Copper(II) complexation properties and surfactant activity of 3-[N,N-bis(2-hydroxyethyl)amino]-2-hydroxypropanesulfonic acid and N-(2-hydroxyethyl)piperazine-N '-2-hydroxypropanesulfonic acid pH buffers which may affect trace metal speciation in in vitro studies

• Tipo: Artigo em Revista Científica Internacional
• Data: 1998

Autores

Vasconcelos, MTSD (Autor) Outra; Azenha, MAGO (Autor) Outra; Almeida, CMR (Autor) Outra

Revista

Título: Analytical Biochemistry

Vol. 265

Páginas: 193-201

ISSN: 0003-2697

Editora: Elsevier

Indexação

ISI Web of Knowledge - 29 Citações

Scopus - 30 Citações

Classificação Científica

FOS: Ciências exactas e naturais > Química

Outras Informações

ID Authenticus: P-001-6J5

DOI: 10.1006/abio.1998.2884

Abstract (EN): Disadvantages of the some zwitterionic pH buffers are (i) that they can interact with metal ions as well as protons, and (ii) that they may have a surfactant effect in chemical or in vitro biological or biochemical studies. This has to be taken into account when a buffer is selected. Here, the copper-complexing capacity and the surfactant activity of three compounds, 3-[N,N-bis (2-hydroxyethyl)amino]-2-hydroxypropanesulfonic acid (DIPSO), N-(2-hydroxyethyl)piperazine-N'-(2-hydroxypropanesulfonic acid) (HEPPSO), and piperazine-Ni,N'-bis(2-ethanesulfonic acid) (Pipes), were investigated. Global stability constants (log beta(abc)) of copper(II)-buffer complexes were determined, at 25 degrees C, 0.5 M ionic strength, and at 0.8 mM buffer concentration, by pH and pCu ion-selective electrode measurements. Here, beta(abc) corresponds to the equilibrium: aCu(2+) + bL(-) + cH(+) <-> (CUaLbHc)((2a-b+c)); HL = DIPSO or HEPPSO; c: +1 = proton; -1 = hydroxide. Using SUPERQUAD constants were calculated, giving: DIPSO: log beta(110) = 5.02, log beta(120) 8.99, log beta(130) = 13.0, log beta(140) = 16.3, log beta(14-1) = 9.26, log beta(14-2) = 0.645, log beta(150) = 20.5, log beta(160) = 24.3, log beta(16-1) 16.1, log beta(16-2) = 8.98; HEPPSO: log beta(110) = 4.29, log beta(120) = 8.35, log beta(130) = 12.1, log beta(140) = 15.9, log beta(150) = 19.6, log beta(160) = 23.4, log beta(16-1) = 14.9. The pK(a) values were determined at higher buffer concentrations, giving a value 7.33 for DIPSO and 7.84 for HEPPSO at 2.0 mM buffer concentration. Effects of buffer concentration on stability and acidity constants were investigated and compared with measurements using voltammetric and potentiometric stripping analysis, confirming no copper(II) complexation by Pipes. Surfactant activities were determined using alternating current polarography, confirming marked surface activity of 10 mM of DIPSO or HEPPSO. (C) 1998 Academic Press.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 9