Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.13/33461

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Title
Spectrophotometric studies on the protonation and nickel complexation equilibria of 4-(2-pyridylazo) resorcinol using global analysis in aqueous solution
Author/Creator
Ghasemi, Jahanbakhsh;  Niazi, Ali;  Maeder, Marcel
Institution
The University of Newcastle. Faculty of Science & Information Technology, School of Environmental and Life Science
Description
The protonation and Ni(II) complexation of 4-(2-pyridylazo) resorcinol (PAR) in ionic strength 0.1 mol L⁻¹ KNO₃ at 25 ℃ has been studied by global analysis. In spectrophotometric titrations, linear or near-linear dependence of concentration profiles and the existence of minor species can cause difficulties in the evaluation of the data. Both calculated absorption spectra and the corresponding equilibrium constants are not or only poorly defined. The result is the inability to reliably fit a reasonable model to the data. In second order global analysis, a number of spectrophotometric titrations with different initial concentrations are simultaneously analyzed. In this way, conditions for the significant formation of all species can be obtained and consequently the concentration matrix is augmented to full rank. EQUISPEC is a computer program using the matrix based MATLAB environment for second order global analysis of spectrophotometric equilibrium data. The spectrophotometric titrations were carried out at least in four different metal to ligand ratios.
Relation
Journal of the Brazilian Chemical Society Vol. 18, Issue 2, p. 267-272
Publisher Link
http://dx.doi.org/10.1590/S0103-50532007000200004
Date
2007
Publisher
Sociedade Brasileira de Quimica
Keyword(s)
PAR;  nickel;  protonation equilibrium;  stability constants;  global analysis;  pH-absorbance titration
Resource Type
journal article
Identifier
http://hdl.handle.net/1959.13/33461
Identifier
ISSN:0103-5053
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Subject
"Journal of the Brazilian Chemical Society"
 
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