The Experts below are selected from a list of 180 Experts worldwide ranked by ideXlab platform
M. Porcel - One of the best experts on this subject based on the ideXlab platform.
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Kinetic–spectrophotometric determination of theophylline, dyphylline, and Proxyphylline by use of partial least-squares regression
Analytical and Bioanalytical Chemistry, 2002Co-Authors: H. Iturriaga, J. Coello, S. Maspoch, M. PorcelAbstract:A kinetic–spectrophotometric method for the determination of theophylline, dyphylline and Proxyphylline, based on their azo coupling reaction with the diazonium ion of sulfanilic acid after a treatment with alkali, is proposed. The absorbance is recorded from 340 to 600 nm every second during reaction for 90 s, and calibration is performed by partial least-squares regression, using first derivative spectra values. Mixtures containing 2.5–13 µg mL^–1 dyphylline and Proxyphylline, and 2–9 µg mL^–1 theophylline were successfully resolved with root mean squared errors of prediction (RMSEP) of 0.4, 0.3, and 0.2 for dyphylline, Proxyphylline, and theophylline, respectively. The proposed method was satisfactorily applied to the determination of the three compounds in a commercially available pharmaceutical preparation and provided results similar to those obtained by HPLC.
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kinetic spectrophotometric determination of theophylline dyphylline and Proxyphylline by use of partial least squares regression
Analytical and Bioanalytical Chemistry, 2002Co-Authors: H. Iturriaga, J. Coello, S. Maspoch, M. PorcelAbstract:A kinetic–spectrophotometric method for the determination of theophylline, dyphylline and Proxyphylline, based on their azo coupling reaction with the diazonium ion of sulfanilic acid after a treatment with alkali, is proposed. The absorbance is recorded from 340 to 600 nm every second during reaction for 90 s, and calibration is performed by partial least-squares regression, using first derivative spectra values. Mixtures containing 2.5–13 µg mL–1 dyphylline and Proxyphylline, and 2–9 µg mL–1 theophylline were successfully resolved with root mean squared errors of prediction (RMSEP) of 0.4, 0.3, and 0.2 for dyphylline, Proxyphylline, and theophylline, respectively. The proposed method was satisfactorily applied to the determination of the three compounds in a commercially available pharmaceutical preparation and provided results similar to those obtained by HPLC.
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"Multi component kinetic-spectrophotometric analysis. Selection of wavelength and time ranges."
The Analyst, 2001Co-Authors: Hortensia Iturriaga, Jordi Coello, Santiago Maspoch, M. PorcelAbstract:An empirical method for the selection of the best wavelength and time ranges which can be used in the quantification of binary mixtures, in a kinetic–spectrophotometric system, is proposed. It is based on finding those ranges which provide the least correlation between the kinetic profiles and the spectra of the products of reaction. The method was applied to the analysis of binary mixtures using simulated data with different rate constant ratios and in the presence of an interference that shows spectral overlap with the analytes. Subsequently, the proposed method was applied to the resolution of dyphylline and Proxyphylline mixtures. The system studied was characterized by an elevated similarity in the kinetic behavior of the analytes under pseudo-first-order conditions and an elevated degree of spectral overlap of the products of reaction. In spite of this, satisfactory results were obtained in the quantification of the two analytes. The standard error of prediction (SEP) and the standard deviation between replicates (SDBR) did not show significant differences, being of the order of 4 and of 3% for dyphylline and Proxyphylline, respectively.
H. Iturriaga - One of the best experts on this subject based on the ideXlab platform.
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Kinetic–spectrophotometric determination of theophylline, dyphylline, and Proxyphylline by use of partial least-squares regression
Analytical and Bioanalytical Chemistry, 2002Co-Authors: H. Iturriaga, J. Coello, S. Maspoch, M. PorcelAbstract:A kinetic–spectrophotometric method for the determination of theophylline, dyphylline and Proxyphylline, based on their azo coupling reaction with the diazonium ion of sulfanilic acid after a treatment with alkali, is proposed. The absorbance is recorded from 340 to 600 nm every second during reaction for 90 s, and calibration is performed by partial least-squares regression, using first derivative spectra values. Mixtures containing 2.5–13 µg mL^–1 dyphylline and Proxyphylline, and 2–9 µg mL^–1 theophylline were successfully resolved with root mean squared errors of prediction (RMSEP) of 0.4, 0.3, and 0.2 for dyphylline, Proxyphylline, and theophylline, respectively. The proposed method was satisfactorily applied to the determination of the three compounds in a commercially available pharmaceutical preparation and provided results similar to those obtained by HPLC.
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kinetic spectrophotometric determination of theophylline dyphylline and Proxyphylline by use of partial least squares regression
Analytical and Bioanalytical Chemistry, 2002Co-Authors: H. Iturriaga, J. Coello, S. Maspoch, M. PorcelAbstract:A kinetic–spectrophotometric method for the determination of theophylline, dyphylline and Proxyphylline, based on their azo coupling reaction with the diazonium ion of sulfanilic acid after a treatment with alkali, is proposed. The absorbance is recorded from 340 to 600 nm every second during reaction for 90 s, and calibration is performed by partial least-squares regression, using first derivative spectra values. Mixtures containing 2.5–13 µg mL–1 dyphylline and Proxyphylline, and 2–9 µg mL–1 theophylline were successfully resolved with root mean squared errors of prediction (RMSEP) of 0.4, 0.3, and 0.2 for dyphylline, Proxyphylline, and theophylline, respectively. The proposed method was satisfactorily applied to the determination of the three compounds in a commercially available pharmaceutical preparation and provided results similar to those obtained by HPLC.
F. W. H. M. Merkus - One of the best experts on this subject based on the ideXlab platform.
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Chemical and biopharmaceutical aspects of theophylline and its derivatives
Current Medical Research and Opinion, 2008Co-Authors: J. Zuidema, F. W. H. M. MerkusAbstract:SummaryAlthough the N-substituted derivatives of theophylline are commonly described as ‘theophylline derivatives with uses similar to those of aminophylline’ and approximate equivalents in theophylline content are given, they have different pharmacological and pharmacokinetic properties which must be taken into account. Data on the chemical, biopharmaceutic and pharmacokinetic properties of theophylline, its salts and some N-substituted derivatives are discussed. After oral administration, theophylline and its salts, aminophylline and choline theophyllinate, arequickly andcompletely absorbedand optimal blood concentrations of theophylline (10 to 20 μg/ml) are readily attained, depending on the release characteristics of the formulation. In contrast, however, the N-substituted derivatives such as acephylline, etophylline and diprophylline, although more soluble than theophylline, are incompletely absorbed and whilst Proxyphylline is completely absorbed, none of these derivatives dissociate to theophylline...
S. Maspoch - One of the best experts on this subject based on the ideXlab platform.
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Kinetic–spectrophotometric determination of theophylline, dyphylline, and Proxyphylline by use of partial least-squares regression
Analytical and Bioanalytical Chemistry, 2002Co-Authors: H. Iturriaga, J. Coello, S. Maspoch, M. PorcelAbstract:A kinetic–spectrophotometric method for the determination of theophylline, dyphylline and Proxyphylline, based on their azo coupling reaction with the diazonium ion of sulfanilic acid after a treatment with alkali, is proposed. The absorbance is recorded from 340 to 600 nm every second during reaction for 90 s, and calibration is performed by partial least-squares regression, using first derivative spectra values. Mixtures containing 2.5–13 µg mL^–1 dyphylline and Proxyphylline, and 2–9 µg mL^–1 theophylline were successfully resolved with root mean squared errors of prediction (RMSEP) of 0.4, 0.3, and 0.2 for dyphylline, Proxyphylline, and theophylline, respectively. The proposed method was satisfactorily applied to the determination of the three compounds in a commercially available pharmaceutical preparation and provided results similar to those obtained by HPLC.
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kinetic spectrophotometric determination of theophylline dyphylline and Proxyphylline by use of partial least squares regression
Analytical and Bioanalytical Chemistry, 2002Co-Authors: H. Iturriaga, J. Coello, S. Maspoch, M. PorcelAbstract:A kinetic–spectrophotometric method for the determination of theophylline, dyphylline and Proxyphylline, based on their azo coupling reaction with the diazonium ion of sulfanilic acid after a treatment with alkali, is proposed. The absorbance is recorded from 340 to 600 nm every second during reaction for 90 s, and calibration is performed by partial least-squares regression, using first derivative spectra values. Mixtures containing 2.5–13 µg mL–1 dyphylline and Proxyphylline, and 2–9 µg mL–1 theophylline were successfully resolved with root mean squared errors of prediction (RMSEP) of 0.4, 0.3, and 0.2 for dyphylline, Proxyphylline, and theophylline, respectively. The proposed method was satisfactorily applied to the determination of the three compounds in a commercially available pharmaceutical preparation and provided results similar to those obtained by HPLC.
J. Coello - One of the best experts on this subject based on the ideXlab platform.
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Kinetic–spectrophotometric determination of theophylline, dyphylline, and Proxyphylline by use of partial least-squares regression
Analytical and Bioanalytical Chemistry, 2002Co-Authors: H. Iturriaga, J. Coello, S. Maspoch, M. PorcelAbstract:A kinetic–spectrophotometric method for the determination of theophylline, dyphylline and Proxyphylline, based on their azo coupling reaction with the diazonium ion of sulfanilic acid after a treatment with alkali, is proposed. The absorbance is recorded from 340 to 600 nm every second during reaction for 90 s, and calibration is performed by partial least-squares regression, using first derivative spectra values. Mixtures containing 2.5–13 µg mL^–1 dyphylline and Proxyphylline, and 2–9 µg mL^–1 theophylline were successfully resolved with root mean squared errors of prediction (RMSEP) of 0.4, 0.3, and 0.2 for dyphylline, Proxyphylline, and theophylline, respectively. The proposed method was satisfactorily applied to the determination of the three compounds in a commercially available pharmaceutical preparation and provided results similar to those obtained by HPLC.
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kinetic spectrophotometric determination of theophylline dyphylline and Proxyphylline by use of partial least squares regression
Analytical and Bioanalytical Chemistry, 2002Co-Authors: H. Iturriaga, J. Coello, S. Maspoch, M. PorcelAbstract:A kinetic–spectrophotometric method for the determination of theophylline, dyphylline and Proxyphylline, based on their azo coupling reaction with the diazonium ion of sulfanilic acid after a treatment with alkali, is proposed. The absorbance is recorded from 340 to 600 nm every second during reaction for 90 s, and calibration is performed by partial least-squares regression, using first derivative spectra values. Mixtures containing 2.5–13 µg mL–1 dyphylline and Proxyphylline, and 2–9 µg mL–1 theophylline were successfully resolved with root mean squared errors of prediction (RMSEP) of 0.4, 0.3, and 0.2 for dyphylline, Proxyphylline, and theophylline, respectively. The proposed method was satisfactorily applied to the determination of the three compounds in a commercially available pharmaceutical preparation and provided results similar to those obtained by HPLC.
