Propriedades analíticas de materiais a base de sílica e óxido de titânio modificados

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Catalisadores 'PT' e 'PTSN' modificados com 'SN''O IND.2' para a oxidação eletroquímica de etanol

Pós-graduação em Química - IQ

Determination of tetradifon in brazilian green bell pepper by differential pulse voltammetry

Tetradifon, a potentially carcinogenic and mutagenic pesticide, can contribute to environmental and human contamination when applied to green bell pepper crops. In this context, in this work, a reliable and sensitive method for determination of tetradifon in Brazilian green bell pepper samples involving a differential pulse voltammetry (DPV) technique on a glassy carbon electrode is proposed. The electrochemical behavior of tetradifon as followed by cyclic voltammetry (CV) suggests that its reduction occurs via an irreversible five–electron transfer vs. Ag|AgCl, KCl 3 M reference electrode. Very well–resolved diffusion controlled voltammetric peaks have been obtained in a supporting electrolyte solution composed of a mixture of 40% dimethylformamide (DMF), 30% methanol, and 30% NaOH 0.3 mol L−1 at −1.43, −1.57, −1.73, −1.88, and −2.05 V. The proposed DPV method has a good linear response in the 3.00 – 10.0 μmol L−1 range, with a limit of detection (L.O.D) of 0.756 μmol L−1 and 0.831 μmol L−1 in the absence and in the presence of the matrix, respectively. Moreover, improved L.O.D results (0.607 μmol L−1) have been achieved in the absence of DMF from the supporting electrolyte solution. Recovery has been evaluated in five commercial green bell pepper samples, and recovery percentages ranging from 91.0 to 109 have been obtained for tetradifon determinations. The proposed voltammetric method has also been tested for reproducibility, repeatability, and potential interferents, and the results obtained for these three analytical parameters are satisfactory for electroanalytical purposes.

New voltammetry-based technique for the determination of tebuthiuron in crystal and brown sugar samples

Sugar is widely consumed worldwide and Brazil is the largest producer, consumer, and exporter of this product. To guarantee proper development and productivity of sugar cane crops, it is necessary to apply large quantities of agrochemicals, especially herbicides and pesticides. The herbicide tebuthiuron (TBH) prevents pre- and post-emergence of infesting weed in sugarcane cultures. Considering that it is important to ensure food safety for the population, this paper proposes a reliable method to analyse TBH in sugar matrixes (brown and crystal) using square wave voltammetry (SWV) and differential pulse voltammetry (DPV) at bare glassy carbon electrode and investigate the electrochemical behavior of this herbicide by cyclic voltammetry (CV). Our results suggest that TBH or the product of its reaction with a supporting electrolyte is oxidized through irreversible transfer of one electron between the analyte and the working electrode, at a potential close to +1.16 V vs. Ag |AgClsat in 0.10 mol L-1 KOH as supporting electrolyte solution. Both DPV and SWV are satisfactory for the quantitative analysis of the analyte. DPV is more sensitive and selective, with detection limits of 0.902, 0.815 and 0.578 mg kg-1, and quantification limits of 0.009, 0.010 and 0.008 mg kg-1 in the absence of the matrix and in the presence of crystal and brown sugar matrix, respectively. Repeatability lay between 0.53 and 13.8%, precision ranged between 4.14 and 15.0%, and recovery remained between 84.2 and 113% in the case of DPV conducted in the absence of matrix and in the presence of the crystal sugar matrix, respectively.

Estudo das reações de oxidação de metanol e etanol sobre catalisadores bimetálicos suportados preparados por métodos coloidais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Preparação, caracterização e aplicação de carbono polimérico vítreo em sensores eletroquímicos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Aplicação do '[RuCl IND. 3(DPPB)H IND.2 O] na obtenção do complexos mono e binucleares

Pós-graduação em Química - IQ

Compostos derivados de benzilcobaloximas: estudo por espectrometria de massas, análise térmica e eletroquímica

Pós-graduação em Química - IQ

Preparação e caracterização eletroquímica de material catódico do tipo La2/3-xLi3xTiO3 para aplicações em baterias de Lítio

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Polymer brush modified electrode with switchable selectivity triggered by pH changes enhanced by gold nanoparticles

In this work, a sensor was built up with smart material based on polymer brush and gold nanoparticles. The modified electrode functionalized with polyacrylic acid (PAA) tethered to indium tin oxide (ITO) and covered with gold nanoparticle (ITO/PAA/Au) demonstrated switchable interfacial properties discriminating different pHs. The switchable electrochemical and plasmonic process was characterized by cyclic voltammetry (CV), electrochemistry impedance spectroscopy (EIS), and localized surface plasmon resonance (LSPR).

Electrochemical studies based on local interfacial ph changes of gold nanoparticles immobilized on polystyrene brushes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Electrodeposition of Ni-B and Ni-Co-B Alloys by Using Boric Acid as Boron Source

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Cobalt(III) complexes with thiosemicarbazones as potential anti-Mycobacterium tuberculosis agents

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Investigação da condução elétrica em fitas duplas de dna imobilizadas em eletrodos de ouro por medidas eletroquímicas

Pós-graduação em Química - IQ

Estudo eletroquímico do sistema microestruturado montmorilonita-8- hidroxiquinolina na presença de íons metálicos

Pós-graduação em Química - IBILCE