References of "Chiap, Patrice"
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See detailOn-line coupling of cyclodextrin mediated nonaqueous capillary electrophoresis to mass spectrometry for the determination of salbutamol enantiomers in urine
Servais, Anne-Catherine ULg; Fillet, Marianne ULg; Mol, Roelof et al

in Journal of Pharmaceutical & Biomedical Analysis (2006), 40(3), 752-757

The usefulness of the on-line coupling of nonaqueous capillary electrophoresis (NACE) with electrospray ionization (ESI) mass spectrometry (MS) using heptakis(2,3-di-O-acetyl-6-O-sulfo)-beta-cyclodextrin ... [more ▼]

The usefulness of the on-line coupling of nonaqueous capillary electrophoresis (NACE) with electrospray ionization (ESI) mass spectrometry (MS) using heptakis(2,3-di-O-acetyl-6-O-sulfo)-beta-cyclodextrin (HDAS-beta-CD) was demonstrated for the enantioselective determination of low concentrations of salbutamol in human urine. After optimization of several parameters, such as sheath-liquid composition and flow rate, nebulizing gas pressure, CE counter-pressure and position of the CE capillary outlet, a limit of quantification of 18 and 20 ng/ml was obtained for salbutamol enantiomers. Moreover, the relative standard deviation values for repeatability at a concentration of 30 ng/ml were below 7% for both enantiomers. Typical regression lines obtained after application of a simple linear regression model revealed a pod relationship between peak area and analyte concentration (with 0.9988 and 0.9966 as coefficients of determination). This paper proposes an easy to use and sensitive NACE-MS method to determine enantiomers of a basic chiral drug in biological fluids preceded by solid-phase extraction as sample cleanup. (c) 2005 Elsevier B.V. All rights reserved. [less ▲]

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See detailLC method for the determination of R-timolol in S-timolol maleate: Validation of its ability to quantify and uncertainty assessment.
Marini Djang'Eing'A, Roland ULg; Chiap, Patrice ULg; Boulanger, Bruno ULg et al

in Talanta (2006), 68(4), 1166-1175

This article presents the validation results of a chiral liquid chromatographic (LC) method previously developed for the quantitative determination of R-timolol in S-timolol maleate samples. A novel ... [more ▼]

This article presents the validation results of a chiral liquid chromatographic (LC) method previously developed for the quantitative determination of R-timolol in S-timolol maleate samples. A novel validation strategy based on the accuracy profiles was used to select the most appropriate regression model, to assess the method accuracy within well defined acceptance limits and to determine the limits of quantitation as well as the concentration range. The validation phase was completed by the investigation of the risk profiles of various acceptable regression models in order to ensure the risk of obtaining the future measurements outside the acceptance limits fixed a priori. On the other hand, the present paper also shows how data used in this validation approach can be used to estimate the measurement uncertainty. The uncertainty derived from beta-expectation tolerance interval (sigma(Tol)(2)), which is equal to the uncertainty of measurements as well as the expanded uncertainty (U(x)) using a coverage factor k=2 was estimated. The uncertainty estimates obtained from validation data were finally compared with those obtained from interlaboratory and robustness studies. [less ▲]

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See detailPrecision study on capillary electrophoresis methods for metacycline
Do Thi, Thao; Pomponi, Romeo; Gotti, Roberto et al

in Electrophoresis (2006), 27(12), 2317-2329

A CE method for metacycline (MTC) determination was investigated in an inter-laboratory experiment. Many problems were encountered in this study, most of which were related to the transfer of the method ... [more ▼]

A CE method for metacycline (MTC) determination was investigated in an inter-laboratory experiment. Many problems were encountered in this study, most of which were related to the transfer of the method to different CE equipment. The reported problems could be classified into different categories: problems related to the precision, to the parameters in the protocol, and to the MTC peak shape. As the peak shape problem was partially responsible for the poor precision, a new CE method was developed in order to obtain a good MTC peak shape on all equipment. The precision of this new method for MTC determination was examined in an intermediate precision study, where the influence of the factors "time" and "equipment" was investigated. Although the new method could be transferred to different instruments, the precision remained poor mainly due to the contributions of the between-replicate and the between-injection variances. [less ▲]

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See detailLe transfert d'une methode de dosage automatisee de la noradrenaline dans l'urine humaine: utilisation de l'erreur totale comme critere de decision
Rozet, Eric ULg; Dewé, Walthère ULg; Chiap, Patrice ULg et al

in Acta Clinica Belgica. Supplementum (2006), (1), 57-9

Two new statistical approaches based on the total error of measurements were applied to the transfer of an automated method for the determination of noradrenalin in human urine by LC-ECD coupled on-line ... [more ▼]

Two new statistical approaches based on the total error of measurements were applied to the transfer of an automated method for the determination of noradrenalin in human urine by LC-ECD coupled on-line to SPE. They showed that the receiving laboratory was mastering the analytical procedure allowing it to use the method in routine. Furthermore the risk based approach gave guarantee that the risk to have future measurements out of specification in the receiving laboratory was smaller than 5%, therefore being a risk management tool. [less ▲]

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See detailComparaison de trois approches pour l'estimation de l'incertitude.
Marini Djang'Eing'A, Roland ULg; Chiap, Patrice ULg; Boulanger, Bruno ULg et al

in Acta Clinica Belgica. Supplementum (2006), (1), 60-2

Three different approaches for the estimation of uncertainty measurements using the same analytical method were compared, namely validation, robustness and inter-laboratory studies. The uncertainty ... [more ▼]

Three different approaches for the estimation of uncertainty measurements using the same analytical method were compared, namely validation, robustness and inter-laboratory studies. The uncertainty obtained with the robustness study! predicted well the uncertainty of the inter-laboratory study. On the other hand, the uncertainty estimation obtained with the validation study is lower than those obtained with the two other approaches but is still acceptable as long as the analytical method will be used in a single laboratory. [less ▲]

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See detailNonaqueous capillary electrophoresis method for the enantiomeric purity determination of S-timolol using heptakis(2,3-di-O-methyl-6-O-sulfo)-beta-cyclodextrin: validation using the accuracy profile strategy and estimation of uncertainty.
Marini Djang'Eing'A, Roland ULg; Servais, Anne-Catherine ULg; Rozet, Eric ULg et al

in Journal of Chromatography. A (2006), 1120(1-2), 102-11

Nonaqueous capillary electrophoresis (NACE) was successfully applied to the enantiomeric purity determination of S-timolol maleate using heptakis(2,3-di-O-methyl-6-O-sulfo)-beta-cyclodextrin (HDMS-beta-CD ... [more ▼]

Nonaqueous capillary electrophoresis (NACE) was successfully applied to the enantiomeric purity determination of S-timolol maleate using heptakis(2,3-di-O-methyl-6-O-sulfo)-beta-cyclodextrin (HDMS-beta-CD) as chiral selector. With a background electrolyte made up of a methanolic solution of 0.75 M formic acid, 30 mM potassium camphorsulfonate and containing 30 mM HDMS-beta-CD, the determination of 0.1% of R-timolol in S-timolol could be performed with an enantiomeric resolution of 8.5. Pyridoxine was selected as internal standard. The NACE method was then fully validated by applying a novel strategy using accuracy profiles. It is based on beta-expectation tolerance intervals for the total measurement error which includes trueness and intermediate precision. The uncertainty of measurements derived from beta-expectation tolerance intervals was estimated at each concentration level of the validation standards. To confirm the suitability of the developed and validated method, several real samples of S-timolol maleate containing R-timolol maleate at different concentrations were analysed and the results were compared to those obtained by liquid chromatography. [less ▲]

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See detailTransfert d’une méthode de dosage automatisée de 3 catécholamines majeures dans l’urine humaine
Rozet, Eric ULg; Dewe, W.; Morello, R. et al

Poster (2006)

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