Estudo fisico-quimico do transporte de especies quimicas atraves de membranas liquidas hidrofobicas em tempo real

AUTOR(ES)
DATA DE PUBLICAÇÃO

2000

RESUMO

Transport processes of variated chemical species - potassium ions, amino acids and vitamins - through hidrophobic liquid membranes was studied using BLM (bulk liquid membrane) method. UV - Vis spectroscopy was used in all cases to quantify the tranported species. It was not possible to use univariate calibration in cases of simultaneous transport because their spectral overlap. Chemometric methods as OLS (ordinary least squares), PLS (partial least squares) and TLD (trilinear decomposition) were employed. In addition, two levels factorial design was performed. For the K ion was used as carrier the crown ether 18C6, in series of experiments with membranes of CH2Cl2, CHCl3 and CCl4, as function of temperature and initial concentration of compounds to be transported. Salicylate, benzoate, several kinds of nitrophenolates and homologous series of bactericides (parabens and acoxyphenols) were employed as contra-ions. In general, results could be explained by using the Born equation. Some calorimetric experiments were done to relate biological response with transport rates. Amino acids as Phenylalanine, Triptophane and Tyrosine were used to perform the transport by reversed micelles of AOT (an anionic surfactant) in CH2Cl2 and CHCl3, and two other reversed micelles of TOMAC and DODAC (cationic surfactants) in CHCl3. According to the nature of the used surfactant, pH was changed in receiving and source phases. Transport process was efficient only in cases where AOT was employed. Ascorbic acid transport was studied by using CH2Cl2 and CHCl3 membranes containing phenylboronic acid as carrier. Parameters like carrier concentration influence, vitamin initial concentration, temperature, glutathione effect in the receiving phase and solvent effect were used to investigate the transfer rates through liquid membranes. Simultaneous transport of ascorbic acid and riboflavin was studied using the same solvents and changing carrier concentration from zero to 8.10 mol.L. In all cases, an increasing of transport rates was observed only until carrier concentration of 4.10 mol.L. Competition between vitamins was not verified. Calorimetric experiments were performed in the system ascorbic acid-riboflavin, with the aim of elucidate the transport mechanisms involved.

ASSUNTO(S)

aminoacidos micelas vitamina b2 vitamina c

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