References of "Rozet, Eric"
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See detailApplication of an innovative design space optimization strategy to thedevelopment of LC methods for the simultaneous screening of antibiotics to combat poor quality medicines
Mbinze Kindenge, Jérémie ULg; Dispas, Amandine ULg; Lebrun, Pierre ULg et al

in Journal of Pharmaceutical & Biomedical Analysis (2013), 85

The poor quality of medicines is a crucial problem of public health. Therefore, it is important to haveanalytical tools to attend decisions of the legal authorities while combating this offense. In this ... [more ▼]

The poor quality of medicines is a crucial problem of public health. Therefore, it is important to haveanalytical tools to attend decisions of the legal authorities while combating this offense. In this context,the main objective of this study was to develop generic methods able to trace, screen and determineseveral antibiotics and common associated molecules by mean of liquid chromatographic techniques.For that purpose, an innovative Design Space optimization strategy was applied, targeting 16 antibioticsand 3 beta-lactamase inhibitors. The robustness of the developed method allowed using its use in anenvironment where operational factors such as temperature are not easy to control and eased its trans-fer to Ultra High Performance Liquid Chromatography. To demonstrate its ability to quantify the targetedmolecules, the developed and transferred method was fully validated for two active ingredients com-monly used in association, sulbactam and ceftriaxone, using the accuracy profile as decision tool. Basedon this successful step, the method was then used for the quantitative determination of these two activeingredients in three pharmaceutical brands marketed in the Democratic Republic of Congo. Two out ofthe three pharmaceutical products did not comply with the specifications [less ▲]

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See detailNiveaux du plomb sanguin, du plomb urinaire, de l’acide δ-aminolévulinique et des porphyrines urinaires chez les personnes vivant à Kinshasa, R.D. Congo : une étude pilote de biosurveillance
Mputu Malolo, Corneille-Liévin; Ndelo di Phanzu, Josaphat; Marini Djang'Eing'A, Roland ULg et al

Conference (2013, October 18)

Objectives: Existing naturally in the earth’s crust, Lead is a widely used heavy metal. It is an environment toxicant that may deleteriously affect nervous, hematopoietic, skeletal, renal, endocrine and ... [more ▼]

Objectives: Existing naturally in the earth’s crust, Lead is a widely used heavy metal. It is an environment toxicant that may deleteriously affect nervous, hematopoietic, skeletal, renal, endocrine and reproductive systems. Lead is classified in its inorganic form as possible human carcinogen (group 2A) by IARC. Exposure to lead in the environment continues to be a serious public health problem for all ages. Children are particularly susceptible to lead poisoning. They absorb more lead from their environment and their developing central nervous systems are vulnerable to the toxicant. During the last twenty years, important measures of public health were undertaken in several countries to decrease lead exposure. In the best of our knowledge, this is not the case in D.R. Congo. A study indicated a relatively important lead impregnation of the Kinshasa population (mean 120 μg/L). However, there have been no reported studies in the evaluation of the relationship between urinary lead, urinary δ-aminolevulinic acid (δ-AlaU) and urinary porphyrins and lead blood level in Congolese people. This is the aim of this study targeting at first people living in Kinshasa. Methods: Blood lead and urinary lead levels were measured using inductively coupled plasma mass spectrometry. The Bio-Rad ALA/PBG by Column Test and spectrophotometer method were used to quantify the concentration of δ-Ala in urine. The separation of porphyrins was carried out by HPLC coupled with fluorescence detector. Results: 37% of studied population presented blood lead levels above the 100 μg/L threshold (geometric mean: 133.29 μg/L) with a higher concentration in women than in men (140.30 μg/L vs 130.78 μg/L). 50% of children (0-17 years) presented blood lead levels above the 100 μg/L threshold and 43% of the same population presented blood lead levels above 50 μg/L as accepted nowadays in US. In the adult population, some targeted occupations were found to be associated with high blood lead. A small correlation was observed between urinary lead and blood lead, but no correlation was noticed between δ-AlaU and Porphyrins with lead blood levels. Conclusion: This study confirmed a relatively important Pb impregnation of the Kinshasa population and the existence of a major public health issue requiring corrective actions and the implementation of an appropriate regulation. Also, urinary lead, urinary δ-Ala and urinary porphyrins seems to not to be sensitive markers for monitoring exposure to lead. [less ▲]

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See detailDevelopment and validation of a UHPLC−LTQ−Orbitrap MS method for non-anthocyanin flavonoids quantification in Euterpe oleracea juice
Dias, A.L.; Rozet, Eric ULg; Larondelle, Y. et al

in Analytical and Bioanalytical Chemistry (2013)

Euterpe oleracea fruits have gained much attention because of their phenolic constituents that have shown potential beneficial effects for health. The aim of this work was to identify and quantify major ... [more ▼]

Euterpe oleracea fruits have gained much attention because of their phenolic constituents that have shown potential beneficial effects for health. The aim of this work was to identify and quantify major non-anthocyanin flavonoids in fruit juice by an accurate UHPLC−LTQ−Orbitrap MS method. Fruits were processed to juice, lyophilized and defatted. The residue was then extracted with methanol by sonication and the extraction time optimized giving recovery rates > 90%. Solubilization of dried extract was realized using 40% MeOH which showed the best compromise for MS detection. For the UHPLC quantification, a HSS C18 column (1.8µm) was used with a gradient elution of methanol and water both with 0.1% formic acid. Total error and accuracy profiles were used as validation criteria. Seven compounds and their isomers were successfully separated, including the major non-anthocyanin flavonoids. Calibration in the matrix was found to be more accurate than calibration without matrix. Trueness (< 15% relative bias), repeatability and intermediate precision (<13% RSD), selectivity, response function, linearity, LOD (ranged from 0.04 to 0.81 µg/mL) and LOQ (0.15 - 5.78 µg/mL) for 12 compounds were evaluated and the quantification method validated. Its applicability was demonstrated on real samples from different suppliers. Their qualitative and quantitative profiles were similar and some compounds were for the first time quantified. In addition eriodictyol was identified for the first time in this fruit along with 5 other flavonoids for which we proposed a possible structure. [less ▲]

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See detailDevelopment of a quantitative approach based on surface-enhanced Raman chemical imaging (SER-CI)
De Bleye, Charlotte ULg; Sacre, Pierre-Yves ULg; Dumont, Elodie ULg et al

Conference (2013, October 17)

During the last decade, Raman imaging has taken an important place in the pharmaceutical field [1-2]. It enables to acquire a visual representation of samples while quantifying and identifying molecules ... [more ▼]

During the last decade, Raman imaging has taken an important place in the pharmaceutical field [1-2]. It enables to acquire a visual representation of samples while quantifying and identifying molecules of these samples. However, this technique suffers from a lack of sensitivity and the appearance of fluorescence which can limit its pharmaceutical applications. One way to circumvent these limitations is Surface Enhanced Raman chemical imaging (SER-CI) which presents the advantages of Raman imaging and enables to dramatically increase the Raman scattering of molecules adsorbed or very close to metallic surfaces [3]. The number of publications regarding SER-CI in the pharmaceutical field is very limited probably due to the well-known stability and reproducibility problem of SERS and also due to the difficulty to obtain a homogeneous colloids covering of samples surface before SER-CI analyses. In this context, the possibility to develop a quantitative approach using SER-CI on a pharmaceutical model, presented as paracetamol tablet, was studied. The aim was to develop a SER-CI method enabling to quantify 4-aminophenol (4-AP), which is the main impurity of paracetamol actively research for its toxicity, at a concentration below its limit of specification of 1000 ppm [4]. This pharmaceutical model was first investigated using SERS and a quantitative method enabling to quantify 4-AP from 3 to 15 µg mL-1 was developed and validated [5]. Based on these previous results, the possibility to develop quantitative approach to quantify 4-aminophenol in paracetamol tablet using SER-CI was investigated. Different ways to cover the tablets surface by silver colloids were tested and a homogeneity study was performed in order to improve the repeatability of SER-CI analyses. Afterwards, the SER-CI approach was optimized and different spectral intensity normalizations were tested. Finally, a quantitative approach using SER-CI was developed enabling to quantify 4-AP from 0.025% to 0.2% (w/w) in paracetamol tablets. [less ▲]

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See detailVibrational spectroscopy as PAT compliant tools
Ziemons, Eric ULg; De Bleye, Charlotte ULg; Chavez, Pierre-François ULg et al

Scientific conference (2013, September 10)

In the last decades, intensive research and development dealing with NIR and Raman spectroscopy have taken place in industrial field, espacially in pharmaceutical industry. This enthusiasm can be ... [more ▼]

In the last decades, intensive research and development dealing with NIR and Raman spectroscopy have taken place in industrial field, espacially in pharmaceutical industry. This enthusiasm can be explained by the fact that this technique are regarded as promising and attractive tools in PAT, R&D and Green Chemistry frameworks. Their advantages such as non-invasive, non-destructive, fast data acquisition, minization of sample preparation step and the use of probes in on-line, in-line and at-line are expected to reach the aims of PAT, R&D and Green Chemistry. [less ▲]

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See detailMETHODOLOGIES FOR ESTIMATING REPEATABILITY AND REPRODUCIBILITY VARIANCES IN MULTIVARIATE DATABASES
Rozet, Eric ULg

Master's dissertation (2013)

Due to the huge amount of information available from spectra obtained from the analyses of biological samples using spectroscopic analytical techniques such as NMR or MIR/NIR multivariate analysis such as ... [more ▼]

Due to the huge amount of information available from spectra obtained from the analyses of biological samples using spectroscopic analytical techniques such as NMR or MIR/NIR multivariate analysis such as Principal Component Analysis (PCA) are required to understand the influence of major experimental factors. However, many experiments in these studies have more complexes variability structures than simply comparing several treatments: they may include time effects, biological effects such as diet or hormonal status, and other blocking factors or variability sources: samples stability, age of the individuals, pH of a buffer, days of acquisition, and so on. Analysis of these databases needs to extract from the spectral data matrix the variations linked to a change indicated in the factor of interest. However other sources of variability may impair this objective. This stresses the importance to discover the sources of variability of the spectral data using appropriate methodology. Classically, to analyze such data analysis of variance (ANOVA) or multivariate ANOVA (MANOVA) is used. However direct application of these methodologies to spectrum obtained from structured experimental studies is inappropriate or impossible. More complex data analyses methodologies are required to understand the importance of the various factors implied in the experiments and to provide a measure of their variance components. Three related methodologies have been proposed to achieve this: ANOVA simultaneous component analysis (ASCA), ANOVA-PCA (APCA) and AComDim. The ASCA and APCA methodologies combine first an analysis of variance step (ANOVA) and then a PCA step. The AComDim one adds to the output of the ANOVA-PCA step a multi-block analysis. In addition, an extension of MANOVA is also available called 50-50 MANOVA and Principal variance component analysis (PVCA) has also been proposed. In this work, the usefulness and applicability of these advanced techniques to data analysis of NMR metabolomic spectra and MIR spectra are given to highlight the increase of knowledge gained and the estimation of main sources of variability arising in an experimental setup. In addition another methodology is proposed which combines PCA and Multivariate linear mixed modeling (PCA-MLMM). [less ▲]

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See detailFast method for the simultaneous quantification of toxic polyphenols applied to the selection of genotypes of yam bean (Pachyrhizus sp.) seeds.
Lautié, Emmanuelle; Rozet, Eric ULg; Hubert, Philippe ULg et al

in Talanta (2013), 117

The purpose of the research was to develop and validate a rapid quantification method able to screen many samples of yam bean seeds to determine the content of two toxic polyphenols, namely pachyrrhizine ... [more ▼]

The purpose of the research was to develop and validate a rapid quantification method able to screen many samples of yam bean seeds to determine the content of two toxic polyphenols, namely pachyrrhizine and rotenone. The analytical procedure described is based on the use of an internal standard (dihydrorotenone) and is divided in three steps: microwave assisted extraction, purification by solid phase extraction and assay by ultra high performance liquid chromatography (UHPLC). Each step was included in the validation protocol and the accuracy profiles methodology was used to fully validate the method. The method was fully validated between 0.25mg and 5mg pachyrrhizin per gram of seeds and between 0.58mg/g and 4mg/g for rotenone. More than one hundred samples from different accessions, locations of growth and harvest dates were screened. Pachyrrhizine concentrations ranged from 3.29mg/g to lower than 0.25mg/g while rotenone concentrations ranged from 3.53mg/g to lower than 0.58mg/g. This screening along with principal component analysis (PCA) and discriminant analysis (DA) analyses allowed the selection of the more interesting genotypes in terms of low concentrations of these two toxic polyphenols. [less ▲]

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See detailA new criterion to assess distributional homogeneity in hyperspectral images of solid pharmaceutical dosage forms
Sacre, Pierre-Yves ULg; Lebrun, Pierre ULg; Chavez, Pierre-François ULg et al

Conference (2013, September)

During galenic formulation development, homogeneity of distribution is a critical parameter to check since it may influence activity and safety of the drug. Several techniques exist to assess this ... [more ▼]

During galenic formulation development, homogeneity of distribution is a critical parameter to check since it may influence activity and safety of the drug. Several techniques exist to assess this homogeneity, the most used and recognized being HPLC. However, these techniques are destructive, time consuming and uses a lot of organic solvents. Vibrational spectroscopies are promising green chemistry techniques that may replace HPLC for several analysis tasks thanks of their rapid, non-destructive and non-pollutant characteristics. Raman hyperspectral imaging is a technique of choice for assessing the distributional homogeneity of compounds of interest. Indeed, the combination of both spectroscopic and spatial information provides a detailed knowledge of chemical composition and component distribution. When dealing with hyperspectral imaging, multivariate data analysis is necessary to extract the concentration map of the compound of interest that will be used to assess sample homogeneity. Actually, most authors assess homogeneity using parameters of the histogram of intensities (e.g. mean, skewness and kurtosis). However, this approach does not take into account spatial information and loses the main advantage of imaging. Recently, Rosas et al. proposed a homogeneity index based on the Poole index. However, it necessitates cutting the maps in non-overlapping macropixels and is therefore quickly limited with small maps. To overcome this limitation, we propose a new criterion that combines Continuous Level Moving Blocks and homogeneity curves with a randomization step to assess the distributional homogeneity. This distributional homogeneity index (DHI) enables analysis of hyperspectral maps without apriori knowledge. It has been applied on five pharmaceutical formulations with different blending conditions. The uniformity content values of the API (present at a concentration of 7% w/w) measured by HPLC ranged from RSD: 0.46% to 11.04%. Ten tablets per formulation have been mapped over a region of interest of 4 mm². After extracting pure spectra by MCR-ALS, the concentration maps of the API were computed using classical least squares analysis. DHI have been computed with a hundred simulations for the randomization step for each concentration map. Afterwards, a mean DHI and standard deviation values were computed per formulation. A linear relationship has been observed between the RSD values and the mean DHI. These results enabled us to select the formulation with the best homogeneity. Further experiments are in progress to check whether hyperspectral imaging combined with DHI could be used in routine to assess blending homogeneity of well-known formulations. [less ▲]

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See detailChemical imaging of small molecules from simple to complex matrices: Quantitative approaches based on Surface Enhanced Raman scattering
De Bleye, Charlotte ULg; Sacre, Pierre-Yves ULg; Chavez, Pierre-François ULg et al

Conference (2013, July)

Surface Enhanced Raman scattering (SERS) allows to dramatically exalt the Raman diffusion of molecules absorbed or very closed to rough metallic surfaces while keeping their structural information. SERS ... [more ▼]

Surface Enhanced Raman scattering (SERS) allows to dramatically exalt the Raman diffusion of molecules absorbed or very closed to rough metallic surfaces while keeping their structural information. SERS chemical imaging, presenting a high specificity and sensibility, allows acquiring a visual representation of samples combining spectral and spatial measurements. This technique could become a powerful tool in pharmaceutical and biological analysis enabling to identify and quantify molecules thanks to chemometric evaluation while looking at their distribution or their interactions. In this context, SERS chemical imaging is investigated in detection or quantitative determination of molecules in pharmaceutical and biological matrices. The feasibility of making quantitative measurements using SERS is evaluated on small target molecules models such as 4-aminophenol and lactate. Firstly, a SERS method to quantify 4-aminophenol which is the primary impurity of acetaminophen coming from its degradation during the storage or from its synthesis was developed on a real pharmaceutical formulation. The standard addition method was selected as calibration method in order to take into account the matrix effect coming from the different components of the latter. Despite the well-known stability and repeatability problems of SERS, the method was thoroughly validated by means of accuracy profiles as decision tool. Moreover, this validation methodology allowed to define a first estimation of the real analytical performance of the technique. Secondly, the detection of lactate, which is a critical metabolite implicated in several metabolic disorders, was successfully tested in the physiological concentration in a simple matrix. Preliminary results for the determination of this metabolic biomarker were also very promising allowing to consider more complex matrices. Based on these results, SERS chemical imaging was implemented to detect 4-aminophenol in a pharmaceutical tablet formerly pulverised by a SERS substrate. Through this imaging technique, it was not only possible to detect the presence of the impurity at the limit of specification of 0.1% (w/w) but it was also possible to differentiate tablets comprising different concentrations of the latter. These promising results represent the first step towards quantitative measurements using SERS chemical imaging. [less ▲]

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See detailA New Method for Quality by Design Robust Optimization in Liquid Chromatography
Debrus, Benjamin ULg; Lebrun, Pierre ULg; Rozet, Eric ULg et al

in LC-GC Europe (2013), -(-), -

A new method to optimize liquid chromatography (LC) methods using a Quality by Design (QbD) approach is presented. This method is based on the use of design of experiments (DOE) and independent component ... [more ▼]

A new method to optimize liquid chromatography (LC) methods using a Quality by Design (QbD) approach is presented. This method is based on the use of design of experiments (DOE) and independent component analysis (ICA) to accurately estimate the modelled responses (that is, the retention times at the beginning, the apex, and the end) of each peak, even for coeluted peaks. The modelling of these responses usesmultiple linear regressions, while the propagation of the error affecting the responses and coming from the models is carried out by Monte Carlo simulation. The design space is determined as the region of assay factors where the probability to reach baseline-resolved peaks is higher than the desired level of quality. This method was applied to the optimization of the separation of nine compounds in a mixture, yielding the design space and the demonstration of robustness of the method. Finally, the method was validated. [less ▲]

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See detailInnovative Methodology for the Definition of Design Spaces of Chromatographic Methods
Rozet, Eric ULg; Debrus, B; Lebrun, Pierre ULg et al

Conference (2013, June 06)

As defined by ICH [1] and FDA, Quality by Design (QbD) stands for “a systematic approach to development that begins with predefined objectives and emphasizes product and process understanding and process ... [more ▼]

As defined by ICH [1] and FDA, Quality by Design (QbD) stands for “a systematic approach to development that begins with predefined objectives and emphasizes product and process understanding and process control, based on sound science and quality risk management”. A risk–based QbD–compliant approach is proposed for the robust development of analytical methods. This methodology based on Design of Experiments (DoE) to study the experimental domain models the retention times at the beginning, the apex and the end of each peak corresponding to the compounds of a mixture and uses the separation criterion (S) rather than the resolution (RS) as a Critical Quality Attribute. Stepwise multiple linear regressions are used to create the models. The estimated error is propagated from the modelled responses to the separation criterion (S) using Monte Carlo simulations in order to estimate the predictive distribution of the separation criterion (S) over the whole experimental domain. This allows finding ranges of operating conditions that will guarantee a satisfactory quality of the method in its future use. These ranges define the Design Space (DS) of the method. In chromatographic terms, the chromatograms processed at operating conditions within the DS will assuredly show high quality, with well separated peaks and short run time, for instance. This Design Space can thus be defined as the subspace, necessarily encompassed in the experimental domain (i.e. the knowledge space), within which the probability for the criterion to be higher than an advisedly selected threshold is higher than a minimum quality level. Precisely, the DS is defined as “the multidimensional combination and interaction of input variables (e.g., material attributes) and process parameters that have been demonstrated to provide assurance of quality” [1]. Therefore, this DS defines a region of operating conditions that provide prediction of assurance of quality rather than only quality as obtained with traditional mean response surface optimisation strategies. For instance, in the liquid chromatography there is a great difference in e.g. predicting a resolution (RS) higher than 1.5 vs. predicting that the probability for RS to be higher than 1.5 (i.e. P(RS> 1.5)) is high. The presentation of this global methodology will be illustrated for the robust optimisation and DS definition of several liquid chromatographic methods dedicated to the separation of different mixtures: pharmaceutical formulations, API and impurities/degradation products, plant extracts, separation of enantiomers, … [less ▲]

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See detailDéveloppement de méthodes de quantification en milieu complexe par chromatographie liquide microfluidique couplée à la spectrometrie de masse
Houbart, Virginie ULg; Rozet, Eric ULg; Crommen, Jacques ULg et al

Conference (2013, June)

L’hepcidine est un biomarqueur peptidique dont l’intérêt tant comme outil de diagnostic que de suivi de pathologies est de plus en plus solidement établi. Il existe donc une demande forte d’outils ... [more ▼]

L’hepcidine est un biomarqueur peptidique dont l’intérêt tant comme outil de diagnostic que de suivi de pathologies est de plus en plus solidement établi. Il existe donc une demande forte d’outils sensibles et robustes afin de la doser au sein de milieux biologiques tels que le plasma ou le sérum. Une méthode analytique a été développée à l’aide d’un système chromatographique miniaturisé (nanoLC-chip) couplé à un spectromètre de masse permettant d’assurer un dosage de l’hepcidine à la fois sensible et fiable. Lors du développement de cette méthode, il a été constaté que la composition de l’échantillon avait une influence majeure sur la réponse analytique. Or, l’utilisation de systèmes chromatographiques miniaturisés implique souvent l’injection de volumes proportionnellement très importants par rapport aux dimensions du système, ce qui amplifie encore l’impact de sa composition. C’est pourquoi il est capital d’avoir une bonne compréhension des phénomènes qui ont lieu entre l’injection de l’échantillon dans le système chromatographique et la détection par spectrométrie de masse, et particulièrement lors du développement de méthodes analytiques quantitatives. Dans cette étude, nous avons utilisé la planification expérimentale afin de mieux comprendre le comportement chromatographique des peptides, ainsi que les facteurs qui influencent la sensibilité de la méthode développée. Un mélange de peptides a été sélectionné, varié tant du point de vue du poids moléculaire que du point isoélectrique et de l’hydropathie. Un plan de criblage a permis de délimiter le domaine expérimental ainsi que les facteurs significatifs parmi la composition de la phase mobile (proportion et nature de l’agent de paire d’ions) et de l’échantillon en lui-même (nature de l’agent de paire d’ions et proportion de solvant organique). Ensuite, un plan d’expériences factoriel complet a été mis en œuvre afin d’observer plus finement le rôle de chaque facteur ainsi que les interactions éventuelles qui les lient. Certains facteurs ont montré un effet très marqué tant sur l’intensité de la réponse que sur la rétention. Entre autres, la composition de l’échantillon, facteur parfois négligé lors du développement de méthodes, a démontré son importance capitale, en particulier sur les phénomènes de rétention des peptides. Les données obtenues ont également permis de dégager des conditions optimales d’analyse en termes de rétention et de sensibilité. Enfin, une analyse en composantes principales a également été réalisée sur le grand nombre de données récoltées dans le but de mettre en évidence d’éventuels propriétés physicochimiques des peptides qui pourraient avoir un impact significatif sur les réponses étudiées. [less ▲]

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