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Título: DEVELOPMENT AND COMPARISON OF VOLTAMMETRIC METHODS FOR THE DETERMINATION OF CYCLOFENIL AND PRIMAQUINE IN PHARMACEUTICAL FORMULATIONS AND IN URINE
Autor: WAGNER FELIPPE PACHECO
Instituição: PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO - PUC-RIO
Colaborador(es):  RICARDO QUEIROZ AUCELIO - ADVISOR
Nº do Conteudo: 5180
Catalogação:  13/07/2004 Idioma(s):  PORTUGUESE - BRAZIL
Tipo:  TEXT Subtipo:  THESIS
Natureza:  SCHOLARLY PUBLICATION
Nota:  Todos os dados constantes dos documentos são de inteira responsabilidade de seus autores. Os dados utilizados nas descrições dos documentos estão em conformidade com os sistemas da administração da PUC-Rio.
Referência [pt]:  https://www.maxwell.vrac.puc-rio.br/colecao.php?strSecao=resultado&nrSeq=5180@1
Referência [en]:  https://www.maxwell.vrac.puc-rio.br/colecao.php?strSecao=resultado&nrSeq=5180@2
Referência DOI:  https://doi.org/10.17771/PUCRio.acad.5180

Resumo:
In this work, square-wave and differential pulse voltammetric methods were developed for the determination of cyclofenil and primaquine in pharmaceutical formulations and in urine samples. The use of the square- wave acquisition technique was found to enable better sensitivity and faster analysis time compared to the differential pulse technique. Experimental and instrumental conditions were optimized to allow the best analytical performance in terms of limit of detection and repeatability of the readings. In the case of cyclofenil, its unstable behavior in aqueous and organic solvents, with systematic decreasing of analyte current signal, makes impossible any voltammetric determination. As an alternative way, the electrochemical properties of a stable photochemical derivative of cyclofenil was used (the compound was irradiated with UV radiation for 45 min) with maximum current at -1,28 V. This analyte photoderivative could also be accumulated in the working electrode. The experimental conditions that allowed the maximum current was a 30 s of deposition time at the mercury electrode, Britton- Robbinson (pH 9,0) supporting electrolyte, accumulation potential of -0,9 V, amplitude of pulse of 250 mV, scan increment 2,0 mV. These optimized conditions allowed a limit of detection of 10-8 mol L-1 and dynamic linear range of 2 orders of magnitude to be achieved. These analytical figures of merit made possible the determination of cyclofenil either in a pharmaceutical formulation (Menopax) and in urine samples spiked with the analyte of interest. The potential interferences from concomitant substances used in the pharmaceutical formulation were also evaluated. For the analyte determination in urine, only UV irradiation of sample was necessary, in order to obtain stable cyclofenil derivative. The analyte addition method was used to analyze urine in order to minimize matrix interferences. Recovery results for the analysis of Menopax and for the analysis of urine were between 96,5 and 107,6 percent, within the acceptable recovery range established by the United States Pharmacopoeia. Information concerning the analyte redox reaction and electrode processes was also obtained from differential pulse voltammetry, square-wave voltammetry and cyclic voltammetry. It was verified that the cyclofenil photoderivative eletrochemical reaction is reversible with adsorption of only the reagent on the surface of the electrode. The adsorption of the electrochemical reduction product does not occur. It was also verified that the process involves the transference of only one electron, and there is no kinetics contribution in the reaction. In the case of the primaquine the analyte reduction occurs in anodic region (0,592 V), therefore, it was necessary the use the carbon glass electrode to allow the determination of this analyte. The pre-concentration of the analyte in the working carbon glass electrode was also not attained with the experimental conditions used. Several attempts were made to make possible the use of the mercury electrode, including the formation of charge transfer complexes with iodine and complexation with vanadium. However no success was obtained. Using the carbon glassy electrode and DPV technique the determination of primaquine in pharmaceutical formulations and urine was performed with average recovery of 101.7 percent. Limit of detention of 1,0 x 10-6 mol L- 1 was obtained.

Descrição Arquivo
COVER, ACKNOWLEDGEMENTS, RESUMO, ABSTRACT, SUMMARY AND LISTS  PDF
CHAPTER 1  PDF
CHAPTER 2  PDF
CHAPTER 3  PDF
CHAPTER 4  PDF
CHAPTER 5  PDF
CHAPTER 6  PDF
REFERENCES  PDF
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