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See detailDevelopment of a mass spectrometry method for the determination of a melanoma biomarker, 5-S-cysteinyldopa, in human plasma using solid phase extraction for sample clean-up.
Martin, Gaëlle ULg; Chiap, Patrice ULg; Paquet, Philippe ULg et al

in Journal of Chromatography. A (2007), 1156(1-2), 141-8

5-S-cysteinyldopa is a well-known pigment intermediate and analysis of its plasma concentration is interesting for the early diagnosis, as well as for evaluation of treatment and follow-up of malignant ... [more ▼]

5-S-cysteinyldopa is a well-known pigment intermediate and analysis of its plasma concentration is interesting for the early diagnosis, as well as for evaluation of treatment and follow-up of malignant melanoma. A determination method of 5-SCD in human plasma was developed using solid phase extraction (SPE) on disposable cartridges and liquid chromatography electrospray mass spectrometry (LC-ESI-MS-MS). Compound's sensitivity to light and oxidation requires the addition of anti-oxidative agents (AO), to work in acidic media at 4 degrees C and to avoid light exposure of samples since blood collection. Different solid phases involving covalent binding to phenylboronic groups or dual retention mechanisms were evaluated and extraction cartridges containing both hydrophobic and strong cation exchange functionalities were finally selected. The LC separation of 5-SCD from endogenous catecholamines was achieved by gradient elution on a C18 stationary phase. 5-SCD was detected by multiple reaction monitoring (MRM) performed on ES(+) generated ions. Finally, the method was prevalidated in the lower ng/ml range. Good results with respect to accuracy, trueness and precision were obtained. [less ▲]

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See detailRobustness testing of a chiral NACE method for R-timolol determination in S-timolol maleate and uncertainty assessment from quantitative data.
Marini Djang'Eing'A, Roland ULg; Rozet, Eric ULg; Vanderheyden, Yvan et al

in Journal of Pharmaceutical & Biomedical Analysis (2007), 44(3), 640-51

A robustness test of a capillary electrophoresis method for the chiral separation of timolol in nonaqueous acidified media was performed. A two-level Plackett-Burman design was applied in which one ... [more ▼]

A robustness test of a capillary electrophoresis method for the chiral separation of timolol in nonaqueous acidified media was performed. A two-level Plackett-Burman design was applied in which one qualitative and six quantitative factors were examined. Resolution, migration times and relative migration times to pyridoxine (selected as internal standard) were examined as qualitative responses to evaluate electrophoretic performance. A quantitative response, the content of R-timolol in S-timolol maleate sample, was also considered. Even though some significant factor effects were observed on the qualitative responses, it was still possible to quantify the R-timolol in the S-timolol maleate samples properly. The quantitative response was not significantly affected by the selected factors, demonstrating the robustness of the procedure. However, the use of different HDMS-beta-CD batches seemed to affect both types of responses necessitating to introduce a warning in the procedure. Since the experiments of the Plackett-Burman design can be assimilated to laboratories in an interlaboratory study, uncertainty can be evaluated using the robustness test data. The robustness test was set-up in such a way that the required variances could be estimated. [less ▲]

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See detailTotal Error-Based Criterion for Analytical Method Transfer Experiments
Rozet, Eric ULg; Dewe, W.; Boulanger, Bruno ULg et al

Conference (2007)

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See detailEvaluation of Analytical Method Transfer on a Risk Based Methodology using Total Error
Rozet, Eric ULg; Dewe, W.; Govaerts, B. et al

Conference (2007)

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See detailPerformances of a multidimensional on-line SPE-LC-ECD method for the determination of three major catecholamines in native human urine: Validation, risk and uncertainty assessments
Rozet, Eric ULg; Morello, Rosa; Lecomte, Frédéric ULg et al

in Journal of Chromatography. B : Analytical Technologies in the Biomedical & Life Sciences (2006), 844(2), 251-260

A novel, multidimensional on-line SPE-LC method with electrochemical detection is described for the fully automated and direct analysis of the catecholamines norepinephrine, epinephrine and dopamine in ... [more ▼]

A novel, multidimensional on-line SPE-LC method with electrochemical detection is described for the fully automated and direct analysis of the catecholamines norepinephrine, epinephrine and dopamine in urine. The integrated extractive clean-up of the raw biofluid is based on a SPE-column packed with restricted access material (RAM) which is modified with the affinity ligand nitrophenylboronic acid. The method was fully validated according to a recent approach based on an accuracy profile. The acceptance limits were set at +/- 15% of the nominal concentration values. The method was found accurate over a concentration range from 15 to 500 mu g/l for norepinephrine, from 5 to 500 mu g/l for epinephrine and from 50 to 500 mu g/l for dopamine. The relative risk for the use of the validated method in routine analysis was also assessed based on this validation strategy. It was found that at most 3.5% of future sample measurements will fall outside the acceptance limits. This demonstrates the high reliability of the analytical method described. Moreover, the measurements uncertainties were deduced from the validation experiments without any additional effort. (c) 2006 Elsevier B.V. All rights reserved. [less ▲]

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See detailThe transfer of a LC-UV method for the determination of fenofibrate and fenofibric acid in Lidoses: Use of total error as decision criterion
Rozet, Eric ULg; Mertens, Bénédicte; Dewé, Walthère ULg et al

in Journal of Pharmaceutical & Biomedical Analysis (2006), 42(1), 64-70

Two new statistical approaches to assess the validity of the transfer of a LC-UV method for the determination of fenofibrate and fenofibric acid were investigated and compared to the conventional ... [more ▼]

Two new statistical approaches to assess the validity of the transfer of a LC-UV method for the determination of fenofibrate and fenofibric acid were investigated and compared to the conventional approaches generally used in this domain. These new approaches, namely the Tolerance Interval and the Risk approaches, are based on the simultaneous evaluation of the systematic (or trueness) and random (or precision) errors of the transfer into a single criterion called total error (or accuracy). The results of the transfer showed that only the total error based approaches fulfilled the objective of an analytical method transfer, i.e. to give guarantees that each future measurement made by the receiving laboratory will be close enough to the true value of the analyte in the sample. Furthermore the Risk approach was the most powerful one and allowed the estimation of the risk to have future measurements out of specification in the receiving laboratory, therefore being a risk management tool. (c) 2006 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 detailComparaison de différentes approches pour accepter un transfert de méthodes analytiques
Rozet, Eric ULg; Dewe, W.; Boulanger, Bruno ULg et al

Scientific conference (2006)

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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 detailApproches par l'erreur totale en transfert analytique
Dewé, Walthère ULg; Boulanger, Bruno ULg; Govaerts, B. et al

Conference (2006)

Detailed reference viewed: 50 (3 ULg)