RESUMO
In this work, a characterization of reagent chromophore 5-(4-sulphophenylazo)-8-aminoquinoline [SPA] by IR and 1H RMN was carried out and a pK(a) value of 3.55+/-0.03 was found as well. An 1:2 stoichiometry for the Cu(II)-SPA complex was determined at pH 9 by Job and molar ratio methods. A value of 1.4 x 10(14) for the stability constant was also found. Based on the formation of this complex a new method for the copper determination in presence of gold and silver was developed by derivative spectrophotometry using a previous preconcentration on solid phase. In this method, the analytical measures were executed directly in the solid phase containing the complex. The Cu(II) reacts with the reagent chromophore SPA previously retained in the anionic exchange DEAE Sephadex A25. In this determination, the first derivative at 605 nm was used. The quantification range was between (3.2+/-0.3 x 10(-1)) x 10(-8) and (94.4+/-0.9) x 10(-8) mol L(-1) (3.2+/-0.3 x 10(-1)) x 10(-8), and (94.4+/-0.9) x 10(-8) mol L(-1). The repeatability expressed as RSD was between 1.1 and 2.0%. The method was applied successfully for the copper determination in mineral residuals and natural water samples. The results were consistent with those provided by ICP-mass spectrometry.
Assuntos
Aminoquinolinas/química , Cobre/análise , Ouro/química , Prata/química , Poluentes Químicos da Água/análise , Cobre/química , DEAE-Dextrano/análogos & derivados , DEAE-Dextrano/química , Concentração de Íons de Hidrogênio , Poluentes Químicos da Água/químicaRESUMO
Benzhydrylamine-resin (BHAR), a copolymer of styrene-divinylbenzene containing phenylmethylamine groups, used as solid support for peptide synthesis, was examined regarding physicochemical and anion exchanger chromatographic properties. The greater the ionic strength of the medium the poorer the solvation of beads. This effect is less pronounced the higher the amino group content of BHAR. The BHAR chromatographic behavior was compared with commercial cationic resins in columns of constant cation binding capacity. Three negatively charged heparan sulfate disaccharides were successfully purified in a 2.4 mmol/g BHAR that showed as good or better anion exchange performance than classical tertiary or quaternary amino group-containing resins. The BHAR chromatographic resin exclusion limit was estimated to be 30 kDa based on purification experiments of heparins of different molecular weight.
Assuntos
Resinas de Troca Aniônica/química , Compostos Benzidrílicos/química , DEAE-Dextrano/análogos & derivados , Aminas/química , Cromatografia por Troca Iônica/métodos , DEAE-Dextrano/química , Dissacarídeos/isolamento & purificação , Heparina/análogos & derivados , Peso Molecular , Concentração Osmolar , Solventes/químicaRESUMO
This report demonstrates that due to the presence of residual reactive sites in their matrices, classical diethylaminoethyl-attaching commercial anion-exchanger resins such as DEAE-MacroPrep and DEAE-Sephadex A50 supports can be used for peptide synthesis. Moreover, due to the high stability of the peptide-resin bond in the final cleavage treatments, desired peptidyl-resins free of side-chain protecting groups, which enables them to be further used as solid support for affinity chromatography, can be obtained. To demonstrate this potentiality, a fragment corresponding to the antigenic and immunodominant epitope of sporozoites of the Plasmodium falciparum malaria parasite was synthesized in these traditional resins and antibody molecules generated against the peptide sequence were successfully retained in these peptidyl supports. Due to the maintenance of their original anion-exchange capacities, the present findings open the unique possibility of applying, simultaneously, dual anion-exchange and affinity procedures for purification of a variety of macromolecules.