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Dive into the research topics where Sônia Maria Carvalho Neiva Tanaka is active.

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Featured researches published by Sônia Maria Carvalho Neiva Tanaka.


Talanta | 2006

Amperometric sensor for nitrite using a glassy carbon electrode modified with alternating layers of iron(III) tetra-(N-methyl-4-pyridyl)-porphyrin and cobalt(II) tetrasulfonated phthalocyanine.

Wilney de Jesus Rodrigues Santos; Aline L. Sousa; Rita de Cássia Silva Luz; Flavio Santos Damos; Lauro T. Kubota; Auro Atsushi Tanaka; Sônia Maria Carvalho Neiva Tanaka

The development of a highly sensitive amperometric sensor for nitrite using a glassy carbon electrode modified with alternated layers of iron(III) tetra-(N-methyl-4-pyridyl)-porphyrin (FeT4MPyP) and cobalt(II) tetrasulfonated phthalocyanine (CoTSPc) is described. The modified electrode showed an excellent catalytic activity and stability for the nitrite oxidation decreasing the peak potentials about 200mV toward less positive values and presenting much higher peak currents than those obtained on the bare GC electrode. A linear response range of 0.2-8.6mumoll(-1), with a sensitivity of 0.37muAlmumol(-1) and detection limit of 0.04mumoll(-1) were obtained with this sensor. The repeatability of the proposed sensor, evaluated in term of relative standard deviation, was verified to be 1.4% for 10 measurements of 0.2mumoll(-1) nitrite solution. Interference caused by common ions has been investigated in simulated mixtures containing high concentration level of interfering ions and the sensor was found to be tolerant against these ions. The developed sensor was applied for the nitrite determination in water samples and the results were in agreement with those obtained by a comparative method described in the literature. The average recovery for these samples was 100.1 (+/-0.7)%.


Talanta | 2008

Amperometric sensor for nitrite based on copper tetrasulphonated phthalocyanine immobilized with poly-L-lysine film.

Aline L. Sousa; Wilney de Jesus Rodrigues Santos; Rita de Cássia Silva Luz; Flavio Santos Damos; Lauro T. Kubota; Auro Atsushi Tanaka; Sônia Maria Carvalho Neiva Tanaka

In this work, an amperometric sensor for nitrite detection based on a glassy carbon electrode modified with copper tetrasulphonated phthalocyanine immobilized by polycationic poly-L-lysine film is presented. The modified electrode showed an excellent catalytic activity toward nitrite oxidation. A linear response range from 0.12 up to 12.20 micromol L(-1) was obtained with a sensitivity of 0.83 microA L micromol(-1). The detection limit for nitrite was 36 nmol L(-1). The repeatability of the proposed sensor, evaluated in terms of relative standard deviation, was 1% for 10 measurements of 10 micromol L(-1) nitrite solution. Finally, the developed sensor was applied for nitrite determination in water samples and the results were in agreement to the comparative method. The average recovery for the samples was 101 (+/-4)%.


Analyst | 2003

Iron(III) tetra-(N-methyl-4-pyridyl)-porphyrin as a biomimetic catalyst of horseradish peroxidase on the electrode surface: An amperometric sensor for phenolic compound determinations

Flavio Santos Damos; Maria Del Pilar Taboada Sotomayor; Lauro T. Kubota; Sônia Maria Carvalho Neiva Tanaka; Auro Atsushi Tanaka

The use of iron(III) tetra-(N-methyl-4-pyridyl) porphyrin (FeIIIT4MpyP) and histidine (His) in the construction of an amperometric sensor for phenolic compound determinations is reported, based on horseradish peroxidase (HRP) chemistry. The sensor was prepared by modifying a glassy carbon electrode with Nafion membrane doped with FeIIIT4MpyP and His, in a mass ratio of 1:2. The sensor presented its best performance at 50 mV vs. SCE in 0.1 mol l(-1) succinate buffer (pH = 4.0) containing 125 micromol l(-1) H2O2. Under optimized operational conditions, a linear response range from 0.6 to 6.0 micromol l(-1) was obtained with a sensitivity of 61 nA cm(-2) micromol l(-1). The detection limit for catechol determination was 0.35 micromol l(-1). The response time was less than 0.5 s. The proposed sensor presented stable responses for 100 successive determinations, while satisfactory responses were observed even after 200 measurements. The repeatability, evaluated in terms of relative standard deviation, was 4% for n = 7. The signal responses for other phenolic compounds, including those of environmental and clinical interest, were also investigated.


Journal of the Brazilian Chemical Society | 2008

Electrocatalytic oxidation of hydrazine in alkaline media promoted by iron tetrapyridinoporphyrazine adsorbed on graphite surface

Luiza M F Dantas; Alaécio P. Dos Reis; Sônia Maria Carvalho Neiva Tanaka; José H. Zagal; Yo Ying Chen; Auro Atsushi Tanaka

The electrocatalytic oxidation of hydrazine was studied using an ordinary pyrolytic graphite electrode modified with iron tetrapyridinoporphyrazine complex (FeTPyPz), employing cyclic voltammetry and rotating disk electrode techniques. Analyses of the voltammograms recorded at different potential scan rates and the polarization curves at different electrode rotation rates showed that the reaction of electrooxidation of hydrazine on FeTPyPz occurs via 4-electrons with the formation of N2 as main product. The kinetic parameters suggest that the second electron transfer step is rate controlling. The activity of FeTPyPz depends on its Fe(II)/Fe(I) formal potential and fits well in a volcano plot that includes several iron phthalocyanines, indicating that such formal potential is a good reactivity index for these complexes.


Journal of the Brazilian Chemical Society | 2009

Manganese phthalocyanine as a biomimetic electrocatalyst for phenols in the development of an amperometric sensor

Wilney de Jesus Rodrigues Santos; Aline L. Sousa; Maria Del Pilar Taboada Sotomayor; Flavio Santos Damos; Sônia Maria Carvalho Neiva Tanaka; Lauro T. Kubota; Auro Atsushi Tanaka

The construction of an amperometric sensor for phenolic compounds using a carbon paste electrode modified with manganese phthalocyanine and histidine is reported. Under optimized conditions, at 0 mV vs Ag/AgCl in 0.1 mol dm-3 phosphate buffer solutions (pH 7.0) containing 250 µmol dm-3 H2O2, a linear response for catechol from 20 up to 130 µmol dm-3 was obtained with a sensitivity of 0.56 (± 0.02) µA dm3 µmol-1 cm-2. The detection limit was 1.1 µmol dm-3 and the response time was 2 s. The sensor presented stable response during 40 successive determinations. The repeatability, evaluated in terms of relative standard deviation, was 3.6% for n = 5 and [catechol] = 10 µmol dm-3. The sensor responses for other phenolic compounds were also investigated in details. Finally, the applicability of the sensor was tested in a pharmaceutical containing dopamine and the results compared favorably with those obtained with the official method.


Analyst | 2008

Electrochemical sensor highly selective for estradiol valerate determination based on a modified carbon paste with iron tetrapyridinoporphyrazine

Isabelle V. Batista; Marcos R. V. Lanza; Iara Lúcia Tescarollo Dias; Sônia Maria Carvalho Neiva Tanaka; Auro Atsushi Tanaka; Maria Del Pilar Taboada Sotomayor

This work reports the use of iron tetrapyridinoporphyrazine (FeTPyPz) as a highly selective catalyst in the construction of an electrochemical sensor for estradiol valerate (EV) determination. The sensor was prepared by modifying a carbon paste with FeTPyPz. The best results were obtained in a mixture of acetonitrile (MeCN) and 0.1 mol L(-1) phosphate buffer solution (pH 6.0) in a volume ratio of 47 : 53. A linear response range was observed between 45 and 450 micromol L(-1) with a sensitivity of 12160 +/- 306 microA L mol(-1) and quantification and detection limits of 45 and 13 micromol L(-1), respectively. The repeatability, expressed as the relative standard deviation (RSD) for n = 10, was 5.9% ([EV] = 50 micromol L(-1)). The reproducibility (RSD) for the sensor construction was better than 4% and the operational stability (RSD) over 50 measurements was 1.8%. A detailed investigation regarding the selectivity and electrochemical characteristics was carried out. Finally, in a first step to evaluate the application potential of the sensor, it was successfully applied to determine EV in a commercial formulation.


Talanta | 2011

Quantification of N-acetylcysteine in pharmaceuticals using cobalt phthalocyanine modified graphite electrodes

Iranaldo Santos da Silva; Marcelo Fernando Antão Araújo; Henrique Augusto Ferreira; Jaldyr de Jesus Gomes Varela; Sônia Maria Carvalho Neiva Tanaka; Auro Atsushi Tanaka; Lúcio Angnes

Flow injection analysis (FIA) with amperometric detection was employed for the quantification of N-acetylcysteine (NAC) in pharmaceutical formulations, utilizing an ordinary pyrolytic graphite (OPG) electrode modified with cobalt phthalocyanine (CoPc). Cyclic voltammetry was used in preliminary studies to establish the best conditions for NAC analysis. In FIA-amperometric experiments the OPG-CoPc electrode exhibited sharp and reproducible current peaks over a wide linear working range (5.0×10(-5)-1.0×10(-3) mol L(-1)) in 0.1 mol L(-1) NaOH solution. High sensitivity (130 mA mol(-1) cm(2)) and a low detection limit (9.0×10(-7) mol L(-1)) were achieved using the sensor. The repeatability (R.S.D.%) for 13 successive flow injections of a solution containing 5.0×10(-4) mol L(-1) NAC was 1.1%. The new procedure was applied in analyses of commercial pharmaceutical products and the results were in excellent agreement with those obtained using the official titrimetric method. The proposed amperometric method is highly suitable for quality control analyses of NAC in pharmaceuticals since it is rapid, precise and requires much less work than the recommended titrimetric method.


Journal of the Brazilian Chemical Society | 2010

Application of a biomimetic sensor based on iron phthalocyanine chloride: 4-methylbenzylidene-camphor detection

Ana Carolina Boni; Maria Del Pilar Taboada Sotomayor; Marcos R.V. Lanza; Sônia Maria Carvalho Neiva Tanaka; Auro Atsushi Tanaka

The construction and application of a biomimetic sensor for determination of 4-methylbenzylidene camphor (4-MBC), an ultraviolet (UV) radiation protector, are described. The sensor was prepared by modifying a carbon paste electrode with iron(III) phthalocyanine chloride (FePcCl). Amperometric measurements carried out with the sensor under an applied potential of 0.0 V vs. Ag|AgCl in a mixture of tetrahydrofuran and 0.1 mol L-1 H2SO4 solution (30:70 volume ratio) showed a linear response range from 1.8×10-4 to 9.0×10-4 mol L-1. A detailed selectivity investigation for other nine UV filters was also performed. A sensor response mechanism was proposed and the results for 4-MBC quantification in commercial sunscreens and in water from swimming pools and rivers are presented.


Food Chemistry | 2009

Determination of nitrite in food samples by anodic voltammetry using a modified electrode

Wilney de Jesus Rodrigues Santos; Phabyanno Rodrigues Lima; Auro Atsushi Tanaka; Sônia Maria Carvalho Neiva Tanaka; Lauro T. Kubota


Sensors and Actuators B-chemical | 2011

A hemin-based molecularly imprinted polymer (MIP) grafted onto a glassy carbon electrode as a selective sensor for 4-aminophenol amperometric

José de Ribamar Martins Neto; Wilney de Jesus Rodrigues Santos; Phabyanno Rodrigues Lima; Sônia Maria Carvalho Neiva Tanaka; Auro Atsushi Tanaka; Lauro T. Kubota

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Auro Atsushi Tanaka

Federal University of Maranhão

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Lauro T. Kubota

State University of Campinas

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Flavio Santos Damos

Federal University of Maranhão

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Aline L. Sousa

Federal University of Maranhão

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Ana Paula Mota Ferreira

Federal University of Maranhão

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Glaucia Tinoco Corrêa

Federal University of Maranhão

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