Implementação de tecnicas de luminescencia em quimica analitica

AUTOR(ES)
DATA DE PUBLICAÇÃO

1991

RESUMO

This work involves two parts. The first one is related to the development of the Room-Temperature Phosphorescence as an analytical technique. In this case, the sample to be analysed is adsorbed on the surface of a solid material (filter paper or silica-gel) or dissolved in a micellar medium. In the beginning a nitrogen laser spectrofluorimeter was used for sample analysis. However, this showed to be inadequate because: 1) the only wavelegth available from the laser is 337,1 nm and 2) there is an intense substrate emission due to strong radiation. The treatments carried out (extractions with several solvents and photodegradation with UV-radiation from a Hg lamp) on these papers to reduce this emission were unsuccessful. Silica-gel, shows less intense emission but does not have enough adherence to the glass surface while micellar solutions demands vigorous oxygen remotion. Therefore, from an analytical viewpoint, both are impracticable. The second part of this work consisted in the use of fluorimety to get the spectra and analytical curves for some pharmaceutical drugs in micellar media. These were: levomepromazine maleate (I), chlorpromazine hydrochloride (II), acridine orange (III), merbromin (IV) and crystal violet (V) and the followings surfactants: SDS, CTAB and Brij-35. The spectra were obtained through a conventional spectrofluorimeter.The lowest concentrations determined for compounds I and II were about 10and 10 M, respectively. For these solutions, we could see the effect of aggregates formation on the spectra. Compound III was determined until concentrations c.a. 10M; further on, we investigated the ionic-pair and pre-micellar aggregate formation on the spectra for concentrations below c.m.c.. For IV, it was studied the influence of pH on the absorption and emission spectra from which it was concluded that exists different acid-base equilibrium species. The smallest concentrations obtained for IV was 10M for the Brij-35 solution in buffered medium (pH 11,5). Finally V did not show the same behavior in the pH range of 3 to 7. The lower limit concentration was 10M and Brij-35 was the one responsible for that highest emission signals.

ASSUNTO(S)

luminescencia quimica analitica

ACESSO AO ARTIGO

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