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Determina??o simult?nea de catecol e hidroquinona empregando um sensor seletivo ? base de ftalocianina de mangan?s e nanotubos de carbonoSilva, Saimon Moraes 12 July 2012 (has links)
?rea de concentra??o: Qu?mica Anal?tica / Submitted by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2014-12-10T11:52:19Z
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PPGQ - Mestrado em Qu?mica (Disserta??es) (ID: 150)
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Dissertacao_Saimon_Final.pdf.txt: 148365 bytes, checksum: 0a99c3be8d2cda4ce737a53a561cf7a5 (MD5) / O presente trabalho descreve o desenvolvimento de um sensor voltam?trico seletivo e sens?vel para a determina??o simult?nea de catecol (CC) e hidroquinona (HQ) usando um eletrodo de carbono v?treo (ECV) modificado com ftalocianina de mangan?s (MnPc) adsorvida sobre nanotubos de carbono de paredes m?ltiplas (NTCPM). O eletrodo modificado apresentou uma excelente atividade eletroqu?mica tanto para oxida??o quanto para a redu??o de CC e HQ. No ECV/NTCPM/MnPc tanto CC, quanto HQ podem gerar um par redox quase-revers?vel e picos bem definidos. Sob as condi??es experimentais e operacionais otimizadas, a corrente de pico cat?dica foi linear na faixa de 1,0 x 10-6 mol L-1 a 6,0 x 10-4 mol L-1 para ambos, CC e HQ, com limites de detec??o de 0,95 e 0,41 ?mol L-1, respectivamente. Adicionalmente, as correntes de pico an?dicas foram linear na faixa de 1,0 x 10-6 mol L-1 a 6,0 x 10-4 mol L-1 para ambos, CC e HQ, com limites de detec??o de 0,96 e 0,48 ?mol L-1, respectivamente. O m?todo proposto foi eficazmente aplicado na detec??o simult?nea de hidroquinona e catecol em amostras de ?gua. / Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Qu?mica, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2012. / ABSTRACT
The present work describes the development of a selective and sensitive voltammetric sensor for catechol (CC) and hydroquinone (HQ) using a glassy carbon (GC) electrode modified with manganese phthalocyanine (MnPc) adsorbed on multiwalled carbon nanotubes (MWCNT). The modified electrode showed an excellent electrochemical activity towards the oxidations and reductions of CC and HQ. At the GC/MWCNT/MnPc electrode both CC and HQ can generate a pair of quasi-reversible and well-defined redox peaks. Under the optimized experimental and operational conditions, the cathodic peak current was linear over the 1.0 x 10-6 mol L-1 to 6.0 x 10-4 mol L-1 range for both CC and HQ, with detection limits of 0.95 and 0.41 ?mol L-1, respectively. In addition, anodic peak current were linear over the 1.0 x 10-6 mol L-1 range to 6.0 x 10-4 mol L-1 for both CC and HQ, with detection limits of 0.96 and 0.48 ?mol L-1, respectively. The proposed method was effectively applied to the simultaneous detection of hydroquinone and catechol in water samples.
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Determina??o voltam?trica de estriol em formula??o farmac?utica e urina utilizando um eletrodo de carbono v?treo modificado com um filme de poli(metionina) e cobaltoGomes, Eliziana Santana 28 July 2017 (has links)
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Previous issue date: 2017 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / O estriol (C18H24O3, denominado E3) ? o principal esteroide estrog?nico produzido na
gravidez. O uso do estriol ? comum para o tratamento da menopausa como alternativa ao 17?-
estradiol, estrona ou a uma combina??o destes dois f?rmacos. O principal objetivo deste
trabalho foi estudar o perfil voltam?trico do estriol utilizando a voltametria c?clica e
desenvolver uma metodologia para a sua determina??o em comprimidos e urina utilizando a
voltametria de pulso diferencial (DPV) e o eletrodo de carbono v?treo modificado com um
filme de polimetionina e cobalto. Os resultados mostraram que em solu??o de tamp?o fosfato
a 0,1 mol L-1 (pH 7,0) o E3 oxidou irreversivelmente no potencial de +0,58V, apresentando
uma boa defini??o do pico. A curva anal?tica para o E3 foi linear no intervalo de concentra??o
de 0,60 ?mol L-1 ? 4,76 ?mol L-1 (R2 = 0,996) e 5,66 ?mol L-1 ? 9,90 ?mol L-1 (R2 = 0,994),
com limites de detec??o e de quantifica??o iguais a 3,40x10-8 mol L-1 e 1,13 x 10-7 mol L-1,
respectivamente. A precis?o foi avaliada atrav?s de an?lises voltam?tricas do estriol
realizadas em um mesmo dia e em dias diferentes e apresentaram desvios padr?es relativos
(RSD) inferiores a 5,0%, mostrando que o m?todo desenvolvido ? preciso. Os estudos sobre
interferentes mostraram que as subst?ncias presentes nas amostras de comprimido (lactose,
estearato de magn?sio e amido) ou urina (?cido ?rico, ?cido asc?rbico e ?cido c?trico) n?o
interferiram de maneira significativa na determina??o do E3. Al?m disso, o m?todo
desenvolvido foi comparado estatisticamente com um m?todo citado na farmacop?ia atrav?s
do teste-t e do teste-F. Os resultados mostraram que os valores de t e F calculados foram
menores do que os valores de t e F cr?ticos, indicando que n?o houve diferen?a estat?stica
significativa entre os m?todos. A exatid?o do m?todo foi avaliada tamb?m por estudos de
adi??o e recupera??o. As recupera??es do E3 variaram de 97,7 ? 100,9% para a formula??o
farmac?utica e 99,0 ? 100,9% para a urina, indicando que n?o houve efeitos de interfer?ncia
de matriz significativos e que o m?todo apresenta boa exatid?o. Desta forma, a valida??o da
metodologia desenvolvida demonstrou que o m?todo proposto pode ser aplicado com sucesso
na determina??o do E3 em medicamentos e urina humana. / Disserta??o (Mestrado) ? Programa de P?s-gradua??o em Ci?ncias Farmac?uticas, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2017. / The estriol (C18H24O3, named as E3) is the main estrogenic steroid produced during
pregnancy. The E3 is used to treatment of menopause as an alternative for 17?-estradiol,
estrone or a combination of both. The main goal of this work was to study the voltammetric
profile of E3 using cyclic voltammetry in order to develop a methodology for its
determination in tablets and urine using differential pulse voltammetry (DPV) and the glass
carbon electrode modified with a film of polymethionine and cobalt. The results showed that
the E3 was oxidized at + 0.58V in a 0.1 molL-1 phosphate buffer solution (pH 7.0), giving a
good peak definition. The analytical curve for E3 was linear in the concentration range of 0.60
?molL-1 ? 4.76 ?molL-1 (R2 = 0.996) and 5.66 ?molL-1 ? 9.90 ?molL- 1 (R2 = 0.994 with lmits
of detection and quantification of 3.40x10-8 molL-1 and 1.13x10-7 molL-1, respectively. The
precision was evaluated by recording voltammograms of E3 on the same or different day. The
relative standard deviations were lower than 5.0% for each test, indicating that the developed
method has good precision. The interfering study showed that the tested substances do not
interfered significantly in the determination of E3, as for both tablets (lactose, magnesium
stearate and starch) or urine test (uric acid, ascorbic acid and citric acid). Furthermore, the
developed method was compared to the suggested method from American Pharmacopoeia
using the t-test and the F-test. The results showed that the calculated values of t and F were
lower than their critical values, indicating no significant statistical difference between the
methods. The accuracy of the method was also evaluated by studies of addition and recovery.
The recovery of E3 ranged from 97.7 ? 100.9% for the pharmaceutical formulation and 99.0 ?
100.9% for the urine, indicating no significant effects of matrix interference and that the
developed method presented accuracy. Thus, the validation of the developed methodology
demonstrated that the proposed method can be applied successfully to the determination of E3
in drugs and human urine.
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Desenvolvimento e valida??o de metodologias eletroanal?ticas para determina??o de f?rmacos antituberculoseFerraz, Bruno Regis Lyrio 11 March 2016 (has links)
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Previous issue date: 2016 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Funda??o de Amparo a Pesquisa do Estado de Minas Gerais (FAPEMIG) / RESUMO
Etionamida e pirazinamida s?o antibi?ticos ?teis no tratamento da tuberculose
multirresistente. O presente trabalho descreve o desenvolvimento e valida??o de metodologias
eletroanal?ticas para determina??o de etionamida e pirazinamida em formula??es
farmac?uticas e em urina humana empregando um eletrodo de diamante dopado com boro e
um eletrodo de carbono v?treo modificado comum filme de poli glicina. Durante o
desenvolvimento de ambas as metodologias, a voltametria c?clica foi empregada para verificar
a influ?ncia do pH, da velocidade de varredura e do eletr?lito suporte no comportamento
eletroqu?mico de ambos os analitos, bem como foram calculados os n?meros de pr?tons e
el?trons envolvidos em cada uma das rea??es eletroqu?micas. A voltametria de onda quadrada
com os par?metros otimizados foi utilizada para construir curvas anal?ticas para a ETO e
PZA. Para a ETO foi obtido um intervalo linear de 1,0 a 80,0 ?mol L?1, com LOD e LOQ
iguais a 0,294 e 0,980 ?mol L?1, respectivamente. Para a PZA foi obtido um intervalo linear
de 0,47 a 6,16 ?mol L?1, com LOD e LOQ iguais a 0,035 e 0,12 ?mol L?1, respectivamente. A
precis?o foi avaliada pelo registro de voltamogramas no mesmo dia e em dias diferentes,
obtendo-se desvios padr?es relativos, inferiores a 5,0% em ambos os m?todos. Os resultados
dos estudos de interferentes mostraram que nenhuma das subst?ncias testadas interferiu de
maneira significativa na determina??o de ambos os f?rmacos. Os m?todos desenvolvidos
foram comparados estatisticamente com os protocolos oficiais da farmacopeia atrav?s do
teste-t e do teste-F, e os resultados mostraram que os valores de t e F calculados foram
menores do que os valores de t e F cr?ticos, indicando que n?o houve diferen?a estat?stica
entre as m?dias. A exatid?o de ambos os m?todos foi avaliada tamb?m por estudos de adi??o
e recupera??o, obtendo-se como resultados percentuais de recupera??o pr?ximos a 100% para
ambos os m?todos. A valida??o das metodologias desenvolvidas foi realizada pela avalia??o
dos par?metros anal?ticos como sensibilidade, seletividade, limite de detec??o, limite de
quantifica??o, faixa linear, exatid?o e precis?o e os resultados obtidos foram satisfat?rios.
Portanto, os m?todos desenvolvidos podem ser aplicados com sucesso na determina??o dos
f?rmacos ETO e PZA em medicamentos e urina humana. / Disserta??o (Mestrado) ? Programa de P?s-gradua??o em Ci?ncias Farmac?uticas, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2016. / ABSTRACT
Ethionamide and pyrazinamide antibiotics are useful in the treatment of multidrugresistant
tuberculosis. This work describes the development and validation of electroanalytical
methodologies for determination of ethionamide and pyrazinamide in pharmaceutical
formulation and human urine using boron-doped diamond electrode and poly glycine
modified glassy carbon electrode, respectively. During the development of both
methodologies, cyclic voltammetry was used to investigate the influence of pH, scan rate and
the supporting electrolyte on the electrochemical behavior of both analytes, as well as the
numbers of protons and electrons involved in each of the electrochemical reactions were
calculated. Square wave voltammetry with optimized parameters were used to construct
standard curves for ETO and PZA. For ETO a linear range from 1.0 to 80.0 ?mol L?1 was
obtained with LOD and LOQ equal to 0.294 and 0.980 ?mol L?1, respectively. For PZA a
linear range from 0.47 to 6.16 ?mol L?1was obtained with LOD and LOQ equal to 0.035 and
0.12 ?mol L?1, respectively. The precision was evaluated by voltammograms record on the
same day and on different days, obtaining relative standard deviation less than 5.0% in both
methods. The results of interfering studies showed that none of the tested substance interferes
significantly in the determination of both drugs. The developed methods were statistically
compared with the pharmacopoeia official protocols through the t-test and F-test, and the
results showed that the calculated t and F values were lower than the critical t and F values
indicating that there was no statistical difference between the averages. The accuracy of both
methods was also evaluated by addition and recovery studies, obtaining results as percentage
recovery close to 100% for both methods. The validation of the developed methodologies was
carried out by the evaluation of analytical parameters such as sensitivity, selectivity, detection
limit, quantification limit, linear range, accuracy and precision and the obtained results were
satisfactory. Therefore, the developed methods can be applied successfully in the
determination of ETO and PZA drugs in pharmaceuticals and human urine.
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