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See detailMonitoring of anatabine release by methyl jasmonate elicited BY-2 cells using surface-enhanced Raman scattering
De Bleye, Charlotte ULg; Dumont, Elodie ULg; Dispas, Amandine ULg et al

in Talanta (2016), 160

A new application of surface-enhanced Raman scattering (SERS) in the field of plant material analysis is proposed in this study. The aim was to monitor the release of anatabine by methyl jasmonate (MeJa ... [more ▼]

A new application of surface-enhanced Raman scattering (SERS) in the field of plant material analysis is proposed in this study. The aim was to monitor the release of anatabine by methyl jasmonate (MeJa) elicited Bright Yellow-2 (BY-2) cells. Gold nanoparticles (AuNps) were used as SERS substrate. The first step was to study the SERS activity of anatabine in a complex matrix comprising the culture medium and BY-2 cells. The second step was the calibration. This one was successfully performed directly in the culture medium in order to take into account the matrix effect, by spiking the medium with different concentrations of anatabine, leading to solutions ranging from 250 to 5000 µg L-1. A univariate analysis was performed, the intensity of a band situated at 1028 cm-1, related to anatabine, was plotted against the anatabine concentration. A linear relationship was observed with a R2 of 0.9951. During the monitoring study, after the MeJa elicitation, samples were collected from the culture medium containing BY-2 cells at 0, 24h, 48h, 72h and 96h and were analyzed using SERS. Finally, the amount of anatabine released in the culture medium was determined using the response function, reaching a plateau after 72h of 82 µg of anatabine released / g of fresh weight (FW) MeJa elicited BY-2 cells. [less ▲]

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See detailA simple calibration approach based on film-casting for confocal Raman microscopy to support the development of a Hot-Melt Extrusion process
Netchacovitch, Lauranne ULg; Thiry, Justine ULg; De Bleye, Charlotte ULg et al

in Talanta (2016), 154

When developing a new formulation, the development, calibration and validation steps of analytical methods based on vibrational spectroscopy are time-consuming. For each new formulation, real samples must ... [more ▼]

When developing a new formulation, the development, calibration and validation steps of analytical methods based on vibrational spectroscopy are time-consuming. For each new formulation, real samples must be produced and a “reference method” must be used in order to determine the Active Pharmaceutical Ingredient (API) content of each sample. To circumvent this issue, the paper presents a simple approach based on the film-casting technique used as a calibration tool in the framework of hot-melt extrusion process. Confocal Raman microscopic method was successfully validated for the determination of itraconazole content in film-casting samples. Then, hot-melt extrusion was carried out to produce real samples in order to confront the results obtained with confocal Raman microscopy and Ultra High Performance Liquid Chromatography (UHPLC). The agreement between both methods was demonstrated using a comparison study based on the Bland and Altman’s plot. [less ▲]

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See detailIn situ analysis of lipid oxidation in oilseedbased food products using near-infrared spectroscopy and chemometrics: The sunflower kernel paste (tahini) example
Mureșan; Danthine, Sabine ULg; Mureșan, Andruța Elena et al

in Talanta (2016), 155

A new near-infrared (NIR) spectroscopic method was developed for the analytical measurement of lipid oxidation in sunflower kernel paste (tahini), which was chosen as an example of a complex oilseed-based ... [more ▼]

A new near-infrared (NIR) spectroscopic method was developed for the analytical measurement of lipid oxidation in sunflower kernel paste (tahini), which was chosen as an example of a complex oilseed-based food product. The NIR spectra of sunflower tahini were acquired for the extracted fat phase (EFP) and for the intact sunflower tahini (IST) samples during controlled storage. The best peroxide value (PV) calibration models were considered suitable for quality control (ratio of performance of deviation [RPD] >5). The best PV partial least squares (PLS) model result for EFP (RPD 6.36) was obtained when using standard normal variate (SNV) and the Savitzky-Golay first derivative in the 1140-1184 nm, 1388-1440 nm and 2026-2194 nm regions. In the case of IST spectra, the best PV models (RPD 5.23) were obtained when either multiple scattering correction (MSC) or SNV were followed by the Savitzky-Golay second derivative for the 1148-1180 nm and 2064-2132 nm regions. There were poor correlations between the NIR-predicted values and the reference data of the panisidine value (pAV) for both EFP and IST. Overall, the results obtained showed that NIR spectroscopy is an appropriate analytical tool for monitoring sunflower paste PV in situ. Due to the nonexistence of the extraction step, it demonstrates a unique and substantial advantage over presently known methods. Based on these results it is strongly recommended that, when using NIR PLS models to assess lipid oxidation in situ in similar oilseedbased food products (e.g., sesame tahini, hazelnut and cocoa liquor used for chocolate production, peanut butter, hazelnut, almond, pistachio spreads), suitable calibration sets containing samples of different particle sizes and stored at different temperatures be selected. [less ▲]

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See detailEquiNox2: a new method to measure NADPH oxidase activity and to study effect of inhibitors and their interactions with the enzyme
Derochette, Sandrine ULg; Serteyn, Didier ULg; Mouithys-Mickalad, Ange ULg et al

in Talanta (2015)

Excessive neutrophil stimulation and reactive oxygen species (ROS) production are involved in numerous human or horse pathologies. The modulation of the neutrophil NADPH oxidase (NOX) has a great ... [more ▼]

Excessive neutrophil stimulation and reactive oxygen species (ROS) production are involved in numerous human or horse pathologies. The modulation of the neutrophil NADPH oxidase (NOX) has a great therapeutic potential since this enzyme produces superoxide anion whose most of the other ROS derive. The measurement of NOX activity by cell-free systems is often used to test potential inhibitors of the enzyme. A major drawback of this technique is the possible interferences between inhibitors and the probe, ferricytochrome c, used to measure the activity. We designed the "EquiNox2", a new pharmacological tool, to determine the direct interaction of potential inhibitors with equine phagocytic NOX and their effect on the enzyme activity or assembly. This method consists in binding the membrane fractions of neutrophils containing flavocytochrome b558 or the entire complex, reconstituted in vitro from membrane and cytosolic fractions of PMNs, onto the wells of a microplate followed by incubation with potential inhibitors or drugs. After incubation, the excess of the drug is simply eliminated or washed prior measuring the activity of the reconstituted complex. This latter step avoid the risk of interference between the inhibitor and the revelation solution and can distinguish if inhibitors, strongly bound or not, could interfere with the assembly of the enzymatic complex or with its activity. The EquiNox2 was validated using diphenyliodonium chloride and Gp91ds-tat, two well-known inhibitors largely described for human NADPH oxidase. The present technique was used to study and understand better the effect of curcumin and its water-soluble derivative, NDS27, on the assembly and activity of NOX. We demonstrated that curcumin and NDS27 can strongly bind to the enzyme and prevents its assembly making these molecules good candidates for the treatment of horse or human pathologies implying an excessive activation of neutrophils. [less ▲]

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See detailComprehensive plasma profiling for the characterization of graft-versus-host disease biomarkers
De Bock, Muriel; BEGUIN, Yves ULg; Leprince, Pierre ULg et al

in Talanta (2014), 125

Acute graft-versus-host disease (aGVHD) remains a life-threatening complication of hematopoietic stem cell transplantation (HSCT), limiting its application. To optimize management of aGVHD and reduce ... [more ▼]

Acute graft-versus-host disease (aGVHD) remains a life-threatening complication of hematopoietic stem cell transplantation (HSCT), limiting its application. To optimize management of aGVHD and reduce therapy-related toxicity, early specific markers are needed. The main objective of this study was thus to uncover diagnostic biomarkers comparing plasma protein profiles of patients at the time of acute GVHD diagnosis and of patients undergoing HSCT without aGVHD. Additional analysis of samples taken 15 days before aGVHD diagnosis was also performed to evaluate the potential of the newly discovered biomarkers for early diagnosis. To extract a maximum of information from plasma samples, we used three complementary proteomic approaches, namely 2D-DIGE, SELDI-TOF-MS and 2D-LC-MSE. We identified and confirmed by means of a independent techniques, the differential expression of several proteins indicating significantly increased inflammation response and disturbance in the coagulation cascade. The variation of these proteins was already observed 15 days before GVHD diagnosis, suggesting the potential early detection of the disease before symptoms appearance. Finally, logistic regression analysis determines a composite biomarker panel comprising fibrinogen, fragment of fibrinogen beta chain, SAA, prothrombin fragments, apolipoprotein A1 and hepcidin that optimally discriminated patients with and without GVHD. The area under the receiver operating characteristic curve distinguishing these 2 groups was 0.95. [less ▲]

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See detailAnalysis of collagen preservation in bones recovered in archaeological contexts using NIR Hyperspectral Imaging
Vincke, Damien; Miller, Rebecca ULg; Stassart, Edith ULg et al

in Talanta (2014), 125

The scope of this article is to propose an innovative method based on Near Infrared Hyperspectral Chemical Imaging (NIR-HCI) to rapidly and non-destructively evaluate the relative degree of collagen ... [more ▼]

The scope of this article is to propose an innovative method based on Near Infrared Hyperspectral Chemical Imaging (NIR-HCI) to rapidly and non-destructively evaluate the relative degree of collagen preservation in bones recovered from archaeological contexts. This preliminary study has allowed the evaluation of the potential of the method using bone samples from the Early Upper Palaeolithic, Mesolithic and Neolithic periods at the site of Trou Al'Wesse in Belgium. NIR-HCI, combined with chemometric tools, has identified specific spectral bands characteristic of collagen. A chemometric model has been built using Partial Least Squares Discriminant Analysis (PLS-DA) to identify bones with and without collagen. This enables the evaluation of the degree of collagen preservation and homogeneity in bones within and between different strata, which has direct implications for archaeological applications (e.g., taphonomic analyses, assemblage integrity) and sample selection for sub- sequent analyses requiring collagen. Two archaeological applications are presented: comparison between sub-layers in an Early Upper Palaeolithic unit, and evaluation of the range of variability in collagen preservation within a single Holocene stratum. [less ▲]

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See detailDetermination of 4-aminophenol in a pharmaceutical formulation using Surface Enhanced Raman scattering: from development to method validation
De Bleye, Charlotte ULg; Dumont, Elodie ULg; Rozet, Eric ULg et al

in Talanta (2013), 116

A Surface Enhanced Raman Scattering (SERS) method able to quantify 4-aminophenol in a pharmaceutical formulation based on acetaminophen, also called paracetamol, was developed and, for the first time ... [more ▼]

A Surface Enhanced Raman Scattering (SERS) method able to quantify 4-aminophenol in a pharmaceutical formulation based on acetaminophen, also called paracetamol, was developed and, for the first time, successfully validated. In this context, silver nanoparticles were synthesized according to the method described by Lee-Meisel and used as SERS substrate. The repeatability of the silver colloid synthesis was tested using different methods to characterise the size and the zeta potential of silver nanoparticles freshly synthesized. To optimize the SERS samples preparation, a design of experiments implicating concentrations of citrate-reduced silver nanoparticles and aggregating agent was performed in order to maximize the Raman signal enhancement. Finally, an approach based on tolerance intervals and accuracy profiles was applied in order to thoroughly validate the method in a range of concentrations comprised from 3 to 15 µg mL-1 using normalized band intensities. The standard addition method was selected as method calibration. Therefore, measurements were carried out on 4-aminophenol spiked solutions of the pharmaceutical formulation. Despite the well-known stability and reproducibility problems of SERS, the validation was performed using two operators and 5 batches of nanoparticles, one for each validation day. [less ▲]

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See detailDiscrimination of grassland species and their classification in botanical families by laboratory scale NIR hyperspectral imaging: preliminary results
Dale, Laura ULg; Thewis, André ULg; Boudry, Christelle ULg et al

in Talanta (2013), 116

The objective of this study was to discriminate by a NIR line scan hyperspectral imaging, taxonomic plant families comprised of different grassland species. Plants were collected from semi-natural meadows ... [more ▼]

The objective of this study was to discriminate by a NIR line scan hyperspectral imaging, taxonomic plant families comprised of different grassland species. Plants were collected from semi-natural meadows of the National Apuseni Park, Apuseni Mountains, Gârda area (Romania) according to botanical families. Chemometric tools such as PLS-DA were used to discriminate distinct grassland species, and assign the different species to botanical families. Species within the Poacea family and Other Botanical Families could be distinguished (R2=0.91 and 0.90, respectively) with greater accuracy than those species in the Fabacea family (R2=0.60). A correct classification rate of 99% was obtained in the assignment of the various species to the proper family. Moreover a complete study based on wavelength selection has been performed in order to identify the chemical compound related to each botanical family and therefore to the possible toxicity of the plant. This work could be considered as a first step for the development of a complete procedure for the detection and quantification of possible toxic species in semi-natural meadows used by grazing animals. [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 detailDetermination of inhibitory potency of argatroban toward thrombin by electrophoretically mediated microanalysis
Pochet, Lionel; Servais, Anne-Catherine ULg; Farcas, Elena ULg et al

in Talanta (2013), 116

Developing an EMMA method for enzymatic assay remains a challenge, particularly using UV detection. Indeed, it is necessary to optimize the separation conditions while allowing the enzymatic reaction to ... [more ▼]

Developing an EMMA method for enzymatic assay remains a challenge, particularly using UV detection. Indeed, it is necessary to optimize the separation conditions while allowing the enzymatic reaction to occur within the capillary respecting kinetic constraints and achieving enough sensitivity. In this work, such EMMA methodology was set up to evaluate the inhibitory potency of drugs toward thrombin, a serine protease implicated in the coagulation cascade. To achieve our goal, the separation buffer, the injection sequence, the internal standard and the chromogenic substrate were investigated. The newly developed system was then assessed determining the kinetic Km constant for the selected substrate and compared with the results obtained with a continuous spectrophotometer cell assay. Secondly, the Ki inhibitory constant of the thrombin inhibitor argatroban was determined and found in agreement with the published value. [less ▲]

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See detailAnalysis of the diastereoisomers of alliin by HPLC
DETHIER, Bérénice ULg; Laloux, Morgan ULg; Hanon, Emilien et al

in Talanta (2012), 101

Garlic has been known for its therapeutic effects for centuries and is used worldwide as a functional food. The concentration of the active molecules could be enhanced by a better knowledge of their ... [more ▼]

Garlic has been known for its therapeutic effects for centuries and is used worldwide as a functional food. The concentration of the active molecules could be enhanced by a better knowledge of their biosynthesis. The precursor of these compounds, alliin (a sulfur amino-acid) has been obtained by chemical synthesis. However, this synthesis route also leads to a diastereoisomer as co-product. This work describes the development of an analytical method which allows the separation and quantification of the two diastereoisomers in order to determine in which proportion the natural form can be produced. The HPLC method which was optimized and validated by accuracy profile exploits an original stationary phase consisting of porous graphitic carbon (PGC). Furthermore, the developped method was used to separate the diastereoisomers of methiin, another garlic cysteine sulfoxide, and to analyse and aqueous extract of garlic. The ability to quantify the amount of natural alliin is valuable for further work on garlic molecules and their application for health protection. [less ▲]

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See detailChemometrics and chromatographic fingerprints to discriminate and classify counterfeit medicines containing PDE-5 inhibitors.
Deconinck, Eric; Sacre, Pierre-Yves ULg; Courselle, Patricia et al

in Talanta (2012), 100

Chromatographic fingerprints recorded for a set of genuine and counterfeit samples of Viagra® and Cialis® were evaluated for their use in the detection and classification of counterfeit samples of these ... [more ▼]

Chromatographic fingerprints recorded for a set of genuine and counterfeit samples of Viagra® and Cialis® were evaluated for their use in the detection and classification of counterfeit samples of these groups of medicines. Therefore several exploratory chemometric techniques were applied to reveal structures in the data sets as well as differences among the samples. The focus was on the differentiation between genuine and counterfeit samples and on the differences between the samples of the different classes of counterfeits as defined by the Dutch National Institute for Public Health and the Environment (RIVM). In a second part the revealed differences between the samples were modelled to obtain a predictive model for both the differentiation between genuine and counterfeit samples as well as the classification of the counterfeit samples. The exploratory analysis clearly revealed differences in the data for the genuine and the counterfeit samples and with projection pursuit and hierarchical clustering differences among the different groups of counterfeits could be revealed, especially for the Viagra® data set. For both data sets predictive models were obtained with 100% correct classification rates for the differentiation between genuine and counterfeit medicines and high correct classification rates for the classification in the different classes of counterfeit medicines. For both data sets the best performing models were obtained with Least Square-Support Vector Machines (LS-SVM) and Soft Independent Modelling by Class Analogy (SIMCA). [less ▲]

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See detailSimultaneous measurement of protein-bound 3-chlorotyrosine and homocitrulline by LC-MS/MS after hydrolysis assisted by microwave: application to the study of myeloperoxidase activity during hemodialysis.
Delporte, Cedric; Franck, Thierry ULg; Noyon, Caroline et al

in Talanta (2012), 99

A high degree of uremia is common in patients with end-stage renal disease and has been linked to the development of chronic inflammation and cardiovascular diseases. In conditions where transplantation ... [more ▼]

A high degree of uremia is common in patients with end-stage renal disease and has been linked to the development of chronic inflammation and cardiovascular diseases. In conditions where transplantation is not possible, uremia can be reduced by hemodialysis although the repeated interventions have been implicated in loss of renal function, partially as a result of chronic inflammation and/or oxidative stress processes. In this context, it has been suggested that myeloperoxidase (MPO) can contribute to the oxidative stress during hemodialysis and to the cardiovascular risk. Protein damages due to MPO activity have never been assessed during hemodialysis although two of its reaction products, 3-chlorotyrosine and homocitrulline, are of interest. Indeed, the first one is a specific product of MPO activity and the formation of the second one could be catalyzed by MPO. In order to analyze these products in plasma proteins, a total hydrolysis method followed by liquid chromatography mass spectrometry analysis was developed. Different conditions of hydrolysis were tested and the optimized procedure was assessed for complete hydrolysis and artifactual chlorination. Finally, the method was used for analyzing 3-chlorotyrosine and homocitrulline in plasma proteins during a hemodialysis session in fifteen patients and data were related to measurements of MPO concentration and activity. Both increases in MPO activity and protein-bound 3-chlorotyrosine were observed, highlighting the involvement of MPO in oxidative stress during hemodialysis and further demonstrating the link between hemodialysis and cardiovascular diseases. [less ▲]

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See detailComments on “Uncertainty profiles for the validation of analytical methods” by Saffaj and Ihssane
Rozet, Eric ULg; Ziemons, Eric ULg; Marini Djang'Eing'A, Roland ULg et al

in Talanta (2012), 88

Saffaj et al., recently proposed an uncertainty profile for evaluating the validity of analytical methods using the statistical methodology of γ-confidence β-content tolerance intervals. This profile ... [more ▼]

Saffaj et al., recently proposed an uncertainty profile for evaluating the validity of analytical methods using the statistical methodology of γ-confidence β-content tolerance intervals. This profile assesses the validity of the method by comparing the method measurement uncertainty to a pre defined acceptance limit stating the maximum uncertainty suitable for the method under study. Several years earlier as stated by these authors a SFSTP (Société Française des Sciences et Techniques Pharmaceutique) commission has developed a similar profile called accuracy profile used to assess the validity of analytical methods. This accuracy profile also uses the methodology of statistical tolerance intervals, but β-expectation tolerance intervals. The uncertainty profile of Saffaj et al. and the accuracy profile of the SFSTP commission are both fulfilling the same final purpose. The core question is finally what statistical tolerance interval to use ? The aim of this letter to the editor is to discuss this question and provide arguments that β-expectation tolerance intervals should be prefered to assess the validity of the method as this type of interval give the guarantee that each future results has high probability to fall within pre-specified acceptance limits. [less ▲]

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See detailReply to the responses on the comments on “Uncertainty profiles for the validation of analytical methods” by Saffaj and Ihssane
Rozet, Eric ULg; Ziemons, Eric ULg; Marini Djang'Eing'A, Roland ULg et al

in Talanta (2012), 100

Saffaj et al., recently proposed an uncertainty profile for evaluating the validity of analytical methods using the statistical methodology of γ-confidence β-content tolerance intervals. This profile ... [more ▼]

Saffaj et al., recently proposed an uncertainty profile for evaluating the validity of analytical methods using the statistical methodology of γ-confidence β-content tolerance intervals. This profile assesses the validity of the method by comparing the method measurement uncertainty to a pre defined acceptance limit stating the maximum uncertainty suitable for the method under study. In this letter we comment on the response (T. Saffaj, B. Ihssane, Talanta 94 (2012) 361-362) these authors have made to our previous letter (E. Rozet, E. Ziemons, R.D. Marini, B. Boulanger, Ph. Hubert, Talanta 88 (2012) 769–771). In particular, we demonstrate that β-expectation tolerance intervals are prediction intervals, we show that β-expectation tolerance intervals are highly usefull for assessing analytical methods validation and for estimating measurement uncertainty and finally we show what are the differences and implications for these two topics (validation and uncertainty) when using either the methodology of β-expectation tolerance intervals or the γ-confidence β-content tolerance tolerance interval one. [less ▲]

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See detailNew approach to quantitative analysis of benzo[a]pyrene in food supplements by an immunochemical column test
Beloglazova, Natalia; Goryacheva, Irina; De Saeger, Sarah et al

in Talanta (2011), 85

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See detailPre-study and in-study validation of a SPE-LC-MS-MS method for the determination of 5-S-cysteinyldopa, a melanoma biomarker, in human plasma.
Martin, Gaelle; Mansion, François ULg; Houbart, Virginie ULg et al

in Talanta (2011), 84(2), 280-6

The incidence of malignant melanoma has increased over the past decades, particularly in Caucasian population. This disease presents defavourable prognosis in terms of survey, especially when detection ... [more ▼]

The incidence of malignant melanoma has increased over the past decades, particularly in Caucasian population. This disease presents defavourable prognosis in terms of survey, especially when detection occurs at the metastatic phase. Reliable analytical methods for biomarker determination are thus an interesting tool in pathology detection and follow-up. In this context, a method using SPE-LC-ESI-MS-MS for the determination of 5-S-cysteinyldopa (5-SCD) in human plasma was optimized. The presence of matrix effect was investigated in details while 5-SCD stability was studied according to FDA requirements for the validation of bioanalytical methods. Pre-study and in-study validations of the entire method were then successfully performed by applying the approach based on total measurement error and accuracy profiles over a concentration ranges from 1.6 to 200 ng/ml. Good results with respect to accuracy, trueness and precision were obtained. The maximum risk of observing future measurements falling outside the acceptance limits during routine analysis was also estimated. [less ▲]

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See detailDevelopment and validation by accuracy profile of a method for the analysis of monoterpenes in indoor air by active sampling and thermal desorption-gas chromatography-mass spectrometry
Marlet, Christelle ULg; Lognay, Georges ULg

in Talanta (2010), 82(4), 1230-1239

The technique of thermal desorption (TD)-GC/MS was evaluated for the measurement of monoterpenes in indoor air. The validation strategy was intentionally oriented towards routine use and the reliability ... [more ▼]

The technique of thermal desorption (TD)-GC/MS was evaluated for the measurement of monoterpenes in indoor air. The validation strategy was intentionally oriented towards routine use and the reliability of the method rather than extreme performance. For this reason, validation by accuracy profile was chosen. The accuracy profile procedure, which is based on the concept of total error (bias + standard deviation), guarantees that a known proportion of future results obtained with the method will be within acceptance limits. For all the compounds tested in the present study, α-pinene, α-terpineol, β-pinene, d-limonene, Δ3-carene, camphene, 1,8-cineole, p-cymene, linalool, but not in the case of carvone, the accuracy profile procedure established that at least 95% of the future results obtained would be within the ±15% acceptance limits of the validated method over the whole defined concentration range. Other parameters, such as selectivity, recovery, repeatability, stability of the molecules of interest and the effect of temperature, were also determined. The performance of the described method was finally evaluated by the analysis of indoor air from new timber frame constructions. [less ▲]

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See detailDevelopment and validation of a quantitative method for the selective determination of tin species in tin octoate by differential pulse polarography
Hubert, Cédric ULg; Ziemons, Eric ULg; Rozet, Eric ULg et al

in Talanta (2010), 80(3), 1413-1420

Tin octoate is used as a catalyst in the synthesis of polydimethylsiloxane (PDMS), a room temperature vulcanizing (RTV) silicone rubber. This rubber is largely used in the medical field due to its great ... [more ▼]

Tin octoate is used as a catalyst in the synthesis of polydimethylsiloxane (PDMS), a room temperature vulcanizing (RTV) silicone rubber. This rubber is largely used in the medical field due to its great biocompatibility. In this framework, a high-speed and costless analytical method for the determination of stannic ions, Sn(IV), in the presence of stannous ions, Sn(II), has been developed. The separation of these two ions was carried out using differential pulse polarography (DPP). For this purpose, the tin species contents in the catalyst is quantitatively extracted under inert condition to avoid any changes in the ratio Sn(IV)/Sn(II). Polarography showed well-shaped oxidation and reduction peaks respectively at −650 and −860 mV for stannous ions. The peak of the stannic ion was well separated and appeared at −1210 mV. Many parameters such as extraction process, extraction time, pH, chelating agents and polarographic conditions were optimized. We have also demonstrated that no oxidation of the stannous ions occurred during the sample preparation. The dosing range considered in this study extends between 10 and 40 μg/mL, corresponding to 6.8% and 27.2% of the degradation product (Sn(IV)) in the catalyst, regarding to the sampling. Finally this method was successfully validated using the total error concept. [less ▲]

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