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ABSTRACT: Evolutionary factor analysis (EFA) and rank annihilation factor analysis (RAFA) were applied to resolve the two-way equilibrium spectrophotometric data belonging to the complexes of Fe(III), Al(III) and V(V) with morin (3,5,7,20,40-penta hydroxy flavone) as chelating agent in triton X-100 micellar media. Then, partial least square regression combined with genetic algorithm for wavelength selection (GA-PLS) was used for simultaneous determination of the metal ions. The parameters controlling behavior of the system were investigated and optimum conditions were selected. The predictive abilities of partial least squares regression (PLS) and genetic algorithm-partial least squares regression (GA-PLS) were examined in simultaneous determination of ternary mixtures of metal ions over the concentration range of 17.0-170.0ngml(-1), 25.0-180.0ngml(-1) and 40.0-325.0ngml(-1) for Fe(III), Al(III) and V(V), respectively. The relative standard errors for prediction of the ions in synthetic mixtures were lower than 5% and the mean recoveries in the tap water spiked samples were 104.2 and 101.7% for PLS and GA-PLS, respectively.
Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 10/2008; 70(4):824-34. · 2.10 Impact Factor
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ABSTRACT: In order to accurately simulate (13)C NMR spectra of hydroxy, polyhydroxy and methoxy substituted flavonoid a quantitative structure-property relationship (QSPR) model, relating atom-based calculated descriptors to (13)C NMR chemical shifts (ppm, TMS=0), is developed. A dataset consisting of 50 flavonoid derivatives was employed for the present analysis. A set of 417 topological, geometrical, and electronic descriptors representing various structural characteristics was calculated and separate multilinear QSPR models were developed between each carbon atom of flavonoid and the calculated descriptors. Genetic algorithm (GA) and multiple linear regression analysis (MLRA) were used to select the descriptors and to generate the correlation models. Analysis of the results revealed a correlation coefficient and root mean square error (RMSE) of 0.994 and 2.53ppm, respectively, for the prediction set.
Journal of molecular graphics & modelling 04/2008; 27(2):105-15. · 2.17 Impact Factor
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ABSTRACT: Net analyte signal (NAS)-based multivariate calibration methods were employed for simultaneous determination of anthazoline and naphazoline. The NAS vectors calculated from the absorbance data of the drugs mixture were used as input for classical least squares (CLS), principal component and partial least squares regression PCR and PLS methods. A wavelength selection strategy was used to find the best wavelength region for each drug separately. As a new procedure, we proposed an experimental design-neural network strategy for wavelength region optimization. By use of a full factorial design method, some different wavelength regions were selected by taking into account different spectral parameters including the starting wavelength, the ending wavelength and the wavelength interval. The performance of all the multivariate calibration methods, in all selected wavelength regions for both drugs, was evaluated by calculating a fitness function based on the root mean square error of calibration and validation. A three-layered feed-forward artificial neural network (ANN) model with back-propagation learning algorithm was employed to model the nonlinear relationship between the spectral parameters and fitness of each regression method. From the resulted ANN models, the spectral regions in which lowest fitness could be obtained were chosen. Comparison of the results revealed that the net NAS-PLS resulted in lower prediction error than the other models. The proposed NAS-based calibration method was successfully applied to the simultaneous analyses of anthazoline and naphazoline in a commercial eye drop sample.
Talanta 03/2006; 68(4):1222-9. · 3.79 Impact Factor
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Internet Electronic Journal of Molecular Design J. Mol. Des. 01/2005; 4(4):882-910.
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ABSTRACT: The potential usefulness of some newly proposed topological indices (Sh indices) has been examined by their application to the prediction of 15 different properties of a large number of alkanes (C2 through C10, a total of 149 molecules). Ten different indices (Sh1 through Sh10) and a novel one (Sh index) were calculated for each molecule by different combination of the connectivity and distance sum vectors. The alkanes' properties studied included boiling point (BP), density (D), molar refraction (MR), refraction index (RI), critical temperature (CT), critical pressure (CP), surface tension (ST), molar volume (MV), heat capacity (HC), enthalpy (E), heat of vaporization (HV), heat of atomization (HA), standard heat of formation (HF), heat of formation in liquid (HFL), and heat of formation in gas (HFG). First, the novel Sh index and the Randic connectivity index were used to simply correlate them to the properties of alkane molecules. Except with D, ST and RI, in all other cases, the Sh index produced high correlation coefficients. Besides, in almost all cases, the Sh index resulted in higher correlations than the Randic index. In order to predict the properties of alkanes more accurately, the PCR analysis was employed to drive multiparametric equations between the Sh indices and alkane properties. It was found that the stepwise procedure for factor selection, which was in accordance with the correlation ranking procedure, produced more convenient models in comparison with the eigen-value ranking procedure. The advantages of the resulting QSPR models obtained by the use of Sh indices, over some other proposed models, were lower number of variables and higher prediction power.
QSAR & Combinatorial Science 11/2004; 23(9):734 - 753. · 1.55 Impact Factor
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ABSTRACT: The partial least squares regression method (PLS) was tested as a calibration procedure for the simultaneous determination of phenol, o-nitrophenol, m-nitrophenol and p-nitrophenol by both conventional and first derivative UV/Vis spectrophotometry. The experiments were conducted in the acidic, neutral and basic media. The results obtained by the application of the PLS procedure on the conventional and first derivative spectra in two solvent media were compared. It was found that the results obtained in the basic medium have better performance characteristics than those obtained in the acidic or neutral media. Comparable results were obtained in the case of both conventional and first derivative absorbance data. The proposed method was applied to the determination of the four phenol derivatives in natural spiked water samples at concentration levels between 1.0 and 10.0 microg ml(-1) with average recoveries in the range 96% - 99%.
Annali di Chimica 95(1-2):63-76. · 0.99 Impact Factor
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ABSTRACT: A novel net analyte signal standard addition method (NASSAM) was used for simultaneous determination of the drugs anthazoline and naphazoline. The NASSAM can be applied for determination of analytes in the presence of known interferents. The proposed method is used to eliminate the calibration and prediction steps of multivariate calibration methods; the determination is carried out in a single step for each analyte. The accuracy of the predictions against the H-point standard addition method is independent of the shape of the analyte and interferent spectra. The net analyte signal concept was also used to calculate multivariate analytical figures of merit, such as LOD, selectivity, and sensitivity. The method was successfully applied to the simultaneous determination of anthazoline and naphazoline in a commercial eye drop sample.
Journal of AOAC International 93(6):1995-2001. · 1.20 Impact Factor
