EPSILON: a versatile microcomputer program for the spectrophotometric data analysis of metal–ligand equilibria

Araujo, César L.; Ibáñez, Guillermo; Ledesma, Gabriela N.; Escandar, Graciela M.; Olivieri, Alejandro C.

doi:10.1016/s0097-8485(97)00061-2

Cited by 12 publications

(6 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The equilibrium constant determinations were carried out by using the program EPSI-LON. 29,30 † Concentrations of ternary complexes as a function of the analytical concentrations of reagents, useful for constructing three-dimensional and contour plots, were calculated with suitable MATLAB 5.3 routines (The Mathworks, South Natick, MA, 1994). The calibration data were analyzed with the aid of the program ALAM-IN.…”

Section: Experim Entalmentioning

confidence: 99%

Room-Temperature Phosphorescence of 1-Bromonaphthalene upon Formation of Beta-Cyclodextrin Ternary Complexes with Alcohols and Surfactants: Optimization of Analytical Figures of Merit by Rigorous Equilibrium Studies

Escandar¹,

Peña²

2001

Appl Spectrosc

Self Cite

View full text Add to dashboard Cite

Room-temperature phosphorimetry of ternary β-cyclodextrin complexes of the model compound 1-bromonaphthalene has been examined. The selected third partners were alcohols (cyclohexanol, cyclopentanol, and 1-pentanol) and surfactants (Triton X-100 and sodium dodecyl sulfate). A thorough analysis of all equilibria involved in the interaction between the components is performed and discussed. A computational procedure, not previously employed to study this type of complex systems, is used for the determination of the equilibrium constants and stoichiometries of the formed species. It is shown that a rigorous analysis of the equilibria is necessary for a proper optimization of analytical methods based on roomtemperature phosphorescence of ternary complexes. The best working conditions are inferred from the examination of three-dimensional and contour plots of the ternary complex concentration as a function of those of the reagents. The latter plots are constructed once the relative stabilities of all intervening species are known. On the basis of the calibration results, the relative advantages of employing the examined systems for determining the studied compound are presented.

show abstract

Section: Experim Entalmentioning

confidence: 99%

Room-Temperature Phosphorescence of 1-Bromonaphthalene upon Formation of Beta-Cyclodextrin Ternary Complexes with Alcohols and Surfactants: Optimization of Analytical Figures of Merit by Rigorous Equilibrium Studies

Escandar¹,

Peña²

2001

Appl Spectrosc

Self Cite

View full text Add to dashboard Cite

show abstract

“…These calculations were performed by using the program EPSILON. 31 Standard deviations for the reported constants refer only to random errors. 29 In the absorbance measurements concerning the diclofenacb-CD complexes, the diclofenac concentration was held constant at 3.10 3 10 25 mol l 21 while the b-CD concentration was varied from 0 to 1.00 3 10 22 mol l 21 .…”

Section: Spectrophotometric Measurementsmentioning

confidence: 99%

Complexation study of diclofenac with β-cyclodextrin and spectrofluorimetric determination

Arancibia¹,

Escandar²

1999

Analyst

Self Cite

View full text Add to dashboard Cite

The inclusional complexation between the anti-inflammatory pharmaceutical diclofenac and beta-cyclodextrin (beta-CD) was studied by potentiometry, spectrophotometry and spectrofluorimetry, in both acid and neutral pH. Guest-host 1:1 stoichiometries for the complexes in both media were determined, and their equilibrium constants were calculated. The values obtained from the different methods used are in very good agreement and are in the order of 10(3). From the analysis of the pKa value for diclofenac in both the absence and presence of beta-CD (4.84 and 4.90 respectively), it was inferred that in the inclusion complex the carboxylic group is located outside the cavity. Further structural characterization of the inclusate was carried out by means of 1H NMR spectra and AM1 semiempirical calculations. Based on the obtained results, a spectrofluorimetric method for the determination of diclofenac in the presence of beta-CD was developed in the range of 0-5 micrograms ml-1. Better limits of detection (0.03 microgram ml-1) and quantification (0.1 microgram ml-1) were obtained in this latter case with respect to those obtained in the absence of beta-CD. The method was satisfactorily applied to the quantification of diclofenac in pharmaceutical preparations.

show abstract

“…These calculations were performed with the aid of the program EPSILON, adapted to fluorescence measurements. 20 Standard deviations for the reported constants refer only to random errors. 21…”

Section: Influence Of Phmentioning

confidence: 99%

Spectrofluorimetric determination of piroxicam in the presence and absence of β-cyclodextrin

Escandar¹

1999

Analyst

Self Cite

View full text Add to dashboard Cite

The complexation between beta-cyclodextrin (beta-CD) and piroxicam (PX) was investigated by both fluorescence and absorption spectrometry. A 1:2 guest:host stoichiometry for the complex was established, and its association constant was calculated by applying a non-linear regression method to the changes brought about by the presence of beta-CD in both the fluorescence and absorbance spectra of PX. During the study of the influence of the pH on the fluorescence emission of the complex, an efficient enhancement of the signals at acidic pH was observed. This suggests that the protonated form of PX is included more effectively than the ionized form in the beta-CD cavity. Based on the results obtained, spectrofluorimetric methods for the determination of PX were developed. The best limits of detection and quantification were obtained using beta-CD at an acidic pH. The dynamic range in this latter case was 0.02-1 microgram ml-1. The method was applied satisfactorily to the determination of piroxicam in a pharmaceutical preparation.

show abstract

EPSILON: a versatile microcomputer program for the spectrophotometric data analysis of metal–ligand equilibria

Cited by 12 publications

References 28 publications

Room-Temperature Phosphorescence of 1-Bromonaphthalene upon Formation of Beta-Cyclodextrin Ternary Complexes with Alcohols and Surfactants: Optimization of Analytical Figures of Merit by Rigorous Equilibrium Studies

Room-Temperature Phosphorescence of 1-Bromonaphthalene upon Formation of Beta-Cyclodextrin Ternary Complexes with Alcohols and Surfactants: Optimization of Analytical Figures of Merit by Rigorous Equilibrium Studies

Complexation study of diclofenac with β-cyclodextrin and spectrofluorimetric determination

Spectrofluorimetric determination of piroxicam in the presence and absence of β-cyclodextrin

Contact Info

Product

Resources

About