Evaluation of a Fibre Optic Device in Solution Equilibria Studies. Application to 3‐Hydroxybenzoic Acid Ionization

Abstract

The use of a fibre optic device for spectrophotometric measurements in solution equilibria studies is presented. In particular the precision obtainable with such equipment is evaluated as a function of different experimental conditions, such as path length, averaging time and stirring of the solution. Analysis of 3-hydroxybenzoic acid ionization is presented to assess the results obtained in the study of an equilibrium system.

Potentiometric, spectrophotometric and calorimetric study on iron(III) and copper(II) complexes with 1,2-dimethyl-3-hydroxy-4-pyridinone

“…2 were obtained by applying evolving factor analysis (EFA) and least squares methods (SPECFIT program [19]) to the spectral data collected during the titrations. The same values, in the limits of experimental precision, were obtained by analyzing the potentiometric data alone with PSEQUAD [16] and SUPERQUAD [17] programs, and the combined spectral and potentiometric data with HYPERQUAD program [22]. These results were possible thanks to the high quality of our experimental data.…”

“…After each base addition, a time delay was given to the system for equilibration, then the potentiometric value and the corresponding spectrum were recorded; afterwards new base was added and the procedure repeated. The experimental procedure, accuracy and precision were discussed in our previous works [16][17][18]. Ionization and formation constants were calculated from spectrophotometric data by the SPECFIT [19][20][21] program and from combined spectrophotometricpotentiometric data by HYPERQUAD [22] program.…”

Iron(III) and aluminum(III) complexes with hydroxypyrone ligands aimed to design kojic acid derivatives with new perspectives

“…Accuracy and precision of this equipment were previously discussed [26]. Protonation and Fe(III) complex formation constants were determined by simultaneous potentiometric and spectrophotometric titrations, while Al(III) complex formation constants were potentiometrically determined.…”

Potentiometric and spectrophotometric equilibrium study on Fe(III) and new catechol-bisphosphonate conjugates

“…Accuracy and precision of this equipment have been discussed previously [12,13]. The spectra of the titrations of the pure ligands were recorded in the 250-400 nm spectral range, while those of iron(III) complex titrations were recorded in the 300-800 nm range.…”