Calculation of equilibrium constants from multiwavelength spectroscopic data—IMathematical considerations

Gampp, Harald; Maeder, Marcel; Meyer, Charles J.; Zuberbühler, Andreas D.

doi:10.1016/0039-9140(85)80035-7

Cited by 613 publications

(506 citation statements)

References 22 publications

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“…Computations relating to the determination of dissociation constants were performed by regression analysis of the UV/VIS spectra using the SPECFIT/32 [12][13][14][15][16] programmes. Most of graphs were plotted using ORIGIN 7.5 [49] and S-Plus [50].…”

Section: Computationsmentioning

confidence: 99%

“…However, a hard-modelling analysis cannot be applied if crucial information is missing. Softmodelling or model-free approaches, for example SPECFIT [12][13][14][15][16], are based on much more general prerequisites, such as positive molar absorbance, positive concentration of all species, unimodality of concentration profiles, and closure, that is, a concentration of all species is the same for all solutions. Naturally, if the strengths of hard-modelling and soft-modelling methodologies are combined, a much more powerful method of data analysis can be expected.…”

Section: Introductionmentioning

confidence: 99%

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The Thermodynamic Dissociation Constants of Clotrimazole, Terbinafine HCL, Acetylsalicylic Acid, Salicylic Acid, and Galanthamine by the Nonlinear Regression of Multiwavelength Spectrophotometric pH-Titration Data

2010

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The mixed dissociation constants of five drugs-clotrimazole, terbinafine HCl, acetylsalicylic acid, salicylic acid, and galanthamineat various ionic strengths I and at temperatures of 25 • C and 37 • C were determined with the use of multiwavelength and multivariate treatments of spectral data SPECFIT/32 nonlinear regression analysis and INDICES factor analysis. The factor analysis in the INDICES program predicts the number of components, when the data quality is high and the instrumental error is known. The thermodynamic dissociation constant pK T a was estimated by nonlinear regression of {pK a, I} data at 25 • C and 37 • C: for clotrimazole pK T a,1 = 4.38(1) and 4.16(3); for terbinafine HCl pK T a,1 = 4.19(3) and 4.12(5); for acetylsalicylic acid pK T a,1 = 3.49(25) and 3.41(15); for salicylic acid pK T a,1 = 3.01(1) and 3.00(1) and for galanthamine pK T a,1 = 8.21(1) and 7.99(2) where in brackets the standard deviation is in the last significant digits. Goodness-of-fit tests for various regression diagnostics enabled the reliability of the parameter estimates found to be proven. Pharma Algorithms predicts pK a being based on the structural formulae of drug compounds.

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Section: Computationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The Thermodynamic Dissociation Constants of Clotrimazole, Terbinafine HCL, Acetylsalicylic Acid, Salicylic Acid, and Galanthamine by the Nonlinear Regression of Multiwavelength Spectrophotometric pH-Titration Data

2010

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“…Much more information can be extracted if multivariate spectrophotometric data are analyzed by means of an appropriate multivariate data analysis method cf. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. In previous work [21][22][23][24][25][26][27][28][29][30][31][32][33], the authors have shown that the spectrophotometric method can be used in combination with suitable chemometric tools for the determination of protonation constants β qr or acid dissociation constants pK a , even for sparingly soluble drugs.…”

Section: Introductionmentioning

confidence: 99%

“…These mathematical procedures require the fulfillment of the mass-balance equations and the massaction law. The most relevant algorithms are SQUAD(84) [6][7][8][9][10][11] and SPECFIT32 [14][15][16][17]39].…”

Section: Introductionmentioning

confidence: 99%

Recent Progress in the pKa Estimation of Druglike Molecules by the Nonlinear Regression of Multiwavelength Spectrophotometric pH-Titration Data

Meloun¹,

Syrový²,

Ghasemi³

2010

SRX Pharmacology

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.Recent developments in the computational diagnostic tools for the pK a estimation of druglike molecules carried out by the nonlinear regression of multiwavelength spectrophotometric pH-titration data are demonstrated on the protonation equilibria of silybin. The factor analysis of spectra predict the correct number of components when the signal-to-error ratio SER is higher than 10. The mixed dissociation constants of the drug silybin at ionic strength I = 0.03 and a temperature of 25• C were determined using two different programs, SPECFIT32 and SQUAD(84). A proposed experimental and computational strategy for the determination of the dissociation constants is presented. The dissociation constant pK a was estimated by nonlinear regression of the {pK a , I} data at 25• C with SQUAD (and SPECFIT); that is, pK a1 = 6.898(0.022) and 6.897(0.002); pK a2 = 8.666(0.021) and 8.667(0.012); pK a3 = 9.611(0.010) and 9.611(0.004); pK a4 = 11.501(0.008) and 11.501(0.007). While great progress has been achieved in terms of the reliability of the protonation model estimation, among the most efficient diagnostics of the nonlinear regression of multiwavelength pH-spectra are the goodness-of-fit test, Cattel's scree plot of the factor analysis, spectra deconvolution, the signal-to-error SER ratio analysis, and other tools of efficient spectra analysis.

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“…The essential details of the software and the involved non-linear algorithms are given in literatures. [14][15][16][17] …”

Section: Apparatusmentioning

confidence: 99%

Spectrophotometric Titration of Cobalt(II) with CaCl2 in Mixed Solvents of 2-Propanol and Water for the Analysis of the Extraction Mechanism of Cobalt(II) by Salting-out in the Presence of CaCl2

Chung

Tabata

2005

ANAL. SCI.

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Calculation of equilibrium constants from multiwavelength spectroscopic data—IMathematical considerations

Cited by 613 publications

References 22 publications

The Thermodynamic Dissociation Constants of Clotrimazole, Terbinafine HCL, Acetylsalicylic Acid, Salicylic Acid, and Galanthamine by the Nonlinear Regression of Multiwavelength Spectrophotometric pH-Titration Data

The Thermodynamic Dissociation Constants of Clotrimazole, Terbinafine HCL, Acetylsalicylic Acid, Salicylic Acid, and Galanthamine by the Nonlinear Regression of Multiwavelength Spectrophotometric pH-Titration Data

Recent Progress in the pKa Estimation of Druglike Molecules by the Nonlinear Regression of Multiwavelength Spectrophotometric pH-Titration Data

Spectrophotometric Titration of Cobalt(II) with CaCl2 in Mixed Solvents of 2-Propanol and Water for the Analysis of the Extraction Mechanism of Cobalt(II) by Salting-out in the Presence of CaCl2

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