Multiparametric curve fitting—XA structural classification of programs for analysing multicomponent spectra and their use in equilibrium-model determination

Meloun, Milan; Javůrek, Milan; Havel, Josef

doi:10.1016/0039-9140(86)80263-6

Cited by 70 publications

(42 citation statements)

References 22 publications

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“…The multicomponent spectra analysing program SQUAD(84) [8] may adjust β qr and ε qr for a given absorption spectra set by minimising the residual-square sum function, U,…”

Section: Procedures For the Determination Of The Protonationmentioning

confidence: 99%

“…Computations relating to the determination of the dissociation constants were performed by regression analysis of the UV/VIS spectra using the SQUAD(84) [8] and SPECFIT/32 [39] programs. Most of graphs were plotted using ORIGIN 7.5 [41] and S-Plus [40].…”

Section: Software Usedmentioning

confidence: 99%

“…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%

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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 multicomponent spectra analysing program SQUAD(84) [8] may adjust β qr and ε qr for a given absorption spectra set by minimising the residual-square sum function, U,…”

Section: Procedures For the Determination Of The Protonationmentioning

confidence: 99%

Section: Software Usedmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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

Self Cite

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show abstract

“…The information can be extracted if multivariate spectrophotometric data are analyzed by means of an appropriate multivariate data analysis method. Hard-modelling methods, for example SQUAD(84) [4][5][6][7][8][9][10][11], include traditional least squares curve fitting approaches, based on a previous postulation of the chemical (here protonation) model. The postulations are a set of variously protonated species defined by their stoichiometric coefficients and protonation constants, which are refined by the leastsquares minimization.…”

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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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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Interaction of dimethyltin(IV) dichloride with 5′‐IMP and 5′‐UMP

Gharib

Jaberi

Zandevakili

2008

Applied Organom Chemis

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The formation constants of the species formed in the systems H + + dimethyltin(IV) + 5 -IMP and 5 -UMP, H + + 5 -IMP and H + + 5 -UMP have been determined in aqueous solution in the pH range 1.5-9.5 at constant temperature (25• C) and constant ionic strength (0.1 mol dm −3 NaClO 4 ), using spectrophotometric and potentiometric techniques. 1 H and 31 P NMR investigations in aqueous solution confirmed the species formation. The precipitated complexes of IMP and UMP by Me 2 Sn(IV) 2+ at low pH values were characterized by elemental analysis and FTIR spectroscopy methods, the bonding sites of the ligands were determined and ruled out purine and pyrimidine moieties (N-7 and N-1 in IMP and N-3 in UMP, respectively) while a bidentated coordination of the phosphate group is concluded in both cases. Finally, the experiments revealed the existence of complexes with trigonal bipyramidal structures that is in agreement with similar systems resulted previously.

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Multiparametric curve fitting—XA structural classification of programs for analysing multicomponent spectra and their use in equilibrium-model determination

Cited by 70 publications

References 22 publications

Recent Progress in the pKa Estimation of Druglike Molecules 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

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

Interaction of dimethyltin(IV) dichloride with 5′‐IMP and 5′‐UMP

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