References of "Rudaz, S"
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See detailRetention modeling and method development in hydrophilic interaction chromatography
Tyteca, Eva ULiege; Périat, A.; Rudaz, S. et al

in Journal of Chromatography. A (2014), 1337

In the present study, the possibility of retention modeling in the HILIC mode was investigated, testing several different literature relationships over a wide range of different analytical conditions ... [more ▼]

In the present study, the possibility of retention modeling in the HILIC mode was investigated, testing several different literature relationships over a wide range of different analytical conditions (column chemistries and mobile phase pH) and using analytes possessing diverse physico-chemical properties. Furthermore, it was investigated how the retention prediction depends on the number of isocratic or gradient trial or initial scouting runs. The most promising set of scouting runs seems to be a combination of three isocratic runs (95, 90 and 70%ACN) and one gradient run (95 to 65%ACN in 10min), as the average prediction errors were lower than using six equally spaced isocratic runs and because it is common in Method development (MD) to perform at least one scouting gradient run in the screening step to find out the best column, temperature and pH conditions. Overall, the retention predictions were much less accurate in HILIC than what is usually experienced in RPLC. This has severe implications for MD, as it restricts the use of commercial software packages that require the simulation of the retention of every peak in the chromatogram. To overcome this problem, the recently proposed predictive elution window shifting and stretching (PEWS2) approach can be used. In this computer-assisted MD strategy, only an (approximate) prediction of the retention of the first and the last peak in the chromatogram is required to conduct a well-targeted trial-and-error search, with suggested search conditions uniformly covering the entire possible search and elution space. This strategy was used to optimize the separation of three representative pharmaceutical mixtures possessing diverse physico-chemical properties (pteridins, saccharides and cocktail of drugs/metabolites). All problems could be successfully handled in less than 2.5h of instrument time (including equilibration). © 2014 Elsevier B.V. [less ▲]

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See detailPredictive elution window stretching and shifting as a generic search strategy for automated method development for liquid chromatography
Tyteca, Eva ULiege; Liekens, A.; Clicq, D. et al

in Analytical Chemistry (2012), 84(18), 7823-7830

We report on the possibilities of a new method development (MD) algorithm that searches the chromatographic parameter space by systematically shifting and stretching the elution window over different ... [more ▼]

We report on the possibilities of a new method development (MD) algorithm that searches the chromatographic parameter space by systematically shifting and stretching the elution window over different parts of the time-axis. In this way, the search automatically focuses on the most promising areas of the solution space. Since only the retention properties of the first and last eluting compounds of the sample need to be (approximately) known, the algorithm can be directly applied to samples with unknown composition, and the proposed solutions are not sensitive to any modeling errors. The search efficiency of the algorithm has been evaluated on an extensive set of random-generated in silico samples covering a broad range of different retention properties. Compared to a pure grid-based search, the algorithm could reduce the number of missed components by 50% and more. The algorithm has also been applied to solve three different real-world separation problems from the pharmaceutical industry. All problems could be successfully solved in a very short time (order of 12 h of instrument time). © 2012 American Chemical Society. [less ▲]

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See detailChapter 3 Method Transfer Between Conventional HPLC and UHPLC
Debrus, Benjamin ULiege; Rozet, Eric ULiege; Hubert, Philippe ULiege et al

in Guillarme, Davy; Veuthey, jean-Luc (Eds.) UHPLC in Life Sciences (2012)

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See detailEvaluating the reliability of analytical results using a probability criterion: a Bayesian perspective
Rozet, Eric ULiege; Govaerts, B.; Lebrun, Pierre ULiege et al

in Analytica Chimica Acta (2011), 705

Methods validation is mandatory in order to assess the fitness of purpose of the developed analytical method. Of core importance at the end of the validation is the evaluation of the reliability of the ... [more ▼]

Methods validation is mandatory in order to assess the fitness of purpose of the developed analytical method. Of core importance at the end of the validation is the evaluation of the reliability of the individual results that will be generated during the routine application of the method. Regulatory guidelines provide a general framework to assess the validity of a method, but none address the issue of results reliability. In this study, a Bayesian approach is proposed to address this concern. Results reliability is defined here as “the probability of an analytical method to provide analytical results within predefined acceptance limits around their reference or conventional true concentration values over a defined concentration range and under given environmental and operating conditions.” By providing the minimum reliability probability needed for the subsequent routine application of the method, as well as specifications or acceptance limits , the proposed Bayesian approach provides the effective probability of obtaining reliable future analytical results over the whole concentration range investigated. This is summarized in a single graph: the reliability profile. This Bayesian reliability profile is also compared to two frequentist approaches, the first one derived from the work of Dewé et al. [Dewé W., Govaerts B., Boulanger B., Rozet E., Chiap P., Hubert Ph., Chemometr. Intell. Lab. Syst. 85 (2007) 262-268] and the second proposed by Govaerts et al. [B. Govaerts, W. Dewé, M. Maumy, B. Boulanger, Qual. Reliab. Engng. Int. 24 (2008) 667-680]. Furthermore, to illustrate the applicability of the Bayesian reliability profile, this approach is also applied here to a bioanalytical method dedicated to the determination of ketoglutaric acid (KG) and hydroxymethylfurfural (HMF) in human plasma by SPE-HPLC-UV. [less ▲]

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See detailModels to estimate overall analytical measurements uncertainty: assumptions, comparisons and applications
Rozet, Eric ULiege; Rudaz, S.; Marini Djang'Eing'A, Roland ULiege et al

in Analytica Chimica Acta (2011), 702

Evaluation of analytical results reliability is of core importance as crucial decisions are taken with them. From the various methodologies to evaluate the fitness of purpose of analytical methods ... [more ▼]

Evaluation of analytical results reliability is of core importance as crucial decisions are taken with them. From the various methodologies to evaluate the fitness of purpose of analytical methods, overall measurement uncertainty estimation is more and more applied. Overall measurement uncertainty allows to combine simultaneously the remaining systematic influences to the random sources of uncertainty and allows assessing the reliability of results generated by analytical methods. However there are various interpretations on how to estimate overall measurement uncertainty, and thus various models for estimating it. Each model together with its assumptions has great impacts on the risks to abusively declare that analytical methods are suitable for their intended purpose. This review paper aims at i) summarizing the various models used to estimate overall measurement uncertainty, ii) provide their pros and cons, iii) review the main areas of application and iv) as a conclusion provide some recommendations when evaluating overall measurement uncertainty. [less ▲]

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See detailGuidelines and Validation Issues in Pharmaceutical Analysis
Rozet, Eric ULiege; Rudaz, S.

Conference (2010, June 16)

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See detailUniversal applicability of Total Error for the validation of bioanalytical methods
Rozet, Eric ULiege; Boulanger, Bruno ULiege; Rudaz, S. et al

Conference (2009)

An innovative universal strategy using Total Error is thus proposed to decide about the method’s validity that controls the risk of accepting an unsuitable assay together with the ability to predict the ... [more ▼]

An innovative universal strategy using Total Error is thus proposed to decide about the method’s validity that controls the risk of accepting an unsuitable assay together with the ability to predict the reliability of future results. Several examples of applications of this validation methodology to various types of assays [LC-MS, ELISA, Bio-Assays] will be presented. [less ▲]

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See detailTotal Error for the validation of bioanalytical methods
Rozet, Eric ULiege; Boulanger, Bruno ULiege; Rudaz, S. et al

Conference (2009)

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See detailEvaluation of decision methodologies for analytical method validation
Rozet, Eric ULiege; Rudaz, S.; Bouabidi, A. et al

Poster (2009)

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See detailTotal Error for the Valildation of Bioanalytical methods
Rozet, Eric ULiege; Boulanger, Bruno ULiege; Rudaz S et al

in Annales de Toxicologie Analytique (2009), 21(S1), 35

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