Influence of different sources of error on estimated kinetics parameters for a second-order reaction

Carvalho, Antonio R.; Brereton, Richard G.; Thurston, Tom J.; Escott, Richard

doi:10.1016/j.chemolab.2003.12.002

Cited by 11 publications

(10 citation statements)

References 17 publications

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“…The pharmaceutical industry, driven by the FDA ' s PAT initiative, can be seen as a forerunner. This is refl ected by the observation that many references in this chapter are (co -) authored by representatives from pharmaceutical companies like Glaxo Wellcome 21,29 and GlaxoSmithKline, 8,10,36,39,40 Astra Zeneca, 19,38 Novartis 28 and Eli Lilly. 18 As with other spectroscopic techniques, UV -vis spectroscopy can readily be used in lab -based R & D. The implementation as process monitors, scanning for deviations from the set state, is certainly an added value and low in maintenance requirements.…”

Section: Resultsmentioning

confidence: 99%

“…The extraction of kinetic parameters from in -line UV -vis spectroscopy may suffer from three sources of error: namely, instrumental noise, error in determining initial concentrations, and error in the calibration of pure standards, as is pointed out by Carvalho et al 36 These authors have studied the infl uence of these errors on the determined rate constants for a simulated second -order reaction and compared twelve methods to cope with the errors in fi ve groups. They fi nd signifi cant differences in accuracy and precision.…”

Section: Reaction Monitoringmentioning

confidence: 99%

See 1 more Smart Citation

UV‐Visible Spectroscopy for On‐Line Analysis

Liauw

Baylor

O'Rourke

2010

Process Analytical Technology

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Section: Resultsmentioning

confidence: 99%

Section: Reaction Monitoringmentioning

confidence: 99%

UV‐Visible Spectroscopy for On‐Line Analysis

Liauw

Baylor

O'Rourke

2010

Process Analytical Technology

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“…Investigating reactions to obtain kinetic information such as rate constants is a useful and common approach in modern chemistry [1][2]. Therefore, reaction rate methods are becoming increasingly important in analytical chemistry.…”

Section: Introductionmentioning

confidence: 99%

“…Established kinetic (hard) and partial least squares (soft) modeling chemometric methods were applied to both datasets to compare the information acquired with each probe. Carvalho et al [2] also investigated the influence of three sources of error, namely, instrumental noise, error in determining initial concentrations and calibration of pure standards, and the determination of rate constants from the resultant spectra for the second-order reactions. Twelve methods involving a mixture of multivariate and kinetic models for estimating rate constants were compared in five groups (MLR, Rank Augmentation, Difference Spectra, Mixed Spectra and PCR).…”

Section: Introductionmentioning

confidence: 99%

Estimation of the rate constants of second order reactions using mean centering of ratio spectra

Gorji

Bahram

Golshan

2010

JICS

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A new application of the mean centering of ratio spectra method is proposed for estimation of the rate constants of second order reactions, using kinetic-spectrophotometric data. The method is based on the mean centering of the ratio spectra to obtain a kinetic profile of the product. Using computational fitting, the rate constant can be obtained without any ambiguity. An interesting feature of second-order reactions is that the number of steps in the reaction is less than the number of absorbing species, resulting in a rank-deficient response matrix. Through using row mean centering of ratio spectra, the pure response of the product of the reaction could be obtained, and thus an accurate estimation of rate constant would be possible. The applicability of the method was evaluated by using several model data. The reaction of 1,2-naphthoquinone-4-sulfonate sodium (NQS) and 3-nitroaniline (TNA) in ethanol as a real system was also studied applying the proposed method.

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“…However, this calculation systematically underestimates this uncertainty when compared to the one resulting from multiple repetitions of the experiment under the same conditions. Some other contributions to the uncertainty in the rate constants, such as baseline shifts [26,27], spectral constraints in the least squares [28] and preceding calibration procedures [29] have been studied. Also, bootstrapping has been compared to variance-covariance based uncertainty calculations [30].…”

Section: Introductionmentioning

confidence: 99%

Uncertainties and error propagation in kinetic hard-modelling of spectroscopic data

Billeter

Neuhold

Simon

et al. 2008

Chemometrics and Intelligent Laboratory Systems

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A novel method is presented for the rigorous propagation of uncertainties in initial concentrations and in dosing rates into the errors in the rate constants fitted by multivariate kinetic hard-modelling of spectroscopic data using the Newton-Gauss-Levenberg/Marquardt optimisation algorithm. The method was successfully validated by Monte-Carlo sampling. The impact of the uncertainties in initial concentrations and in the dosing rate was quantified for simulated spectroscopic data based on a second and a formal third order rate law under batch and semi-batch conditions respectively. An important consequence of this study regarding optimum experimental design is the fact that the propagated error in a second order rate constant is minimal under exact stoichiometric conditions or when the reactant with the lowest associated uncertainty in its initial concentration is in a reasonable excess (pseudo first order conditions). As an experimental example, the reaction of benzophenone with phenylhydrazine in THF was investigated repeatedly (17 individual experiments) by UV-vis and mid-IR spectroscopy under the same semi-batch conditions, dosing the catalyst acetic acid. For all experiments and spectroscopic signals, reproducible formal third order rate constants were determined. Applying the proposed method of error propagation to any single experiment, it was possible to predict 80% (UV-vis) and 40% (mid-IR) of the observed standard deviation in the rate constants obtained from all experiments. The largest contribution to this predicted error in the rate constant could be assigned to the dosing rate. The proposed method of error propagation is flexible and can straightforwardly be extended to propagate other possible sources of error.

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Influence of different sources of error on estimated kinetics parameters for a second-order reaction

Cited by 11 publications

References 17 publications

UV‐Visible Spectroscopy for On‐Line Analysis

UV‐Visible Spectroscopy for On‐Line Analysis

Estimation of the rate constants of second order reactions using mean centering of ratio spectra

Uncertainties and error propagation in kinetic hard-modelling of spectroscopic data

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