted polymer can sensitively transduce the recognition and binding of specific analytes by redox capacitance. Through electrochemical impedance spectroscopy (EIS) and electrochemical capacitive spectroscopy (ECS), unusual approaches were able to obtain different analytical curves with distinct characteristics, reaching a limit of detection of 0.160 μmol L−1. Department of Chemistry and Biochemistry School of Science and Technology – Sao Paulo State University (UNESP), Rua Roberto Simonsen 305 Department of Chemistry and Biochemistry School of Science and Technology – Sao Paulo State University (UNESP), Rua Roberto Simonsen 305 FAPESP: 2016/09017-1 CNPq: 301298/2017-3 CAPES: 88882.434480/2019-01

Made available in DSpace on 2018-12-11T16:46:12Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-09-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) The emission of radon gas in regions of geological faults, during the radioactive decay of uranium and thorium, results in the formation of lead isotopes 210Pb, 208Pb, 207Pb and 206Pb. As a consequence, the lead contamination in the soil poses a hazard to humans through ingestion of food, contaminated water, and even by direct contact with the soil contaminant. So far the relationship between the occurrence of geological faults and soil Pb contamination has not been established. Here, we studied lead in soils of regions with geological faults and their possible relationship with radon emissions. Soils were sampled from Presidente Prudente located in the far west of São Paulo State, Brazil. The region has strong evidence of the existence and direction of geological faults at depths of approximately 200 m. Soil sampling was done according to the USEPA 3050 method. Total lead was quantified by anodic stripping voltammetry. Results show that the total Pb concentration increases systematically with soil depth. This finding is explained by the fact that the lead originates from radon emissions. Pearson correlation analysis further proves a relationship of the nuclear track density obtained with CR-39 detectors, and mean Pb levels within each soil profile. Overall, our findings should improve risk evaluation of Pb contamination derived from radon emission and geological faults. Department of Chemistry and Biochemistry Faculty of Science and Technology São Paulo State University (UNESP) Department of Physics Faculty of Science and Technology São Paulo State University (UNESP) Department of Geography Faculty of Science and Technology São Paulo State University (UNESP) Department of Chemistry and Biochemistry Faculty of Science and Technology São Paulo State University (UNESP) Department of Physics Faculty of Science and Technology São Paulo State University (UNESP) Department of Geography Faculty of Science and Technology São Paulo State University (UNESP) CNPq: 234256/2014-1 CNPq: 302728/2012-0

Entidades de todo o mundo estão cada vez mais fortalecendo movimentos em prol de um planeta mais saudável e sustentável. Neste sentido, o intuito deste trabalho é a construção de nanofibras de C/BiVO4 via eletrofiação e posterior carbonização do polímero PVA. Obtendo assim, nanofibras com elevada área superficial quando comparados aos usais métodos de deposição. Possibilitando maior absorção dos fótons e consequentemente elevando a eficiência fotoeletrocatalítica na conversão energética e degradação de poluentes orgânicos. O BiVO4 sintetizado foi caracterizado e assim confirmado a formação da fase monoclínica. A técnica de eletrofiação apresentou fibras com diâmetros na escala nanométrica com a presença do carbono, aumentando consideravelmente a área superficial do material, confirmado pelas microscopias óptica e eletrônica de varredura.

No presente trabalho foi estudado o desenvolvimento de um polímero molecularmente impresso (PMI) baseado no poli(azo-Bismarck Y) para detecção de ácido úrico. O filme PMI foi preparado pela eletropolimerização do monômero Bismarck Brown Y na presença de ácido úrico como molécula molde sobre a superfície do eletrodo de óxido de estanho dopado com flúor (FTO). O sensor PMI-poli(azo-Bismark Y) exibiu boa resposta eletroquímica, alta sensibilidade e seletividade na ligação específica ao ácido úrico. Sob as condições experimentais otimizadas, a resposta voltamétrica do sensor proposto foi linear no intervalo de concentração de 0,20 mmol L-1 a 0,60 mmol L-1, com limite de detecção de 0,17 mmol L−1.

Made available in DSpace on 2022-04-28T19:30:18Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-05-20 The present work describes the performance of a new voltammetric sensor based on the modification of glassy carbon electrodes (GCE) with carbon black (CB) and botryosphaeran (BOT) (CB-BOT/GCE) for the electroanalytical determination of cyclobenzaprine. BOT is a fungal exocellular (1→3)(1→6)-β-ᴅ-glucan, which was used to improve the adherence of CB onto the surface of GCE. The electrochemical characterisation was performed by electrochemical impedance spectroscopy which showed an improvement in the transfer of electrons on the surface of the sensor developed in relation to the unmodified (bare) GCE. The voltammetric behaviour of cyclobenzaprine was studied using bare GCE, BOT/GCE, CB/GCE, and CB-BOT/GCE. All electrodes presented an oxidation peak (+ 1.0 V) for cyclobenzaprine, while the cyclobenzaprine peak intensity on CB-BOT/GCE was found to be 480% higher than the bare GCE. Through employing square-wave voltammetry, the analytical curve was found to be linear over the concentration range of 2.0 to 20.6 μmol L−1 (in 0.1 mol L−1 NaCl solution) with a detection limit (based on 3-sigma) of 0.63 μmol L−1. The developed electrochemical sensor exhibited excellent sensitivity and selectivity and was successfully applied for the voltammetric determination of cyclobenzaprine in pharmaceutical, biological, and environmental samples for the first time using the CB-BOT/GCE electrochemical sensing platform. Departamento de Química Centro de Ciências Exatas Universidade Estadual de Londrina, Rodovia Celso Garcia Cid, 445 Km 380 Faculty of Science and Engineering Manchester Metropolitan University, Chester Street Departamento de Química e Bioquímica Escola de Ciência e Tecnologia Universidade do Estado de São Paulo Programa de Pós-Graduação em Ciências Fisiológicas Departamento de Ciências Fisiológicas Centro de Ciências Biológicas Universidade Estadual de Londrina Beta-Glucan Produtos Farmoquímicos EIRELI UTFPR Câmpus Londrina, Lote 24A, Bloco Zircônia, Avenida João Miguel Caram 731

Made available in DSpace on 2018-12-11T16:43:01Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-01-01 Electropolymerization of a π-conjugated polymer from [N,N′-bis(salicylidene)-o-phenylenediamine]nickel(II) complex ([Ni(salophen)]) on the surface of indium-tin-oxide (ITO) was studied. Two structures of the polymer have been proposed based on the theorem of molecular columns. The highlighted structures are the molecular column of the central aromatic rings (MCCAR) and molecular column of the side aromatic rings (MCSAR). The molecular structures were obtained by control of the potential scan rate in the electropolymerization step. The MCCAR structures are stable and structurally compact, whereas the MCSAR structures are less compact. Electrochemical measurements, atomic force microscopy (AFM), UV–Vis spectroscopy, FTIR Raman spectroscopy and optical microscopy support the formation of the multiblock π-conjugated polymer. Department of Chemistry and Biochemistry Faculty of Science and Technology São Paulo State University (UNESP), Rua Roberto Simonsen 305 São Carlos Institute of Chemistry University of São Paulo (USP) Department of Chemistry Faculty of Science and Technology University of Coimbra Department of Chemistry and Biochemistry Faculty of Science and Technology São Paulo State University (UNESP), Rua Roberto Simonsen 305

Made available in DSpace on 2020-12-12T02:47:27Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-08-01 Exposure to secondhand cigarette smoke is associated with the development of diverse diseases. Resistance training has been considered one of the most useful tools for patients with pulmonary disease, improving their quality of life. This study aimed to evaluate the effect of resistance training (RT) on the prevention of thickening of the right ventricle wall of rats exposed to secondhand cigarette smoke. Thirty-two Wistar rats were divided into four groups: Control (C), Smoker (S), Exercised (E) and Exercised Smoker (ES). The smoker groups were exposed to the smoke of four cigarettes for 30 min, twice daily, five days a week, for 16 weeks. The exercised groups climbed on a vertical ladder with progressive load, once a day, five days a week, for 16 weeks. The heart, trachea, lung, liver and gastrocnemius muscle were removed for histopathological analysis. Pulmonary emphysema (S and ES vs C and E, P < 0.0001) and pulmonary artery thickness enlargement (S vs C and E, P = 0.003, ES vs C, P = 0.003) were detected in the smoking groups. There was an increase in the right ventricle thickness in the S group compared with all other groups (P < 0.0001). An increase in resident macrophages in the liver was detected in both smoking groups compared with the C group (P = 0.002). Additionally, a relevant reduction of the diameter of the muscle fibers was detected only in ES compared with the C, S and E groups (P = 0.0002), impairing, at least in part, the muscle mass in exercised smoking rats. Therefore, it was concluded that resistance training prevented the increase of thickness of the right ventricle in rats exposed to secondhand cigarette smoke, but it may be not so beneficial for the skeletal muscle of smoking rats. Department of Physiotherapy School of Sciences and Technology Sao Paulo State University (UNESP) Department of Pathology University of Western Sao Paulo UNOESTE Department of Chemistry and Biochemistry School of Sciences and Technology Sao Paulo State University (UNESP) Department of Physiotherapy School of Sciences and Technology Sao Paulo State University (UNESP) Department of Chemistry and Biochemistry School of Sciences and Technology Sao Paulo State University (UNESP)

The present research investigates the electrochemical behavior of a solar cell sensitized with Bismark Brown R azopolymer. This cell was developed from the electropolymerization of the dye on a conductive glass substrate coated with fluorine-doped tin oxide(FTO) by cyclic voltammetry. The photosensitive behavior of the obtained film was analyzed by cyclic voltammetry and chronoamperometry in the presence of pulsed light. The poly(azo-Bismarck R) exhibited reversible light-induced changes of electrical conductance, due to azo group photoisomerization. Electrochemical impedance spectroscopy was also carried out under a light source. This technique allowed to evaluate interfacial phenomena existing in the photovoltaic device, performing a Recebido em: 27/08/2018Aprovado em: 16/09/2018 52Colloquium Exactarum, v. 10, n.3,Jul-Set. 2018, p.51–65. DOI: 10.5747/ce.2018.v10.n3.e245detailed investigationof its photoelectrochemical properties. A decrease in electrical resistance was observed with the lightincidence on the polymer membrane indicating charge transfer to the polymer conduction band.Photo-responsive film of Bismarck Brown can be developed for advanced organic photovoltaic such as solar cells.

Made available in DSpace on 2018-12-11T16:52:14Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-04-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) In this study, we explore the fabrication and properties of a sensing electrochemical platform that is based on a novel 11-mercaptoundecyl-N′,N″,N‴-trimethylammonium hexacyanoferrate (MAH) and 6-(ferrocenyl)hexanethiol (FT)/glucose oxidase (GOx) on gold substrate. The hexacyanoferrate and ferrocene moieties that were immobilized on the gold surface were examined as electron transfer mediators with the oxidase glucose. The sensing platform, based on 11-mercaptoundecyl-N′,N″,N‴-trimethylammonium hexacyanoferrate (MAH) and 6-(ferrocenyl)hexanethiol (FT)/GOx modified gold electrode, shows the potential to work with two distinct mechanisms for electrochemical response. The hexacyanoferrate anion that was anchored at positive edge charge of the 11-mercaptoundecyl-N′,N″,N‴-trimethylammonium on the gold surface provided an efficient electron transfer. It was demonstrated that in the design of the GOx/MAH, the FT/Au electrode is facilitating the electron transfer from GOx toward the gold substrate. We believe that this study adds a new facet to nanobioelectronics with applications for biofuels and sensorial platforms. Department of Chemistry and Biochemistry School of Science and Technology Sao Paulo State University (UNESP), Rua Roberto Simonsen 305 São Carlos Institute of Chemistry University of São Paulo (USP) São Carlos Department of Physiotherapy School of Science and Technology Sao Paulo State University (UNESP) Department of Chemistry and Biochemistry School of Science and Technology Sao Paulo State University (UNESP), Rua Roberto Simonsen 305 Department of Physiotherapy School of Science and Technology Sao Paulo State University (UNESP) FAPESP: 2012/21703-7 CNPq: 234256/2014-1 CNPq: 302728/2012-0

Made available in DSpace on 2018-12-11T16:44:30Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-01-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) This work reports on the sol-gel synthesis of barium- and europium-doped silica xerogel and its use as an electrocatalytic sensor. Barium was chosen to assist the network framing and europium to provide electronic properties, including the Eu2+/Eu3+ redox process. The results from different molecular and structural techniques indicated that this xerogel is a composite material that combines a non-crystalline polymeric silica network with a high level of agglomeration and a low degree of reticulation formed by the hydrolysis and condensation of TEOS and M-O bonds (M = Ba2+ and/or Eu3+), whereas the oxygen atoms belong to the xerogel phase. The electrochemical behavior of the silica xerogel:Ba2+,Eu3+ with different amounts of Eu3+ under several different conditions was investigated. The electrochemical sensing platform showed a well-defined redox coupling with a formal potential of 0.06 V, assigned to europium redox sites in silicate. Electrocatalytic activity was observed with an increasing anodic peak current to the isoniazid oxidation, indicating that the electrochemical sensing platform designed here was successfully achieved. Faculdade de Ciências e Tecnologia UNESP Univ Estadual Paulista, Rua Roberto Simonsen, 305 Instituto de Biociências Letras e Ciências Exatas UNESP Univ Estadual Paulista, Rua Cristóvão Colombo, 2265 Instituto de Química de São Carlos Universidade de São Paulo-USP Faculdade de Ciências e Tecnologia UNESP Univ Estadual Paulista, Rua Roberto Simonsen, 305 Instituto de Biociências Letras e Ciências Exatas UNESP Univ Estadual Paulista, Rua Cristóvão Colombo, 2265

The preparation and electrochemical characterization of a nickel hydroxide modified nickel electrode as well as its behavior as electrocatalyst toward the oxidation of hydrochlorothiazide (HCTZ) were investigated. The electrochemical behavior of the modified electrode and the electrooxidation of HCTZ were explored using cyclic voltammetry. The voltammetric response of the modified electrode in the detection of HCTZ is based on the electrochemical oxidation of the Ni(II)/Ni(III) and a chemical redox process. The analytical parameters for the electrooxidation of HCTZ by the nickel hydroxide modified nickel electrode were obtained in NaOH solution, in which the linear voltammetric response was in the concentration range from 1.39 × 10−5 to 1.67 × 10−4 mol L−1 with a limit of detection of 7.92 × 10−6 mol L−1 and a sensitivity of 0.138 μA L mmol−1. Tafel analysis was used to elucidate the kinetics and mechanism of HCTZ oxidation by the modified electrode.

The supramolecular building blocks from a nickel(II) bisalphen-type complex have been reported. The conjugations through the bridge provide flexibility of the monomer in the electropolymerization stage. Thus, different structures can be obtained with the variation of electrochemical parameters used in the electropolymerization. The structural characterization and the electrochemical behavior in aqueous solution was also evaluated, which demonstrated that the electropolymerization mechanism was similar to that observed for the classical salen polymers, but the molecular organization onto the conductor substrate was different. The supramolecular structure of the polymeric film allows observation of the NiI/NiII and NiII/NiIII redox couples by differential pulse voltammetry. Thus, the comproportionation constant and Gibbs energy were calculated for the NiI/NiII redox couple. These characteristics make these polymers versatile materials in the field of supramolecular chemistry and materials science, in particular in applications as sensors, in electrocatalysts and for energy storage.

Made available in DSpace on 2020-12-12T01:40:46Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-11-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) The present paper describes a nonenzymatic chemiresistor sensor based on an azo-polymer and reduced graphene oxide (rGO) as a resistive platform for superoxide radical detection. The sensorial platform was prepared on layer-by-layer-assembled films of poly(azo-Bismarck Brown Y) and reduced graphene oxide by cyclic voltammetry. The nanocomposite film exhibited interesting synergetic properties based on the redox properties of the azo-polymer combined with the good electronic conductivity and stability of graphene. The electrical conductivity mechanism of the graphene-polymer was analyzed by electrochemical impedance and compared to that of an electrode coated with only polymer. The conductance properties of the interlayer formed by π-π stacking between the conjugated structure of the polymer chains and the structure of the graphene sheet are dependent on the applied potential of the system. The performance of the poly(azo-BBY)/rGO film as a chemiresistor material for the sensing of superoxide anions was evaluated by impedance measurements at the applied potential of +0.30 in PBS (7.4). The charge transfer resistance values change substantially in the presence of superoxide in solution. The effect of superoxide on the resistivity of the device is attributed to changes in the oxidation state of the polymer. The impedance measurements in real time (chrono-impedance) with the poly(azo-BBY)/rGO sensor with different superoxide concentrations revealed good linearity behavior between the real impedance and the superoxide anion concentration (0.12–2.6 ​mmol ​L−1) with a detection limit of 81.0 μmol L−1. Department of Chemistry and Biochemistry School of Science and Technology - Sao Paulo State University (UNESP) Rua Roberto Simonsen 305 Department of Physiotherapy School of Science and Technology - Sao Paulo State University (UNESP) Presidente Prudente Department of Chemistry and Biochemistry School of Science and Technology - Sao Paulo State University (UNESP) Rua Roberto Simonsen 305 Department of Physiotherapy School of Science and Technology - Sao Paulo State University (UNESP) Presidente Prudente

An amperometric glucose biosensor based on on hexacyanoferrate 11-mercaptoundecyl- N’,N”,N”’ -trimethylammonium (HMA)/6-(ferrocenyl)hexanethiol (FT)/GOx modified gold electrode was fabricated and evaluated. The GOx/HMA/FT/Au electrode was characterized using cyclic voltammetry (CV) and used for glucose concentration estimation in standard solutions using CV and amperometric techniques.

Made available in DSpace on 2018-12-11T16:42:04Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-07-02 This article explores the assessment of atmospheric deposition, from the analysis of the sampling methods, the analytical procedures for chemical characterisation of pollutants, and the main results from the scientific literature. Atmospheric particulate matter (PM) was collected in four regions of the city of Presidente Prudente (Sao Paulo State, Brazil) characterised by heavy traffic flows and high population density. The Cd, Pb, and Cu metals were determined in samples using differential pulse anodic stripping voltammetry. The PM was collected every fortnight using passive sampling, over a total period of two years. A comparative study between the element deposition fluxes in four sampling sites was performed. The relative contribution of the quantitative descriptors to divergence among the analysis by Tocher grouping method was also studied. Department of Chemistry and Biochemistry Faculty of Sciences and Technology Sao Paulo University State (UNESP) Department of Chemistry and Biochemistry Faculty of Sciences and Technology Sao Paulo University State (UNESP)

Made available in DSpace on 2018-12-11T16:40:46Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-06-02 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) In this paper, we report the construction of an electrochemical sensing platform based on platinum nanoparticles supported on carbon (PtNPs/C) for the determination of the antibiotic tetracycline (TTC). Initially, the PtNPs/C was synthesized and characterized by powder X-ray diffraction spectroscopy and transmission electron microscopy. The effect of experimental parameters on the electrochemical behavior of the PtNPs/C coated glassy carbon electrode (PtNPs/C/GCE), including the amount of PtNPs and electroactive area, scan rate and pH, were evaluated. The electrooxidation of TTC on the PtNPs/C/GCE was investigated by cyclic voltammetry and differential pulse voltammetry, with the determination of TTC electrooxidation mechanism. Under optimum experimental conditions, the linear calibration range, detection limit, quantification and sensitivity of the PtNPs/C/GCE were 9.99-44.01 μmol L-1, 4.28 μmol L-1, 14.3 μmol L-1 and 3.32 μA L μmol-1 cm-2, respectively. Finally, the proposed electrochemical sensing platform was successfully applied to determine low TTC concentrations in urine samples, suggesting its great applicability in clinical analysis and quality control. São Carlos Institute of Chemistry University of São Paulo (USP) Faculty of Science São Paulo State University (UNESP) Faculty of Science and Technology São Paulo State University (UNESP) Faculty of Science São Paulo State University (UNESP) Faculty of Science and Technology São Paulo State University (UNESP) CNPq: 302728/2012-0

Made available in DSpace on 2013-09-27T14:53:52Z (GMT). No. of bitstreams: 1 WOS000288227800090.pdf: 442251 bytes, checksum: b5dc8c3fb00f96f187e4b8aba1393341 (MD5) Previous issue date: 2011-02-01 Made available in DSpace on 2013-09-30T18:09:39Z (GMT). No. of bitstreams: 1 WOS000288227800090.pdf: 442251 bytes, checksum: b5dc8c3fb00f96f187e4b8aba1393341 (MD5) Previous issue date: 2011-02-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T13:23:13Z No. of bitstreams: 1 WOS000288227800090.pdf: 442251 bytes, checksum: b5dc8c3fb00f96f187e4b8aba1393341 (MD5) Made available in DSpace on 2014-05-20T13:23:13Z (GMT). No. of bitstreams: 1 WOS000288227800090.pdf: 442251 bytes, checksum: b5dc8c3fb00f96f187e4b8aba1393341 (MD5) Previous issue date: 2011-02-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) The participation of cations in redox reactions of manganese oxides provides an opportunity for development of chemical sensors for non-electroactive ions. This paper describes the amperometric determination of lithium ions using carbon-paste electrode modified with spinel manganese(IV) oxide under flow conditions. Systematic investigations were made to optimize the experimental parameters for lithium sensor by flow injection analysis. The detection was based on the measurement of anodic current generated by oxidation of Mn(III) to Mn(IV) at the surface of the electrode and consequently the lithium ions extraction into the spinel structure. An operating potential of 0.50 V (vs. Ag/AgCl/3 KCl mol/L) was exploited for amperometric monitoring. The amperometric signal was linearly dependent on the lithium ions concentration over the range 4.0 x 10(-5) to 1.0 x 10(-3) mol L-1. The equilibrium constant of insertion/extraction of the lithium ion in the spine! structure, apparent Gibbs energy of insertion, and surface coverage of the electrode with manganese oxide, were calculated by peak charge (Q) in different concentration under flow conditions. Considering selectivity, the peak charge of the sensor was found to be linearly dependent on the ionic radius of the alkaline and earth-alkaline cations. (C) 2010 Elsevier Ltd. All rights reserved. Univ State São Paulo UNESP, Fac Sci & Technol, Dept Phys Chem & Biol, BR-19060900 Presidente Prudente, SP, Brazil Universidade Federal do Paraná (UFPR), Dept Quim, BR-80060000 Curitiba, Parana, Brazil Universidade Federal de São Carlos (UFSCar), Dept Quim, BR-13560 São Carlos, SP, Brazil Univ State São Paulo UNESP, Fac Sci & Technol, Dept Phys Chem & Biol, BR-19060900 Presidente Prudente, SP, Brazil FAPESP: 08/07298-7 FAPESP: 09/11079-1 CNPq: 474367/2004-5

The preparation and electrochemical characterization of a carbon paste electrode modified with layered birnessite-type manganese oxide for use as a sodium sensor is described. The effects of powder synthesis process (sol–gel and redox precipitation) for birnessite on the electrochemical activity of the sensor was investigated by cyclic voltammetry. The carbon paste electrode modified with birnessite-type manganese oxide that was synthesized by the sol–gel method showed a best electrochemical for sodium ions. The detection is based on the measurement of anodic current generated by oxidation of Mn(III) to Mn(IV) at the surface of the electrode and consequently the sodium ions extraction into the birnessite structure. The best voltammetric response was obtained for an electrode composition of 15% (w/w) birnessite oxide in the paste, a TRIS buffer solution of pH 8.0 and a scan rate of 50 mV s −1 . A sensitive linear voltammetric response for sodium ions was obtained in the concentration range of 7.89 × 10 −5 to 3.49 × 10 −4 mol L −1 with a slope of 37.5 μA L mmol −1 and a detection limit (3 σ /slope) of 3.43 × 10 −5 mol L −1 using cyclic voltammetry. Under the working conditions, the proposed method was successfully applied to determination of sodium ions in urine samples.

Made available in DSpace on 2013-09-27T14:53:53Z (GMT). No. of bitstreams: 1 WOS000275995600210.pdf: 171567 bytes, checksum: 8603747737628bbd5ef1b702ec0f6a96 (MD5) Previous issue date: 2009-01-01 Made available in DSpace on 2013-09-30T18:09:38Z (GMT). No. of bitstreams: 1 WOS000275995600210.pdf: 171567 bytes, checksum: 8603747737628bbd5ef1b702ec0f6a96 (MD5) Previous issue date: 2009-01-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T13:23:13Z No. of bitstreams: 1 WOS000275995600210.pdf: 171567 bytes, checksum: 8603747737628bbd5ef1b702ec0f6a96 (MD5) Made available in DSpace on 2014-05-20T13:23:13Z (GMT). No. of bitstreams: 1 WOS000275995600210.pdf: 171567 bytes, checksum: 8603747737628bbd5ef1b702ec0f6a96 (MD5) Previous issue date: 2009-01-01 An amperometric dipyrone sensor based on a polymeric nickel-salen (salen = N,N'-ethylenebis(salicydeneiminato)) film coated platinum electrode was developed. The sensor was constructed by electropolymerization of nickel-salen complex at a platinum electrode in acetonitrile/tetrabuthylamonium perchlorate by cyclic voltammetry. After cycling the modified electrode in a 0.50 mol L-1 KCl solution, the estimated surface concentration was found to be equal to 1.29 x 10(-9) mol cm(-2). This is a typical behavior of an electrode surface immobilized with a redox couple that can usually be considered as a reversible single-electron reduction/oxidation of the nickel(II)/nickel(III) couple. A plot of the anodic current versus the dipyrone concentration for chronoamperometry (potential fixed = +0.50 V) at the sensor was linear in the 4.7 x 10(-6) to 1.1 x 10(-4) mol L-1 concentration range and the concentration limit was 1.2 x 10(-6) mol L-1. The proposed electrode is useful for the quality control and routine analysis of dipyrone in pharmaceutical formulations. Univ State São Paulo UNESP, Dept Phys Chem & Biol, Fac Sci & Technol, Presidente Prudente, SP, Brazil Univ State São Paulo UNESP, Dept Phys Chem & Biol, Fac Sci & Technol, Presidente Prudente, SP, Brazil

Made available in DSpace on 2013-08-28T14:10:25Z (GMT). No. of bitstreams: 1 WOS000270213300002.pdf: 658881 bytes, checksum: 1f5c5299c22dcb801bcf602d01e6372e (MD5) Made available in DSpace on 2013-09-30T18:09:28Z (GMT). No. of bitstreams: 2 WOS000270213300002.pdf: 658881 bytes, checksum: 1f5c5299c22dcb801bcf602d01e6372e (MD5) WOS000270213300002.pdf.txt: 32167 bytes, checksum: b40a80e74296d8f79f86715cebe81471 (MD5) Previous issue date: 2009-09-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T13:23:09Z No. of bitstreams: 2 WOS000270213300002.pdf: 658881 bytes, checksum: 1f5c5299c22dcb801bcf602d01e6372e (MD5) WOS000270213300002.pdf.txt: 32167 bytes, checksum: b40a80e74296d8f79f86715cebe81471 (MD5) Made available in DSpace on 2014-05-20T13:23:09Z (GMT). No. of bitstreams: 2 WOS000270213300002.pdf: 658881 bytes, checksum: 1f5c5299c22dcb801bcf602d01e6372e (MD5) WOS000270213300002.pdf.txt: 32167 bytes, checksum: b40a80e74296d8f79f86715cebe81471 (MD5) Previous issue date: 2009-09-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) The participation of cations in redox reactions of manganese oxides provides an opportunity for development of chemical sensors for non-electroactive ions. A sensor based on a nanostructured hollandite-type manganese oxide was investigated for voltammetric detection of potassium ions. The detection is based on the measurement of anodic current generated by oxidation of Mn(III) to Mn(IV) at the surface of the electrode and the subsequent extraction of the potassium ions into the hollandite structure. In this work, an amperometric procedure at an operating potential of 0.80 V (versus SCE) is exploited for amperometric monitoring. The current signals are linearly proportional to potassium ion concentration in the range 4.97 x 10(-5) to 9.05 x 10(-4) mol L(-1), with a correlation coefficient of 0.9997. Univ State São Paulo, UNESP, Fac Sci & Technol, Dept Phys Chem & Biol, BR-19060900 Presidente Prudente, SP, Brazil Univ Fed Sao Carlos, Dept Quim, BR-13560 Sao Carlos, SP, Brazil Univ State São Paulo, UNESP, Fac Sci & Technol, Dept Phys Chem & Biol, BR-19060900 Presidente Prudente, SP, Brazil CNPq: 372010/2006-7

Made available in DSpace on 2018-12-11T16:38:42Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-06-25 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Abstract This paper describes the development of a selective lithium ion sensor based on spinel-type manganese oxide doped with gallium and anions (Ga0.02Mn1.98O3.98X0.02, where X = S2- and F-). Investigation was made of the influence of cationic and/or anionic doping agents on the potentiometric response of the sensor. Experimental parameters evaluated included the effect of the lithium concentration on activation of the sensor by cyclic voltammetry, the pH of the electrolyte solution, and the selectivity towards Li+ compared to other alkali and alkaline-earth metal ions. There was an important influence of the unit cell size of the material on the linear range, detection limit, and selectivity of the sensor. Reduction in the size of the tunnel for insertion of the lithium in the porous structure of the oxide directly affected the potentiometric performance of the electrode. Sensor performance increased in the order: Ga0.02Mn1.98O4 > Ga0.02Mn1.98O3.98S0.02 > Ga0.02Mn1.98O3.98F0.02. The observed super-Nernstian response could be explained by a mixed potential arising from two equilibria (redox and ion exchange) in the spinel-type manganese oxide. Sensitivity and the influence of pH on the electrode response were directly related to the doping agents present in the oxide structure. Faculty of Science and Technology, São Paulo State University (UNESP) Department of Chemistry, Federal University of Sao Carlos Faculty of Science and Technology, São Paulo State University (UNESP) FAPESP: 2005/01296-4 FAPESP: 474367/2004-5

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T18:48:34Z No. of bitstreams: 1 S0100-40422005000500017.pdf: 181681 bytes, checksum: 22c1b5ef47ac6301b4e78aace8b41c89 (MD5) Made available in DSpace on 2013-08-22T18:48:34Z (GMT). No. of bitstreams: 1 S0100-40422005000500017.pdf: 181681 bytes, checksum: 22c1b5ef47ac6301b4e78aace8b41c89 (MD5) Previous issue date: 2005-10-01 Made available in DSpace on 2013-09-30T19:38:33Z (GMT). No. of bitstreams: 2 S0100-40422005000500017.pdf: 181681 bytes, checksum: 22c1b5ef47ac6301b4e78aace8b41c89 (MD5) S0100-40422005000500017.pdf.txt: 22045 bytes, checksum: 49cbc2205ffc8d4b35b4068063304409 (MD5) Previous issue date: 2005-10-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T15:10:20Z No. of bitstreams: 2 S0100-40422005000500017.pdf: 181681 bytes, checksum: 22c1b5ef47ac6301b4e78aace8b41c89 (MD5) S0100-40422005000500017.pdf.txt: 22045 bytes, checksum: 49cbc2205ffc8d4b35b4068063304409 (MD5) Made available in DSpace on 2014-05-20T15:10:20Z (GMT). No. of bitstreams: 2 S0100-40422005000500017.pdf: 181681 bytes, checksum: 22c1b5ef47ac6301b4e78aace8b41c89 (MD5) S0100-40422005000500017.pdf.txt: 22045 bytes, checksum: 49cbc2205ffc8d4b35b4068063304409 (MD5) Previous issue date: 2005-10-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) The construction and analytical evaluation of a coated graphite-epoxy electrode sensitive to the zinc-1,10-phenantroline complex based on the [Zn(fen)3][tetrakis(4-chlorophenyl)borate]2 incorporated into a poly(vinylchloride) (PVC) matrix are described. A thin membrane film of this ion-pair, dibutylphthalate (DBPh) and PVC were deposited directly onto an electrically conductive graphite-epoxy support located inside a Perspex® tube. The best PVC polymeric membrane contains 65% (m/m) DBPh, 30% (m/m) PVC and 5% (m/m) of the ion-pair. This electrode shows a response of 19.5 mV dec-1 over the zinc(II) concentration range of 1.0 x 10-5 to 1.0 x 10-3 mol L-1 in 1,10-phenantroline medium, at pH 6.0. The response time was less than 20 seconds and the lifetime of this electrode was more than four months (over 1200 determinations by each polymeric membrane). It was successfully used as an indicator electrode in the potentiometric precipitation titration of zinc(II) ions. Universidade Estadual Paulista Universidade Federal de São Carlos (UFSCar) Departamento de Química Universidade de São Paulo Instituto de Química de São Carlos Departamento de Química e Física Molecular Universidade Estadual Paulista

The preparation and electrochemical characterization of a carbon paste electrode modified with N,N'-ethylenebis(salicylideneiminato)oxovanadium(IV) complex ([VO(Salen)]) as well as its behavior as electrocatalyst toward the oxidation of dipyrone were investigated. The electrochemical behavior of the modified electrode and the electrooxidation of dipyrone were explored using cyclic voltammetry. The voltammetric response of the modified electrode is based on two reactions. One electrochemical related to the oxidation of the metallic center of the [VO(Salen)] and the other involving the chemical redox process involving the oxidized form of the complex and the reduced form of dipyrone. The best voltammetric response was observed for a paste composition of 25% (m/m) [VO(Salen)], KCl solution pH from 5.5 to 8.0 as the electrolyte and potential scan rate of 10 mV s-1 in the presence of dipyrone. A linear voltammetric response for dipyrone was obtained in the concentration range from 9.9 x 10-6 to 2.8 x 10-3 mol L-1, with a detection limit of 7.2 x 10-6 mol L-1. Among of several compounds tested as potential interference, only ascorbic acid presented some interference. The proposed electrode is useful for the quality control and routine analysis of dipyrone in pharmaceutical formulations. A preparação e a caracterização eletroquímica de um eletrodo de pasta de carbono modificado com o complexo N,N´-etilenobis(salicilidenoaminato) de oxovanádio(IV) ([VO(Salen)]), como também o seu comportamento eletrocatalítico na oxidação da dipirona foi investigado. O comportamento eletroquímico do eletrodo modificado e a eletrooxidação da dipirona foram estudados usando a voltametria cíclica. A resposta voltamétrica do eletrodo modificado é baseada em duas reações. Uma relacionada com a oxidação eletroquímica do centro metálico do complexo [VO(Salen)] e a outra que envolve o processo redox entre centro metálico do complexo oxidado e a dipirona. A melhor resposta voltamétrica foi observada para uma composição do eletrodo de 25% (m/m) [VO(Salen)] em solução eletrolítica de KCl para pH entre 5,5 a 8,0 e uma velocidade de varredura de 10 mV s-1 na presença de dipirona. Uma resposta voltamétrica linear para dipirona foi obtida no intervalo de concentração de 9,9 x 10-6 a 2,8 x 10-4 mol L-1, com um limite de detecção de 7,2 x 10-6 mol L-1. Entre os diversos compostos testados como interferente, somente o ácido ascórbico apresentou alguma interferência. O eletrodo proposto é útil para o controle de qualidade e a análise rotineira de dipirona em formulações farmacêuticas.

A copper(II) hexacyanoferrate(III) (CuHCF) modified carbon paste electrode was used for the electroanalytical determination of pyridoxine (vitamin B6) in pharmaceutical preparations, using cyclic voltammetry. Diverse parameters were investigated for the optimization of the sensor response, such as composition of the electrode, electrolytic solution, effect of pH, scan rate of potential and interferences. The optimum conditions were found at an electrode composition of 20% CuHCF, 55% graphite and 25% mineral oil (m/m) in an acetate buffer (pH 5.5) containing 0.05 mol L-1 of NaCl. The range of determination of pyridoxine was from 1.2 x 10-6 to 6.9 x 10-4 mol L-1. The procedure was successfully applied to the determination of vitamin B6 in formulation preparations. The CuHCF modified carbon paste electrode gave results comparable to those obtained using spectrophotometry. Um eletrodo de pasta de carbono modificado com o complexo de hexacianoferrato(III) de cobre(II) (CuHCF) foi utilizado na determinação eletroanalítica de piridoxina (vitamina B6) em formulações farmacêuticas usando voltametria cíclica. Diversos parâmetros, tais como: composição do eletrodo, melhor solução eletrolítica, efeito do pH, velocidade de varredura de potenciais e interferentes sobre a resposta do eletrodo modificado, foram estudados. As melhores condições foram encontrados para uma composição de eletrodo de 20% de CuHCF (m/m), 55% de grafite (m/m) e 25% óleo mineral (m/m) em tampão acetato (pH 5,5) contendo 0,05 mol L-1 de NaCl. O intervalo de concentração para determinação de piridoxina foi 1,2 x 10-6 a 6,9 x 10-4 mol L-1. O procedimento foi aplicado na determinação de vitamina B6 em formulações farmacêuticas e os resultados obtidos com o eletrodo de pasta de carbono modificado com CuHCF foram comparados com os de espectrofotometria.

A solid Fe2O3 based carbon-epoxy composite electrode was investigated for use as a potentiometric pH sensor. The electrode was constructed using a mixture of sulfated iron(III) oxide, carbon power, and epoxy resin, which was deposited directly onto a glass tube. The effect of composition (Fe2O3 , carbon and epoxy resin) on the electrode response and its calibration curve (mV/pH) were investigated. The analytical behavior of the electrode in acid–base titrations was compared with that of a glass electrode. A linear response from pH 1.7 to 12.2 with a slope of –39.7 ± 0.6 mV/pH (at 25°C) was observed.

A solid Fe2O3 based carbon-epoxy composite electrode was investigated for use as a potentiometric pH sensor. The electrode was constructed using a mixture of sulfated iron(III) oxide, carbon power, and epoxy resin, which was deposited directly onto a glass tube. The effect of composition (Fe2O3 , carbon and epoxy resin) on the electrode response and its calibration curve (mV/pH) were investigated. The analytical behavior of the electrode in acid–base titrations was compared with that of a glass electrode. A linear response from pH 1.7 to 12.2 with a slope of –39.7 ± 0.6 mV/pH (at 25°C) was observed.

A coated graphite-epoxy ion-selective electrode for iron(III), based on the ion-pair formed between [Fe(citrate)2]3- and the tricaprylylmethylammonium cation (Aliquat 336) in a poly(vinylchloride) (PVC) matrix has been constructed. A thin membrane film of this ion-pair, dibutylphthalate (DBPh) in PVC was deposited directly onto a Perspex® tube, which contained a graphite-epoxy conductor substrate. The coating solution was prepared by dissolving 30% (w/w) of PVC in 10 mL of tetrahydrofuran following addition of 65% (w/w) DBPh and 5% (w/w) of the ionic pair. The effect of pH, citrate concentration and some cations on the electrode response has been investigated. The E(mV) vs. log [Fe(citrate)2]3- electrode response was linear for iron(III) concentration from 1.0 x 10-3 mol/L to 1.0 x 10-1 mol/L in 1.0 mol/L citrate medium, with a slope of 19.3 ± 0.5 mV/decade and a useful lifetime of at least six months (more than 800 determinations for each polymeric membrane used). The detection limit was 7.5 x 10-4 mol/L and the relative standard deviation was less than 3% for a solution containing 5.0 x 10-3 mol/L of iron(III) (n = 10). The application of this electrode for iron(III) determination in samples of vitamin formulations is described. The results obtained with this procedure are in close agreement with those obtained using AA spectrophotometry (r = 0.9999). Construiu-se um eletrodo íon-seletivo de grafite-epoxi recoberto para Fe(III), baseado no par-iônico formado entre o ânion [Fe(citrato)2]3- e o cátion tricaprililmetilamônio (Aliquat 336) incorporado em uma matriz de PVC (cloreto de polivinila). Uma membrana fina foi preparada pela incorporação deste par-iônico, ftalato de dibutila (DBPh) em PVC e aplicados diretamente em um tubo Perspex® contendo o condutor de grafite-epoxi. A solução de recobrimento foi preparada pela dissolução de 30% (m/m) de PVC em 10 mL de tetraidrofurano seguido da adição de 65% (m/m) de plastificante DBPh e 5% (m/m) do par-iônico. Investigou-se o efeito do pH, concentração de citrato e de alguns cátions sobre a resposta do eletrodo. O eletrodo apresentou uma resposta linear para E(mV) vs. log[Fe(citrato)2]3- no intervalo de concentração de ferro(III) de 1,0 x 10-3 a 1,0 x 10-1 mol/L em meio de citrato 1,0 mol/L, uma inclinação de 19,3 ± 0,5 mV/década e um tempo de vida de pelos menos 6 meses (mais de 800 determinações por cada membrana polimérica usada). O limite de detecção foi 7,5 x 10-4 mol/L e o desvio padrão relativo foi menor de 3% para solução contendo 5,0 x 10-3 mol/L de Fe(III) (n = 10). A aplicação deste eletrodo na determinação de ferro em amostras de vitamina é descrito. Os resultados obtidos com esse procedimento estão em concordância com aqueles obtidos usando espectrofotometria de absorção atômica (r = 0,9999).

The preparation and electrochemical characterization of a carbon paste electrode modified with the N , N -ethylene- bis (salicyllideneiminato)oxovanadium (IV) complex ([VO(salen)]) as well as its application for ranitidine determination are described. The electrochemical behavior of the modified electrode for the electroreduction of ranitidine was investigated using cyclic voltammetry, and analytical curves were obtained for ranitidine using linear sweep voltammetry (LSV) under optimized conditions. The best voltammetric response was obtained for an electrode composition of 20% (m/m) [VO(salen)] in the paste, 0.10 mol L − 1 of KCl solution (pH 5.5 adjusted with HCl) as supporting electrolyte and scan rate of 25 mV s − 1 . A sensitive linear voltammetric response for ranitidine was obtained in the concentration range from 9.9 × 10 − 5 to 1.0 × 10 − 3 mol L − 1 , with a detection limit of 6.6 × 10 − 5 mol L − 1 using linear sweep voltammetry. These results demonstrated the viability of this modified electrode as a sensor for determination, quality control and routine analysis of ranitidine in pharmaceutical formulations.

Made available in DSpace on 2013-09-27T14:53:53Z (GMT). No. of bitstreams: 1 WOS000275995600209.pdf: 196067 bytes, checksum: 28e9cc15bcb9ac9fa20cb6cbf7be20c2 (MD5) Previous issue date: 2009-01-01 Made available in DSpace on 2013-09-30T18:09:38Z (GMT). No. of bitstreams: 1 WOS000275995600209.pdf: 196067 bytes, checksum: 28e9cc15bcb9ac9fa20cb6cbf7be20c2 (MD5) Previous issue date: 2009-01-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T13:23:13Z No. of bitstreams: 1 WOS000275995600209.pdf: 196067 bytes, checksum: 28e9cc15bcb9ac9fa20cb6cbf7be20c2 (MD5) Made available in DSpace on 2014-05-20T13:23:13Z (GMT). No. of bitstreams: 1 WOS000275995600209.pdf: 196067 bytes, checksum: 28e9cc15bcb9ac9fa20cb6cbf7be20c2 (MD5) Previous issue date: 2009-01-01 In the work described by this paper, we studied the development of a selective potassium ion sensor constituted of a carbon paste electrode modified (CPEM) with a novel KSr(2)Nb(2)O(15). The material KSr(2)Nb(2)O(15) is an oxide with the tetragonal tungsten bronze structure (TTB) type are in forefront both in the area of research as well as in industrial applications. The sensor response to potassium ions was linear in the concentration range 1.26 x 10(-5) at 1.62 x 10(-3) mol L(-1) (E (mV) = 32.7 + 51.1 log [K(+)]). The sensor based KSr(2)Nb(2)O(15), of the TTB-type presented very good potentiometric response, with a slope of 51.1 mV/dec (at 25 degrees C) and detection limit for the potassium ions of 7.27 x 10(-5) mol.L(-1) Univ State São Paulo UNESP, Dept Phys Chem & Biol, Fac Sci & Technol, Presidente Prudente, SP, Brazil Univ State São Paulo UNESP, Dept Phys Chem & Biol, Fac Sci & Technol, Presidente Prudente, SP, Brazil

A carbon paste electrode modified with copper(II) phosphate immobilized in a polyester resin (CuP-Poly) is proposed for voltammetric determination of L-ascorbic acid in pharmaceutical formulations. The modified electrode allows the detection of L-ascorbic acid at lower anodic potentials than observed at unmodified electrodes. Several parameters that can influence the voltammetric response of the proposed electrode such as carbon paste composition, pH, scan rate, and possible interference were investigated. The peak current was proportional to the concentration of ascorbic acid in the range 2.0 x 10(-5) to 3.2 x 10(-3) mol L(-1) with a detection limit of 1.0 x 10(-5) mol L(-1). The stability and repeatability of the electrode for the determination of L-ascorbic acid are also discussed. Amperometric response was also recorded for electrocatalytic oxidation of the L-ascorbic acid. Concentrations of the vitamin C in pharmaceutical formulations (tablets) measured using the modified electrode and a titrimetric method are in agreement at the 95% confidence level and within an acceptable range of error.

A systematic evaluation of a Fe2O3 graphite-epoxy tubular electrode was investigated through pH measurements in a single-channel flow injection system. The tubular electrode was obtained by deposition of a mixture of iron(III) oxide, graphite powder and epoxy resin into a hole previously made in the injection channel (of a polyuretane resin block). The effect of electrode composition and flow injection parameters (flow rate and injection sample volume) on the Fe2O3-tubular-electrode response was initially evaluated in quintuplicate (confidence level of 95%). The best potentiometric response (E/mV = 178.2 - 26.5 pH; r = 0.9995) was reached in the pH range 2 to 12 with an electrode composition in mass of 30% Fe2O3, 20% graphite and 50% epoxy resin, injection sample volume of 300 mL and a flow rate of 3.2 mL min-1. The frequency rate was 90 h-1 and a useful lifetime of at least six months (more than 2000 determinations) was obtained. Uma avaliação sistemática de um eletrodo tubular de Fe2O3 em grafite epóxi foi realizada através de medições de pH em um sistema de injeção em fluxo de linha única. O eletrodo tubular foi obtido pela deposição de uma mistura de óxido de ferro(III), pó de grafite e resina epóxi no interior de um orifício feito previamente no canal de injeção (de resina poliuretana). O efeito da composição do eletrodo e dos parâmetros do sistema de injeção em fluxo (vazão e volume amostra) sobre a resposta do eletrodo foram avaliados em quintuplicata (limite de confiança de 95%). A melhor resposta potenciométrica (E/mV = 178,2 - 26,5 pH; r = 0,9995) foi obtida no intervalo de pH de 2 a 12 com um eletrodo de composição em massa 30% de Fe2O3, 20% de grafite e 50% de resina epóxi, volume de injeção de amostra de 300 mL e vazão de 3,2 mL min-1. A frequência analítica foi 90 h-1 e um tempo de vida útil de pelo menos 6 meses (mais de 2000 determinações) foi obtido.

The [Mn4IVO5(terpy)4(H2O)2]6+ complex, show great potential for electrode modification by electropolymerization using cyclic voltammetry. The voltammetric behavior both in and after electropolymerization process were also discussed, where the best condition of electropolymerization was observed for low scan rate and 50 potential cycles. A study in glass electrode for better characterization of polymer was also performed. Electrocatalytic process by metal centers of the conducting polymer in H2O2 presence with an increase of anodic current at 0.85 V vs. SCE can-5 -4 -1 be observed. The sensor showed great response from 9.9 x 10to 6.4 x 10 mol Lconcentration range with a -5 -1 detection limit of 8.8 x 10 mol L, where the electrocatalytic mechanism was based on oxidation of H2O2 to H2O IV IIIIII IV with consequently reduction of Mnto Mn. After, the Mnions are oxidized electrochemically to Mnions.

An amperometric oxygen sensor based on a polymeric nickel-salen (salen = N, Ń -ethylene bis (salicydeneiminato)) film coated platinum electrode was developed. The sensor was constructed by electropolymerization of nickel- salen complex at a platinum electrode in acetonitrile/tetrabuthylamonium perchlorate by cyclic voltammetry. The voltammetric behavior of the modified electrode was investigated in 0.5 mol L -1 KCl solution in the absence and presende of molecular oxygen. A significant increased of cathodic peak current (at -0.20 vs. SCE) of the modified electrode with addition of oxygen to the solution was observed. This result shows that the nickel- salen film on the surface of the electrode promotes the reduction of oxygen. The reaction can be brought about electrochemically where in the nickel(II) complex is first reduced to a nickel(I) complex at the electrode surface. The nickel(I) complex then undergoes a catalytic oxidation by the oxygen molecular in solution back to the nickel(II) complex, which can then be electrochemically re-reduced to produce an enhancement of the cathodic current. The plot of the cathodic current versus the dissolved oxygen concentration for chronoamperometry (potential fixed = -0.20 V) at the sensor was linear in the concentration range of 3.95 to 9.20 mg L -1 with concentration limit of 0.17 mg L -1 O 2 . The modified electrode proposed is useful for the quality control and routine analysis of dissolved oxygen in commercial water and environmental water samples. The results obtained for the levels of dissolved oxygen are in agreement with the results obtained with an O 2 commercial sensor.

Made available in DSpace on 2013-09-27T14:53:53Z (GMT). No. of bitstreams: 1 WOS000295663600026.pdf: 153288 bytes, checksum: 0a1e1c45794cf17f3eaedd95db054ac6 (MD5) Previous issue date: 2011-11-01 Made available in DSpace on 2013-09-30T18:09:39Z (GMT). No. of bitstreams: 1 WOS000295663600026.pdf: 153288 bytes, checksum: 0a1e1c45794cf17f3eaedd95db054ac6 (MD5) Previous issue date: 2011-11-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T13:23:14Z No. of bitstreams: 1 WOS000295663600026.pdf: 153288 bytes, checksum: 0a1e1c45794cf17f3eaedd95db054ac6 (MD5) Made available in DSpace on 2014-05-20T13:23:14Z (GMT). No. of bitstreams: 1 WOS000295663600026.pdf: 153288 bytes, checksum: 0a1e1c45794cf17f3eaedd95db054ac6 (MD5) Previous issue date: 2011-11-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Nasal mucociliary system is the first line of defense of the upper airways and may be affected acutely by exposure to particulate matter (PM) from biomass burning. Several epidemiologic studies have demonstrated a consistent association between levels of air pollution from biomass burning with increases in hospitalization for respiratory diseases and mortality. To determine the acute effects of exposure to particulate matter from biomass burning in nasal mucociliary transport by saccharin transit time (STT) test, we studied thirty-three non-smokers and twelve light smokers sugarcane cutters in two periods: pre-harvest season and 4 h after harvest at the first day after biomass burning. Lung function, exhaled carbon monoxide (CO), nasal symptoms questionnaire and mucociliary clearance (MC) were assessed. Exhaled CO was increased in smokers compared to non-smokers but did not change significantly after harvest. In contrast, SIT was similar between smokers and non-smokers and decreased significantly after harvest in both groups (p < 0.001). Exposure to PM from biomass burning did not influence nasal symptoms. Our results suggest that acute exposure to particulate matter from sugarcane burned affects mucociliary clearance in smokers and non-smokers workers in the absence of symptoms. (C) 2011 Elsevier Ltd. All rights reserved. State Univ São Paulo, Dept Physiotherapy, BR-19060900 São Paulo, Brazil State Univ São Paulo, Dept Phys Chem & Biol, BR-19060900 São Paulo, Brazil State Univ São Paulo, Dept Physiotherapy, BR-19060900 São Paulo, Brazil State Univ São Paulo, Dept Phys Chem & Biol, BR-19060900 São Paulo, Brazil