References of "Crommen, Jacques"
     in
Bookmark and Share    
Full Text
Peer Reviewed
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 ▲]

Detailed reference viewed: 75 (4 ULg)
Full Text
Peer Reviewed
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 ▲]

Detailed reference viewed: 94 (26 ULg)
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)

Detailed reference viewed: 31 (8 ULg)
Full Text
Peer Reviewed
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 ▲]

Detailed reference viewed: 53 (7 ULg)
Full Text
Peer Reviewed
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 ▲]

Detailed reference viewed: 153 (10 ULg)
Full Text
Peer Reviewed
See detailEnantiomeric separation of acidic compounds using single-isomer amino cyclodextrin derivatives in nonaqueous capillary electrophoresis
Fradi, Inès; Servais, Anne-Catherine ULg; Pedrini, Matteo et al

in Electrophoresis (2006), 27(17), 3434-3442

The enantiomeric separation of a series of acidic pharmaceuticals (mostly nonsteroidal anti-inflammatory drugs) has been investigated in NACE systems using single-isomer amino beta-CD derivatives. The ... [more ▼]

The enantiomeric separation of a series of acidic pharmaceuticals (mostly nonsteroidal anti-inflammatory drugs) has been investigated in NACE systems using single-isomer amino beta-CD derivatives. The first part of this study consisted of the selection of the basic experimental conditions to separate efficiently the enantiomers of acidic drugs. Several parameters, such as the nature of the ionic BGE components, were studied and a methanolic solution of ammonium acetate containing the cationic CD was selected as BGE. A D-optimal design with 20 experimental points was then applied and the nature and concentration of the CD were found to have a significant effect on the enantiomeric resolution for all studied compounds. Resolution (R(s)) values were always higher with 6-monodeoxy-6-mono(3-hydroxy)propylamino-beta-CD (PA-beta-CD) compared to those obtained with 6-monodeoxy-6-mono(2-hydroxy)propylamino-beta-CD (IPA-beta-CD). However, the latter led to shorter migration times. Generic NACE conditions were then selected by means of the multivariate approach in order to obtain the highest R(s) values in a minimum amount of time. Finally, dependence of separation selectivity, resolution, as well as mobility difference on chiral selector concentration was discussed and binding constants with PA-beta-CD were estimated for the two enantiomers of one of the model compounds, suprofen in these NACE systems. [less ▲]

Detailed reference viewed: 27 (5 ULg)
Full Text
Peer Reviewed
See detailCapillary electrophoresis-mass spectrometry, an attractive tool for drug bioanalysis and biomarker discovery
Servais, Anne-Catherine ULg; Crommen, Jacques ULg; Fillet, Marianne ULg

in Electrophoresis (2006), 27(13), 2616-2629

The coupling of CE with MS detection, a relatively recent hyphenated technique, has gained increasing respect in the field of bioanalytical applications over the past few years. The first part of this ... [more ▼]

The coupling of CE with MS detection, a relatively recent hyphenated technique, has gained increasing respect in the field of bioanalytical applications over the past few years. The first part of this review presents CE-MS applications dealing with drug bioanalysis, including forensic analysis and metabolism studies. Practical considerations to achieve a robust and sensitive CE-MS coupling are also presented. It is indeed essential to strictly control some critical electrospray parameters, such as the sheath liquid composition and flow rate, the nebulizing gas pressure as well as the capillary outlet position. The second part of the review critically describes the applications of CE coupled on-line to MS for the identification of biomarkers in body fluids for diagnostic purposes. Since the sample preparation procedures strongly differ according to the intended use (drug bioanalysis or biomarker discovery), they are discussed separately, taking into account the particular properties of plasma and urine matrices. [less ▲]

Detailed reference viewed: 57 (4 ULg)
Full Text
Peer Reviewed
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 ▲]

Detailed reference viewed: 38 (4 ULg)
Full Text
Peer Reviewed
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 ▲]

Detailed reference viewed: 128 (33 ULg)
Full Text
Peer Reviewed
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 ▲]

Detailed reference viewed: 77 (12 ULg)