Jacques Crommen - Academia.edu (original) (raw)

Papers by Jacques Crommen

Research paper thumbnail of Optimization of the LC enantioseparation of chiral pharmaceuticals using cellulose tris(4-chloro-3-methylphenylcarbamate) as chiral selector and polar non-aqueous mobile phases

Journal of Separation Science, 2010

Research paper thumbnail of Comparative enantiomer affinity pattern of β-blockers in aqueous and nonaqueous CE using single-component anionic cyclodextrins

Electrophoresis, Jan 17, 2014

A series of eight chiral β-blocker drugs, acebutolol, atenolol, carazolol, carteolol, carvedilol,... more A series of eight chiral β-blocker drugs, acebutolol, atenolol, carazolol, carteolol, carvedilol, propranolol, sotalol, and talinolol, have been enantioseparated using two single-component anionic β-CD derivatives, namely heptakis (2,3-di-O-methyl-6-sulfo)-β-CD (HDMS-β-CD) and heptakis (2,3-di-O-acetyl-6-sulfo)-β-CD (HDAS-β-CD), in aqueous CE and NACE. The influence of the nature of substituents (methyl or acetyl) in positions 2 and 3 on the CD derivatives and of the electrophoretic medium (water or methanol) on the enantioselectivity and enantiomer affinity pattern (EAP) of these structurally related compounds was systematically studied. All eight β-blockers could be enantioseparated at least partially in the four CE systems, except sotalol with HDMS-β-CD in NACE. In general, lower affinity and enantioselectivity were obtained in the presence of HDMS-β-CD compared to HDAS-β-CD. Reversals of EAPs were observed for all compounds. EAPs toward these two CDs were found to be opposite to...

Research paper thumbnail of Designed combination of chiral selectors for adjustment of enantioseparation selectivity in capillary electrophoresis

Research paper thumbnail of Determination of meprobamate in pharmaceutical dosage forms also containing carbromal by liquid chromatography and indirect photometric detection

Journal of Pharmaceutical and Biomedical Analysis, 1992

In a pharmaceutical form also containing carbromal, meprobamate could not be quantified selective... more In a pharmaceutical form also containing carbromal, meprobamate could not be quantified selectively by classical methods described in pharmacopoeias due to a significant interference from carbromal. Consequently, reversed-phase HPLC methods have been developed to separate the two active ingredients using indirect photometric detection to visualize and determine meprobamate which has very poor chromophoric properties. Different parameters influencing the sensitivity of the indirect response, such as the nature of the highly absorbing compound added to the mobile phase (the marker) as well as the methanol content and the pH of this phase, have been studied. Two chromatographic systems containing benzoic acid or cinnamic acid as the marker, have been optimized and validated. Good linearity and reproducibility have been obtained with both systems but the cinnamic acid method has the advantage that meprobamate and carbromal can be determined simultaneously at 273 nm.

Research paper thumbnail of Simultaneous determination of pirlindole enantiomers and dehydropirlindole by chiral liquid chromatography

Journal of Pharmaceutical and Biomedical Analysis, 1998

Research paper thumbnail of Optimization of micro-HPLC peak focusing for the detection and quantification of low hepcidin concentrations

Journal of Separation Science, 2011

Micro-high-performance liquid chromatography is a miniaturized, economic and ecological chromatog... more Micro-high-performance liquid chromatography is a miniaturized, economic and ecological chromatographic system allowing the use of reduced size chromatographic columns. Coupled with electrospray ionization tandem mass spectrometry, this technique can be used to detect and quantify low concentrations of peptides. In this study, hepcidin was used as the model compound and analysed using octadecylsilica stationary phase by means of a gradient elution mode at a flow rate of 4 μL/min. Several parameters were studied to optimize peak focusing. Using the methodology of experimental design, the mobile-phase gradient conditions and the sample composition were optimized in order to maximize the sensitivity and minimize retention time. Stability of the target peptide in solution was also demonstrated.

Research paper thumbnail of Pre-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

Research paper thumbnail of Enhancement of selectivity and resolution in the enantioseparation of uncharged compounds using mixtures of oppositely charged cyclodextrins in capillary electrophoresis

Research paper thumbnail of Enantiomeric separation of acidic drugs by capillary electrophoresis using a combination of charged and uncharged β-cyclodextrins as chiral selectors

Journal of High Resolution Chromatography, 1996

Research paper thumbnail of Unusual Amino Acids and Monofluoroacetate from Dichapetalum michelsonii (Umutambasha), a Toxic Plant from Rwanda

Planta Medica, 2013

In the course of our investigations on Umutambasha in order to identify its convulsant principles... more In the course of our investigations on Umutambasha in order to identify its convulsant principles, small quantities of monofluoroacetate were observed in stem bark, leaves, and fruits of this plant newly identified as Dichapetalum michelsonii Hauman. Conclusive evidence for a monofluoroacetate presence came from its isolation from the freeze-dried extract of stem bark. Three free unusual amino acids, named N-methyl-α-alanine, N-methyl-β-alanine, and 2,7-diaminooctan-1,8-dioic acid, described for the first time in a plant, and known trigonelline were also isolated from the stem bark of D. michelsonii. Structure elucidations were mainly achieved by spectroscopic methods (1H-NMR, 2D-NMR, MS) and by comparison with authentic references. These unusual amino acids were detected by a fast, reliable TLC analysis in all our batches of Umutambasha, suggesting that they could be used for identification purposes in case of human or livestock intoxications. Finally, EEG recordings and behavioural observations performed in mice suggested that the convulsive patterns produced by Umutambasha are the consequence of monofluoroacetate presence in D. michelsonii.

Research paper thumbnail of High Inorganic Triphosphatase Activities in Bacteria and Mammalian Cells: Identification of the Enzymes Involved

Research paper thumbnail of Factors Influencing Cyclodextrin-Mediated Chiral Separations

Chromatographic Science Series, 2009

Page 106. 4 Factors Influencing Cyclodextrin-Mediated Chiral Separations Anne-Catherine Servais, ... more Page 106. 4 Factors Influencing Cyclodextrin-Mediated Chiral Separations Anne-Catherine Servais, Jacques Crommen, and Marianne Fillet CONTENTS 4.1 Type of CD..... ...

Research paper thumbnail of Ion-pair HPLC of amino acids, dipeptides and alkylamines with UV-detection

Acta pharmaceutica Suecica, 1979

Research paper thumbnail of Mechanistic study on the reversal of enantiomer elution order of amlodipine on selected polysaccharide-based chiral stationary phases in HPLC

The field of enantioseparaition of chiral compounds, especially be the use of high-performance li... more The field of enantioseparaition of chiral compounds, especially be the use of high-performance liquid chromatography (HPLC), has experienced a rapid progress during the last decade. This relates especially to development of new chiral stationary phases, analytical methodologies and technologies for preparative and product scale enantioseparations. In opposite to this, not much progress was achieved in understanding of chiral recognition mechanisms even by most universal chiral HPLC selectors, such as polysaccharide derivatives. Understanding the fine mechanisms of enantiomer elution order (EEO) reversal in HPLC may play a key role in understanding of selector-selectand binding and chiral recognition mechanisms in general. In our recent studies we observed an interesting reversal of enantiomer elution order in HPLC for two chiral analytes with very different chemical structure. In addition, these effects have been observed with polysaccharide-based chiral columns of Lux series having...

Research paper thumbnail of Stratégies analytiques pour la détection de contrefaçons de médicaments pour la dysfonction érectile

Les médicaments de la dysfonction érectile constituent une des classes de médicaments les plus co... more Les médicaments de la dysfonction érectile constituent une des classes de médicaments les plus contrefaites dans les pays industrialisés. Pour lutter contre ce fléau, différentes approches analytiques sont à la disposition des laboratoires de contrôle. Cet article passe en revue les principales approches utilisées et conclut par la présentation d'une stratégie analytique générique pour la gestion des contrefaçons.

Research paper thumbnail of Influence of the background electrolyte composition on analyte response in cyclodextrin mediated nonaqueous capillary electrophoresis-mass spectrometry

Research paper thumbnail of Robustness testing of a chiral NACE method for R-timolol determination in S-timolol maleate and uncertainty assessment from quantitative data

Journal of Pharmaceutical and Biomedical Analysis, 2007

A robustness test of a capillary electrophoresis method for the chiral separation of timolol in n... 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

Research paper thumbnail of Development and validation of a liquid chromatographic method for the stability study of a pharmaceutical formulation containing voriconazole using cellulose tris(4-chloro-3-methylphenylcarbamate) as chiral selector and polar organic mobile phases

Journal of chromatography. A, Jan 10, 2014

The ophthalmic solution of voriconazole, i.e. (2R,3S)-2-(2,4-difluorophenyl)-3-(5-fluoropyrimidin... more The ophthalmic solution of voriconazole, i.e. (2R,3S)-2-(2,4-difluorophenyl)-3-(5-fluoropyrimidin-4-yl)-1-(1H-1,2,4-triazol-1-yl)butan-2-ol, made from an injection formulation which also contains sulfobutylether-β-cyclodextrin sodium salt as an excipient (Vfend), is used for the treatment of fungal keratitis. A liquid chromatographic (LC) method using polar organic mobile phase and cellulose tris(4-chloro-3-methylphenylcarbamate) coated on silica as chiral stationary phase was successfully developed to evaluate the chiral stability of the ophthalmic solution. The percentage of methanol (MeOH) in the mobile phase containing acetonitrile (ACN) as the main solvent significantly influenced the retention and resolution of voriconazole and its enantiomer ((2S,3R)-2-(2,4-difluorophenyl)-3-(5-fluoropyrimidin-4-yl)-1-(1H-1,2,4-triazol-1-yl)butan-2-ol). The optimized mobile phase consisted of ACN/MeOH/diethylamine/trifluoroacetic acid (80/20/0.1/0.1; v/v/v/v). The method was found to be selec...

Research paper thumbnail of Capillary electrophoresis-mass spectrometry, an attractive tool for drug bioanalysis and biomarker discovery

Research paper thumbnail of Use of neutral capillaries for the enantioseparation of N -benzoylated amino acids by capillary electrophoresis with bromobalhimycin as chiral selector

Journal of Separation Science, 2013

In this study, the partial filling technique on both polycationic polymer hexadimethrine bromide ... more In this study, the partial filling technique on both polycationic polymer hexadimethrine bromide (HDB) modified capillary and eCAP neutral capillary were systematically compared in order to enhance the enantioseparation ability of bromobalhimycin as CE additive. The separation conditions, such as pH, the plug length, and the concentration of bromobalhimycin, etc., were optimized in order to obtain satisfactory separations. As expected, for all tested 28 N-benzoylated amino acids, up to five times higher enantioresolutions were obtained on the eCAP neutral capillary compared to that on the polycationic polymer hexadimethrine bromide modified capillary. Moreover, 26 of 28 tested racemic compounds were almost baseline- resolved without observing any interference from the front of the plug of bromobalhimycin. Although the limitation of longer running time on the neutral capillary, it allows the use of higher content of bromobalhimycin in the running buffer without any interference on the detection of analytes when enantioseparations are more difficult to obtain.

Research paper thumbnail of Optimization of the LC enantioseparation of chiral pharmaceuticals using cellulose tris(4-chloro-3-methylphenylcarbamate) as chiral selector and polar non-aqueous mobile phases

Journal of Separation Science, 2010

Research paper thumbnail of Comparative enantiomer affinity pattern of β-blockers in aqueous and nonaqueous CE using single-component anionic cyclodextrins

Electrophoresis, Jan 17, 2014

A series of eight chiral β-blocker drugs, acebutolol, atenolol, carazolol, carteolol, carvedilol,... more A series of eight chiral β-blocker drugs, acebutolol, atenolol, carazolol, carteolol, carvedilol, propranolol, sotalol, and talinolol, have been enantioseparated using two single-component anionic β-CD derivatives, namely heptakis (2,3-di-O-methyl-6-sulfo)-β-CD (HDMS-β-CD) and heptakis (2,3-di-O-acetyl-6-sulfo)-β-CD (HDAS-β-CD), in aqueous CE and NACE. The influence of the nature of substituents (methyl or acetyl) in positions 2 and 3 on the CD derivatives and of the electrophoretic medium (water or methanol) on the enantioselectivity and enantiomer affinity pattern (EAP) of these structurally related compounds was systematically studied. All eight β-blockers could be enantioseparated at least partially in the four CE systems, except sotalol with HDMS-β-CD in NACE. In general, lower affinity and enantioselectivity were obtained in the presence of HDMS-β-CD compared to HDAS-β-CD. Reversals of EAPs were observed for all compounds. EAPs toward these two CDs were found to be opposite to...

Research paper thumbnail of Designed combination of chiral selectors for adjustment of enantioseparation selectivity in capillary electrophoresis

Research paper thumbnail of Determination of meprobamate in pharmaceutical dosage forms also containing carbromal by liquid chromatography and indirect photometric detection

Journal of Pharmaceutical and Biomedical Analysis, 1992

In a pharmaceutical form also containing carbromal, meprobamate could not be quantified selective... more In a pharmaceutical form also containing carbromal, meprobamate could not be quantified selectively by classical methods described in pharmacopoeias due to a significant interference from carbromal. Consequently, reversed-phase HPLC methods have been developed to separate the two active ingredients using indirect photometric detection to visualize and determine meprobamate which has very poor chromophoric properties. Different parameters influencing the sensitivity of the indirect response, such as the nature of the highly absorbing compound added to the mobile phase (the marker) as well as the methanol content and the pH of this phase, have been studied. Two chromatographic systems containing benzoic acid or cinnamic acid as the marker, have been optimized and validated. Good linearity and reproducibility have been obtained with both systems but the cinnamic acid method has the advantage that meprobamate and carbromal can be determined simultaneously at 273 nm.

Research paper thumbnail of Simultaneous determination of pirlindole enantiomers and dehydropirlindole by chiral liquid chromatography

Journal of Pharmaceutical and Biomedical Analysis, 1998

Research paper thumbnail of Optimization of micro-HPLC peak focusing for the detection and quantification of low hepcidin concentrations

Journal of Separation Science, 2011

Micro-high-performance liquid chromatography is a miniaturized, economic and ecological chromatog... more Micro-high-performance liquid chromatography is a miniaturized, economic and ecological chromatographic system allowing the use of reduced size chromatographic columns. Coupled with electrospray ionization tandem mass spectrometry, this technique can be used to detect and quantify low concentrations of peptides. In this study, hepcidin was used as the model compound and analysed using octadecylsilica stationary phase by means of a gradient elution mode at a flow rate of 4 μL/min. Several parameters were studied to optimize peak focusing. Using the methodology of experimental design, the mobile-phase gradient conditions and the sample composition were optimized in order to maximize the sensitivity and minimize retention time. Stability of the target peptide in solution was also demonstrated.

Research paper thumbnail of Pre-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

Research paper thumbnail of Enhancement of selectivity and resolution in the enantioseparation of uncharged compounds using mixtures of oppositely charged cyclodextrins in capillary electrophoresis

Research paper thumbnail of Enantiomeric separation of acidic drugs by capillary electrophoresis using a combination of charged and uncharged β-cyclodextrins as chiral selectors

Journal of High Resolution Chromatography, 1996

Research paper thumbnail of Unusual Amino Acids and Monofluoroacetate from Dichapetalum michelsonii (Umutambasha), a Toxic Plant from Rwanda

Planta Medica, 2013

In the course of our investigations on Umutambasha in order to identify its convulsant principles... more In the course of our investigations on Umutambasha in order to identify its convulsant principles, small quantities of monofluoroacetate were observed in stem bark, leaves, and fruits of this plant newly identified as Dichapetalum michelsonii Hauman. Conclusive evidence for a monofluoroacetate presence came from its isolation from the freeze-dried extract of stem bark. Three free unusual amino acids, named N-methyl-α-alanine, N-methyl-β-alanine, and 2,7-diaminooctan-1,8-dioic acid, described for the first time in a plant, and known trigonelline were also isolated from the stem bark of D. michelsonii. Structure elucidations were mainly achieved by spectroscopic methods (1H-NMR, 2D-NMR, MS) and by comparison with authentic references. These unusual amino acids were detected by a fast, reliable TLC analysis in all our batches of Umutambasha, suggesting that they could be used for identification purposes in case of human or livestock intoxications. Finally, EEG recordings and behavioural observations performed in mice suggested that the convulsive patterns produced by Umutambasha are the consequence of monofluoroacetate presence in D. michelsonii.

Research paper thumbnail of High Inorganic Triphosphatase Activities in Bacteria and Mammalian Cells: Identification of the Enzymes Involved

Research paper thumbnail of Factors Influencing Cyclodextrin-Mediated Chiral Separations

Chromatographic Science Series, 2009

Page 106. 4 Factors Influencing Cyclodextrin-Mediated Chiral Separations Anne-Catherine Servais, ... more Page 106. 4 Factors Influencing Cyclodextrin-Mediated Chiral Separations Anne-Catherine Servais, Jacques Crommen, and Marianne Fillet CONTENTS 4.1 Type of CD..... ...

Research paper thumbnail of Ion-pair HPLC of amino acids, dipeptides and alkylamines with UV-detection

Acta pharmaceutica Suecica, 1979

Research paper thumbnail of Mechanistic study on the reversal of enantiomer elution order of amlodipine on selected polysaccharide-based chiral stationary phases in HPLC

The field of enantioseparaition of chiral compounds, especially be the use of high-performance li... more The field of enantioseparaition of chiral compounds, especially be the use of high-performance liquid chromatography (HPLC), has experienced a rapid progress during the last decade. This relates especially to development of new chiral stationary phases, analytical methodologies and technologies for preparative and product scale enantioseparations. In opposite to this, not much progress was achieved in understanding of chiral recognition mechanisms even by most universal chiral HPLC selectors, such as polysaccharide derivatives. Understanding the fine mechanisms of enantiomer elution order (EEO) reversal in HPLC may play a key role in understanding of selector-selectand binding and chiral recognition mechanisms in general. In our recent studies we observed an interesting reversal of enantiomer elution order in HPLC for two chiral analytes with very different chemical structure. In addition, these effects have been observed with polysaccharide-based chiral columns of Lux series having...

Research paper thumbnail of Stratégies analytiques pour la détection de contrefaçons de médicaments pour la dysfonction érectile

Les médicaments de la dysfonction érectile constituent une des classes de médicaments les plus co... more Les médicaments de la dysfonction érectile constituent une des classes de médicaments les plus contrefaites dans les pays industrialisés. Pour lutter contre ce fléau, différentes approches analytiques sont à la disposition des laboratoires de contrôle. Cet article passe en revue les principales approches utilisées et conclut par la présentation d'une stratégie analytique générique pour la gestion des contrefaçons.

Research paper thumbnail of Influence of the background electrolyte composition on analyte response in cyclodextrin mediated nonaqueous capillary electrophoresis-mass spectrometry

Research paper thumbnail of Robustness testing of a chiral NACE method for R-timolol determination in S-timolol maleate and uncertainty assessment from quantitative data

Journal of Pharmaceutical and Biomedical Analysis, 2007

A robustness test of a capillary electrophoresis method for the chiral separation of timolol in n... 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

Research paper thumbnail of Development and validation of a liquid chromatographic method for the stability study of a pharmaceutical formulation containing voriconazole using cellulose tris(4-chloro-3-methylphenylcarbamate) as chiral selector and polar organic mobile phases

Journal of chromatography. A, Jan 10, 2014

The ophthalmic solution of voriconazole, i.e. (2R,3S)-2-(2,4-difluorophenyl)-3-(5-fluoropyrimidin... more The ophthalmic solution of voriconazole, i.e. (2R,3S)-2-(2,4-difluorophenyl)-3-(5-fluoropyrimidin-4-yl)-1-(1H-1,2,4-triazol-1-yl)butan-2-ol, made from an injection formulation which also contains sulfobutylether-β-cyclodextrin sodium salt as an excipient (Vfend), is used for the treatment of fungal keratitis. A liquid chromatographic (LC) method using polar organic mobile phase and cellulose tris(4-chloro-3-methylphenylcarbamate) coated on silica as chiral stationary phase was successfully developed to evaluate the chiral stability of the ophthalmic solution. The percentage of methanol (MeOH) in the mobile phase containing acetonitrile (ACN) as the main solvent significantly influenced the retention and resolution of voriconazole and its enantiomer ((2S,3R)-2-(2,4-difluorophenyl)-3-(5-fluoropyrimidin-4-yl)-1-(1H-1,2,4-triazol-1-yl)butan-2-ol). The optimized mobile phase consisted of ACN/MeOH/diethylamine/trifluoroacetic acid (80/20/0.1/0.1; v/v/v/v). The method was found to be selec...

Research paper thumbnail of Capillary electrophoresis-mass spectrometry, an attractive tool for drug bioanalysis and biomarker discovery

Research paper thumbnail of Use of neutral capillaries for the enantioseparation of N -benzoylated amino acids by capillary electrophoresis with bromobalhimycin as chiral selector

Journal of Separation Science, 2013

In this study, the partial filling technique on both polycationic polymer hexadimethrine bromide ... more In this study, the partial filling technique on both polycationic polymer hexadimethrine bromide (HDB) modified capillary and eCAP neutral capillary were systematically compared in order to enhance the enantioseparation ability of bromobalhimycin as CE additive. The separation conditions, such as pH, the plug length, and the concentration of bromobalhimycin, etc., were optimized in order to obtain satisfactory separations. As expected, for all tested 28 N-benzoylated amino acids, up to five times higher enantioresolutions were obtained on the eCAP neutral capillary compared to that on the polycationic polymer hexadimethrine bromide modified capillary. Moreover, 26 of 28 tested racemic compounds were almost baseline- resolved without observing any interference from the front of the plug of bromobalhimycin. Although the limitation of longer running time on the neutral capillary, it allows the use of higher content of bromobalhimycin in the running buffer without any interference on the detection of analytes when enantioseparations are more difficult to obtain.