Extra virgin olive oil (EVOO) prices reached record levels in 2023, due to the decline in global ... more Extra virgin olive oil (EVOO) prices reached record levels in 2023, due to the decline in global production, mainly linked to drought in the Mediterranean. Without effective controls, the already widespread fraud in this sector will irrevocably worsen. However, the reliability of the current standard method (CSM) for controlling the authenticity of EVOO has been questioned. Besides, authors have recently called for the replacement of certain steps to reduce analysis time and solvent consumption. In fact, CSM based on HPLC-RID analysis of triacylglycerols (TAGs) and GC analysis of fatty acid methyl esters (FAMEs) is tedious and very time consuming. Here, we optimized and validated a UHPLC-APCI-MS/MS method capable of unambiguously identifying 33 TAGs in EVOO in less than 6 min. The limit of detection calculated for the available TAG standards is between 0.3 and 2.5 ng/ml (0.02 ng-0.13 ng of injected quantity). The linearity of the method in real samples is satisfactory (r 2 > 0.99, n = 6) for 27 TAGs with an average area greater than 0.04 %. In real samples, the between-run precision (RSD %) for 29 TAGs with mean area greater than 0.02% does not exceed 11.6%, provided that the injected amount is equal to or greater than 4 μg of EVOO sample. The application of this method to eleven EVOO samples, including a control sample from the International Olive Council, and the processing of the data with a PCA model allow their fine discrimination according to their TAG profiles. In addition to eliminating the GC step of FAME analysis, the high productivity of the proposed method significantly reduces the cost of this essential control step compared to CSM.
Journal of Chemical and Pharmaceutical Research, 2016, 8(3):640-645Journal of Chemical and Pharmaceutical Research, 2016
In this work, we performed a detailed theoretical structural and energetic study of the majority ... more In this work, we performed a detailed theoretical structural and energetic study of the majority triacylglycerols (TAGs) contained in olive oil, their trans isomers and the fatty acids composing them in order to better understand the chromatographic analysis. The geometries of all the studied structures, their relative equilibrium energies and their harmonic frequencies were determined. We carried out energy calculations by DFT method (B3LYP/6-31+G(d)) for fatty acids. We conducted semi empirical calculations (AM1) for larger triacylglycerol molecules. We showed that trans fatty acids are more stable than cis ones. We also showed that triacylglycerols may exist in two possible shapes. For the TAGs that contain the same number of atoms, we compared the relative equilibrium energies and we showed that when the degree of unsaturation increases, the triacylglycerol becomes less stable. The structural and energetic properties obtained in our work are a first step to understand the HPLC phenomenon because they enable us to determine all the needed theoretical parameters to correlate with the retention time of TAGs in HPLC.
This study reports the impact of thermal pretreatment between 400 and 1100 • C on superficially p... more This study reports the impact of thermal pretreatment between 400 and 1100 • C on superficially porous silica particles (e.g. core-shell, fused-core; here abbreviated as SPP silica). The different thermally pretreated SPP silica (400 • C, 900 • C and 1100 • C) were chemically bonded with an octadecyl chain under microwave irradiation. The bare SPP silica, thermally untreated and pretreated, as well as the chemically bonded phases (CBPs) were fully characterized by elemental analysis, diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), and solid state cross polarization magic angle spinning (CP-MAS) 29 Si NMR. The chromatographic properties of the overall set of C 18-thermally pretreated SPP silica stationary phases were determined using the Tanaka test. Complementary, the simplified Veuthey test was used to deeply study the silanol activity, considering a set of 7 basic solutes with various physicochemical properties. Both tests were also performed on different commercial SPP silica columns and different types of bonding chemistry (C18, Phenyl-hexyl, RP-amide, C30, aQ). Multivariate data analyses (hierarchical cluster analysis and principal component analysis) were carried out to define groups of stationary phases with similar chromatographic properties and situate them in relation to those commercially available. These different C 18-thermally pretreated SPP silicas represented a wide range of stationary phases as they were spread out along the score plot. Moreover, this study highlighted that the thermal pretreatment improved the chemical stability of the SPP silica compare to untreated SPP silica and untreated porous silica. Consequently, higher thermal pretreatment can be applied (up to 900 • C) before functionalization without destruction of the silica matrix. Indeed, a significantly lower dissolution of the thermally pretreated SPP silica under aggressive conditions could allow the use of the corresponding functionalized stationary phases at high temperature (60 • C) with good lifetime of the columns.
This study reports the impact of thermal pretreatment between 400 and 1100 • C on superficially p... more This study reports the impact of thermal pretreatment between 400 and 1100 • C on superficially porous silica particles (e.g. core-shell, fused-core; here abbreviated as SPP silica). The different thermally pretreated SPP silica (400 • C, 900 • C and 1100 • C) were chemically bonded with an octadecyl chain under microwave irradiation. The bare SPP silica, thermally untreated and pretreated, as well as the chemically bonded phases (CBPs) were fully characterized by elemental analysis, diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), and solid state cross polarization magic angle spinning (CP-MAS) 29 Si NMR. The chromatographic properties of the overall set of C 18-thermally pretreated SPP silica stationary phases were determined using the Tanaka test. Complementary, the simplified Veuthey test was used to deeply study the silanol activity, considering a set of 7 basic solutes with various physicochemical properties. Both tests were also performed on different commercial SPP silica columns and different types of bonding chemistry (C18, Phenyl-hexyl, RP-amide, C30, aQ). Multivariate data analyses (hierarchical cluster analysis and principal component analysis) were carried out to define groups of stationary phases with similar chromatographic properties and situate them in relation to those commercially available. These different C 18-thermally pretreated SPP silicas represented a wide range of stationary phases as they were spread out along the score plot. Moreover, this study highlighted that the thermal pretreatment improved the chemical stability of the SPP silica compare to untreated SPP silica and untreated porous silica. Consequently, higher thermal pretreatment can be applied (up to 900 • C) before functionalization without destruction of the silica matrix. Indeed, a significantly lower dissolution of the thermally pretreated SPP silica under aggressive conditions could allow the use of the corresponding functionalized stationary phases at high temperature (60 • C) with good lifetime of the columns.
Quatre echantillons de materiaux d'inclusion, de couleur noire, ont ete preleves sur des dall... more Quatre echantillons de materiaux d'inclusion, de couleur noire, ont ete preleves sur des dalles epigraphiques datees de differentes epoques (entre l'epoque medievale et le XVIII eme siecle), dans trois eglises de la region parisienne. Leur analyse par chromatographie en phase gazeuse couplee a la spectrometrie de masse (CPG-SM), apres methanolyse acide et silylation, a permis d'etablir des analogies entre ces quatre prelevements: tous contiennent de la poix obtenue par chauffage direct, plus ou moins important, d'un bois de conifere. Par contre, cette poix est soit pratiquement seule, soit additionnee d'un corps gras (huile ou graisse) ou d'une cire d'abeille. Ces resultats experimentaux sont importants en vue de la restauration des dalles epigraphiques mais egalement pour la connaissance de l'histoire des techniques.
explanation text for Advion Interchim scientific publication, 2023
Six characterization criteria were selected: - 4 of them correspond to the selectivities of the T... more Six characterization criteria were selected: - 4 of them correspond to the selectivities of the Tanaka test: (alpha sté), (alpha pol), (alpha acidic ion exch), (alpha total ion exch). - The fifth, deduced from the Tanaka test, is the hydrophobic potential HP of the stationary phase ; HP measures its resolutive potential, without taking into account the efficiency. - The sixth, is the symmetry parameter, introduced to evaluate in a single value the behavior of the stationary phase against the basic solutes. It compares the average asymmetry factor of the 7 probes of the modified Veuthey test to 1.00. Each criterion was then normalized between 0 and 1 respectively from the lowest and highest values obtained experimentally on the total corpus of phases. Each of the six standardized criteria of a phase was then compared to the same criterion of another phase by calculating their Euclidean distance difference. The closer this value is to zero, the more the two phases compared behave identically with respect to the criterion considered. - The total of the six values of relative proximity dji of any stationary phase j of the corpus with respect to any other phase i of the corpus taken as a reference is then calculated: dji. All of the remaining 112 phases are then ranked in ascending order of dij. In this classification any stationary phase can be taken as a reference. There are therefore 112 different proximity ranking scales allowing the comparison of stationary phases with each other. In summary, the ordered proximity classification of any stationary phase j with respect to any stationary phase i taken as a reference is obtained by ordering the 112 values of dji corresponding to the pair ij of chosen stationary phases. In this classification two stationary phases j and k having respective values dji and dki equal or very close will be a priori candidates to have identical separative properties. BUT using such a proximity ranking is not enough, The standardized criteria of each phase were then reported on a 4-dimensional radar plot (ste), (pol), (acidic ion exch), HP) to which we added two histograms relating to khyd and d(TF;1) allowing a global and visual comparison of the properties of the stationary phases. The whole of this approach has been computerized and allows us to choose alternative phases
using octadecyldimethyl(dimethylamino)silane. The Tanaka test was used to estimate the chromatogr... more using octadecyldimethyl(dimethylamino)silane. The Tanaka test was used to estimate the chromatographic behavior of the overall set of synthesized bonded stationary phases, and their chromatographic performances were compared with similar columns available on the market. In this article, we used microwave irradiation methods to drastically reduce the reaction time for a comparable grafting rate and equivalent chromatographic performances.
using octadecyldimethyl(dimethylamino)silane. The Tanaka test was used to estimate the chromatogr... more using octadecyldimethyl(dimethylamino)silane. The Tanaka test was used to estimate the chromatographic behavior of the overall set of synthesized bonded stationary phases, and their chromatographic performances were compared with similar columns available on the market. In this article, we used microwave irradiation methods to drastically reduce the reaction time for a comparable grafting rate and equivalent chromatographic performances.
using octadecyldimethyl(dimethylamino)silane. The Tanaka test was used to estimate the chromatogr... more using octadecyldimethyl(dimethylamino)silane. The Tanaka test was used to estimate the chromatographic behavior of the overall set of synthesized bonded stationary phases, and their chromatographic performances were compared with similar columns available on the market. In this article, we used microwave irradiation methods to drastically reduce the reaction time for a comparable grafting rate and equivalent chromatographic performances.
Arabidopsis thaliana was transformed with a Sorghum C 4 PEPC cDNA under the control of the 35S pr... more Arabidopsis thaliana was transformed with a Sorghum C 4 PEPC cDNA under the control of the 35S promoter. Primary transformants were isolated and classified on a seed PEPC activity basis: A lines (two-fold increase) and B lines (four-fold increase). Primary transformants also expressed the C 4 PEPC in leaves (up to a 10-fold increase in activity). In seeds, ectopically expressed PEPC impacted on dry weight and total protein content that were increased by up to 30%. In the stable progeny of A and B lines, the increase in PEPC activity was amplified in seeds; however, a decrease in PEPC content and activity (inversely proportional to seed levels) was observed in maternal tissues (leaves and siliques). This was due to the absence of the exogenous C 4 PEPC and a partial decrease in the endogenous C 3 PEPC forms (mRNA, protein and activity). There was no apparent compensation by a PEPC hyperphosphorylation. In these plants, the anaplerotic pathway flux was altered (notably, a decrease in organic acids and glutamine levels) as judged by 1 H NMR metabolite profiling. Whereas in the corresponding seeds (four-to eight-fold increase in PEPC activity) there was no increase in protein and seed mass, but a moderate decrease in lipid content was observed (compared to control plants). Under normal culture conditions, the transformants (primary and progeny) did not show any apparent growth phenotype or modification in seed production per plant. However, the A and B lines exhibited severe growth defects when salt stressed by LiCl.
Arabidopsis thaliana was transformed with a Sorghum C 4 PEPC cDNA under the control of the 35S pr... more Arabidopsis thaliana was transformed with a Sorghum C 4 PEPC cDNA under the control of the 35S promoter. Primary transformants were isolated and classified on a seed PEPC activity basis: A lines (two-fold increase) and B lines (four-fold increase). Primary transformants also expressed the C 4 PEPC in leaves (up to a 10-fold increase in activity). In seeds, ectopically expressed PEPC impacted on dry weight and total protein content that were increased by up to 30%. In the stable progeny of A and B lines, the increase in PEPC activity was amplified in seeds; however, a decrease in PEPC content and activity (inversely proportional to seed levels) was observed in maternal tissues (leaves and siliques). This was due to the absence of the exogenous C 4 PEPC and a partial decrease in the endogenous C 3 PEPC forms (mRNA, protein and activity). There was no apparent compensation by a PEPC hyperphosphorylation. In these plants, the anaplerotic pathway flux was altered (notably, a decrease in organic acids and glutamine levels) as judged by 1 H NMR metabolite profiling. Whereas in the corresponding seeds (four-to eight-fold increase in PEPC activity) there was no increase in protein and seed mass, but a moderate decrease in lipid content was observed (compared to control plants). Under normal culture conditions, the transformants (primary and progeny) did not show any apparent growth phenotype or modification in seed production per plant. However, the A and B lines exhibited severe growth defects when salt stressed by LiCl.
Arabidopsis thaliana was transformed with a Sorghum C 4 PEPC cDNA under the control of the 35S pr... more Arabidopsis thaliana was transformed with a Sorghum C 4 PEPC cDNA under the control of the 35S promoter. Primary transformants were isolated and classified on a seed PEPC activity basis: A lines (two-fold increase) and B lines (four-fold increase). Primary transformants also expressed the C 4 PEPC in leaves (up to a 10-fold increase in activity). In seeds, ectopically expressed PEPC impacted on dry weight and total protein content that were increased by up to 30%. In the stable progeny of A and B lines, the increase in PEPC activity was amplified in seeds; however, a decrease in PEPC content and activity (inversely proportional to seed levels) was observed in maternal tissues (leaves and siliques). This was due to the absence of the exogenous C 4 PEPC and a partial decrease in the endogenous C 3 PEPC forms (mRNA, protein and activity). There was no apparent compensation by a PEPC hyperphosphorylation. In these plants, the anaplerotic pathway flux was altered (notably, a decrease in organic acids and glutamine levels) as judged by 1 H NMR metabolite profiling. Whereas in the corresponding seeds (four-to eight-fold increase in PEPC activity) there was no increase in protein and seed mass, but a moderate decrease in lipid content was observed (compared to control plants). Under normal culture conditions, the transformants (primary and progeny) did not show any apparent growth phenotype or modification in seed production per plant. However, the A and B lines exhibited severe growth defects when salt stressed by LiCl.
Arabidopsis thaliana was transformed with a Sorghum C 4 PEPC cDNA under the control of the 35S pr... more Arabidopsis thaliana was transformed with a Sorghum C 4 PEPC cDNA under the control of the 35S promoter. Primary transformants were isolated and classified on a seed PEPC activity basis: A lines (two-fold increase) and B lines (four-fold increase). Primary transformants also expressed the C 4 PEPC in leaves (up to a 10-fold increase in activity). In seeds, ectopically expressed PEPC impacted on dry weight and total protein content that were increased by up to 30%. In the stable progeny of A and B lines, the increase in PEPC activity was amplified in seeds; however, a decrease in PEPC content and activity (inversely proportional to seed levels) was observed in maternal tissues (leaves and siliques). This was due to the absence of the exogenous C 4 PEPC and a partial decrease in the endogenous C 3 PEPC forms (mRNA, protein and activity). There was no apparent compensation by a PEPC hyperphosphorylation. In these plants, the anaplerotic pathway flux was altered (notably, a decrease in organic acids and glutamine levels) as judged by 1 H NMR metabolite profiling. Whereas in the corresponding seeds (four-to eight-fold increase in PEPC activity) there was no increase in protein and seed mass, but a moderate decrease in lipid content was observed (compared to control plants). Under normal culture conditions, the transformants (primary and progeny) did not show any apparent growth phenotype or modification in seed production per plant. However, the A and B lines exhibited severe growth defects when salt stressed by LiCl.
Extra virgin olive oil (EVOO) prices reached record levels in 2023, due to the decline in global ... more Extra virgin olive oil (EVOO) prices reached record levels in 2023, due to the decline in global production, mainly linked to drought in the Mediterranean. Without effective controls, the already widespread fraud in this sector will irrevocably worsen. However, the reliability of the current standard method (CSM) for controlling the authenticity of EVOO has been questioned. Besides, authors have recently called for the replacement of certain steps to reduce analysis time and solvent consumption. In fact, CSM based on HPLC-RID analysis of triacylglycerols (TAGs) and GC analysis of fatty acid methyl esters (FAMEs) is tedious and very time consuming. Here, we optimized and validated a UHPLC-APCI-MS/MS method capable of unambiguously identifying 33 TAGs in EVOO in less than 6 min. The limit of detection calculated for the available TAG standards is between 0.3 and 2.5 ng/ml (0.02 ng-0.13 ng of injected quantity). The linearity of the method in real samples is satisfactory (r 2 > 0.99, n = 6) for 27 TAGs with an average area greater than 0.04 %. In real samples, the between-run precision (RSD %) for 29 TAGs with mean area greater than 0.02% does not exceed 11.6%, provided that the injected amount is equal to or greater than 4 μg of EVOO sample. The application of this method to eleven EVOO samples, including a control sample from the International Olive Council, and the processing of the data with a PCA model allow their fine discrimination according to their TAG profiles. In addition to eliminating the GC step of FAME analysis, the high productivity of the proposed method significantly reduces the cost of this essential control step compared to CSM.
Journal of Chemical and Pharmaceutical Research, 2016, 8(3):640-645Journal of Chemical and Pharmaceutical Research, 2016
In this work, we performed a detailed theoretical structural and energetic study of the majority ... more In this work, we performed a detailed theoretical structural and energetic study of the majority triacylglycerols (TAGs) contained in olive oil, their trans isomers and the fatty acids composing them in order to better understand the chromatographic analysis. The geometries of all the studied structures, their relative equilibrium energies and their harmonic frequencies were determined. We carried out energy calculations by DFT method (B3LYP/6-31+G(d)) for fatty acids. We conducted semi empirical calculations (AM1) for larger triacylglycerol molecules. We showed that trans fatty acids are more stable than cis ones. We also showed that triacylglycerols may exist in two possible shapes. For the TAGs that contain the same number of atoms, we compared the relative equilibrium energies and we showed that when the degree of unsaturation increases, the triacylglycerol becomes less stable. The structural and energetic properties obtained in our work are a first step to understand the HPLC phenomenon because they enable us to determine all the needed theoretical parameters to correlate with the retention time of TAGs in HPLC.
This study reports the impact of thermal pretreatment between 400 and 1100 • C on superficially p... more This study reports the impact of thermal pretreatment between 400 and 1100 • C on superficially porous silica particles (e.g. core-shell, fused-core; here abbreviated as SPP silica). The different thermally pretreated SPP silica (400 • C, 900 • C and 1100 • C) were chemically bonded with an octadecyl chain under microwave irradiation. The bare SPP silica, thermally untreated and pretreated, as well as the chemically bonded phases (CBPs) were fully characterized by elemental analysis, diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), and solid state cross polarization magic angle spinning (CP-MAS) 29 Si NMR. The chromatographic properties of the overall set of C 18-thermally pretreated SPP silica stationary phases were determined using the Tanaka test. Complementary, the simplified Veuthey test was used to deeply study the silanol activity, considering a set of 7 basic solutes with various physicochemical properties. Both tests were also performed on different commercial SPP silica columns and different types of bonding chemistry (C18, Phenyl-hexyl, RP-amide, C30, aQ). Multivariate data analyses (hierarchical cluster analysis and principal component analysis) were carried out to define groups of stationary phases with similar chromatographic properties and situate them in relation to those commercially available. These different C 18-thermally pretreated SPP silicas represented a wide range of stationary phases as they were spread out along the score plot. Moreover, this study highlighted that the thermal pretreatment improved the chemical stability of the SPP silica compare to untreated SPP silica and untreated porous silica. Consequently, higher thermal pretreatment can be applied (up to 900 • C) before functionalization without destruction of the silica matrix. Indeed, a significantly lower dissolution of the thermally pretreated SPP silica under aggressive conditions could allow the use of the corresponding functionalized stationary phases at high temperature (60 • C) with good lifetime of the columns.
This study reports the impact of thermal pretreatment between 400 and 1100 • C on superficially p... more This study reports the impact of thermal pretreatment between 400 and 1100 • C on superficially porous silica particles (e.g. core-shell, fused-core; here abbreviated as SPP silica). The different thermally pretreated SPP silica (400 • C, 900 • C and 1100 • C) were chemically bonded with an octadecyl chain under microwave irradiation. The bare SPP silica, thermally untreated and pretreated, as well as the chemically bonded phases (CBPs) were fully characterized by elemental analysis, diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), and solid state cross polarization magic angle spinning (CP-MAS) 29 Si NMR. The chromatographic properties of the overall set of C 18-thermally pretreated SPP silica stationary phases were determined using the Tanaka test. Complementary, the simplified Veuthey test was used to deeply study the silanol activity, considering a set of 7 basic solutes with various physicochemical properties. Both tests were also performed on different commercial SPP silica columns and different types of bonding chemistry (C18, Phenyl-hexyl, RP-amide, C30, aQ). Multivariate data analyses (hierarchical cluster analysis and principal component analysis) were carried out to define groups of stationary phases with similar chromatographic properties and situate them in relation to those commercially available. These different C 18-thermally pretreated SPP silicas represented a wide range of stationary phases as they were spread out along the score plot. Moreover, this study highlighted that the thermal pretreatment improved the chemical stability of the SPP silica compare to untreated SPP silica and untreated porous silica. Consequently, higher thermal pretreatment can be applied (up to 900 • C) before functionalization without destruction of the silica matrix. Indeed, a significantly lower dissolution of the thermally pretreated SPP silica under aggressive conditions could allow the use of the corresponding functionalized stationary phases at high temperature (60 • C) with good lifetime of the columns.
Quatre echantillons de materiaux d'inclusion, de couleur noire, ont ete preleves sur des dall... more Quatre echantillons de materiaux d'inclusion, de couleur noire, ont ete preleves sur des dalles epigraphiques datees de differentes epoques (entre l'epoque medievale et le XVIII eme siecle), dans trois eglises de la region parisienne. Leur analyse par chromatographie en phase gazeuse couplee a la spectrometrie de masse (CPG-SM), apres methanolyse acide et silylation, a permis d'etablir des analogies entre ces quatre prelevements: tous contiennent de la poix obtenue par chauffage direct, plus ou moins important, d'un bois de conifere. Par contre, cette poix est soit pratiquement seule, soit additionnee d'un corps gras (huile ou graisse) ou d'une cire d'abeille. Ces resultats experimentaux sont importants en vue de la restauration des dalles epigraphiques mais egalement pour la connaissance de l'histoire des techniques.
explanation text for Advion Interchim scientific publication, 2023
Six characterization criteria were selected: - 4 of them correspond to the selectivities of the T... more Six characterization criteria were selected: - 4 of them correspond to the selectivities of the Tanaka test: (alpha sté), (alpha pol), (alpha acidic ion exch), (alpha total ion exch). - The fifth, deduced from the Tanaka test, is the hydrophobic potential HP of the stationary phase ; HP measures its resolutive potential, without taking into account the efficiency. - The sixth, is the symmetry parameter, introduced to evaluate in a single value the behavior of the stationary phase against the basic solutes. It compares the average asymmetry factor of the 7 probes of the modified Veuthey test to 1.00. Each criterion was then normalized between 0 and 1 respectively from the lowest and highest values obtained experimentally on the total corpus of phases. Each of the six standardized criteria of a phase was then compared to the same criterion of another phase by calculating their Euclidean distance difference. The closer this value is to zero, the more the two phases compared behave identically with respect to the criterion considered. - The total of the six values of relative proximity dji of any stationary phase j of the corpus with respect to any other phase i of the corpus taken as a reference is then calculated: dji. All of the remaining 112 phases are then ranked in ascending order of dij. In this classification any stationary phase can be taken as a reference. There are therefore 112 different proximity ranking scales allowing the comparison of stationary phases with each other. In summary, the ordered proximity classification of any stationary phase j with respect to any stationary phase i taken as a reference is obtained by ordering the 112 values of dji corresponding to the pair ij of chosen stationary phases. In this classification two stationary phases j and k having respective values dji and dki equal or very close will be a priori candidates to have identical separative properties. BUT using such a proximity ranking is not enough, The standardized criteria of each phase were then reported on a 4-dimensional radar plot (ste), (pol), (acidic ion exch), HP) to which we added two histograms relating to khyd and d(TF;1) allowing a global and visual comparison of the properties of the stationary phases. The whole of this approach has been computerized and allows us to choose alternative phases
using octadecyldimethyl(dimethylamino)silane. The Tanaka test was used to estimate the chromatogr... more using octadecyldimethyl(dimethylamino)silane. The Tanaka test was used to estimate the chromatographic behavior of the overall set of synthesized bonded stationary phases, and their chromatographic performances were compared with similar columns available on the market. In this article, we used microwave irradiation methods to drastically reduce the reaction time for a comparable grafting rate and equivalent chromatographic performances.
using octadecyldimethyl(dimethylamino)silane. The Tanaka test was used to estimate the chromatogr... more using octadecyldimethyl(dimethylamino)silane. The Tanaka test was used to estimate the chromatographic behavior of the overall set of synthesized bonded stationary phases, and their chromatographic performances were compared with similar columns available on the market. In this article, we used microwave irradiation methods to drastically reduce the reaction time for a comparable grafting rate and equivalent chromatographic performances.
using octadecyldimethyl(dimethylamino)silane. The Tanaka test was used to estimate the chromatogr... more using octadecyldimethyl(dimethylamino)silane. The Tanaka test was used to estimate the chromatographic behavior of the overall set of synthesized bonded stationary phases, and their chromatographic performances were compared with similar columns available on the market. In this article, we used microwave irradiation methods to drastically reduce the reaction time for a comparable grafting rate and equivalent chromatographic performances.
Arabidopsis thaliana was transformed with a Sorghum C 4 PEPC cDNA under the control of the 35S pr... more Arabidopsis thaliana was transformed with a Sorghum C 4 PEPC cDNA under the control of the 35S promoter. Primary transformants were isolated and classified on a seed PEPC activity basis: A lines (two-fold increase) and B lines (four-fold increase). Primary transformants also expressed the C 4 PEPC in leaves (up to a 10-fold increase in activity). In seeds, ectopically expressed PEPC impacted on dry weight and total protein content that were increased by up to 30%. In the stable progeny of A and B lines, the increase in PEPC activity was amplified in seeds; however, a decrease in PEPC content and activity (inversely proportional to seed levels) was observed in maternal tissues (leaves and siliques). This was due to the absence of the exogenous C 4 PEPC and a partial decrease in the endogenous C 3 PEPC forms (mRNA, protein and activity). There was no apparent compensation by a PEPC hyperphosphorylation. In these plants, the anaplerotic pathway flux was altered (notably, a decrease in organic acids and glutamine levels) as judged by 1 H NMR metabolite profiling. Whereas in the corresponding seeds (four-to eight-fold increase in PEPC activity) there was no increase in protein and seed mass, but a moderate decrease in lipid content was observed (compared to control plants). Under normal culture conditions, the transformants (primary and progeny) did not show any apparent growth phenotype or modification in seed production per plant. However, the A and B lines exhibited severe growth defects when salt stressed by LiCl.
Arabidopsis thaliana was transformed with a Sorghum C 4 PEPC cDNA under the control of the 35S pr... more Arabidopsis thaliana was transformed with a Sorghum C 4 PEPC cDNA under the control of the 35S promoter. Primary transformants were isolated and classified on a seed PEPC activity basis: A lines (two-fold increase) and B lines (four-fold increase). Primary transformants also expressed the C 4 PEPC in leaves (up to a 10-fold increase in activity). In seeds, ectopically expressed PEPC impacted on dry weight and total protein content that were increased by up to 30%. In the stable progeny of A and B lines, the increase in PEPC activity was amplified in seeds; however, a decrease in PEPC content and activity (inversely proportional to seed levels) was observed in maternal tissues (leaves and siliques). This was due to the absence of the exogenous C 4 PEPC and a partial decrease in the endogenous C 3 PEPC forms (mRNA, protein and activity). There was no apparent compensation by a PEPC hyperphosphorylation. In these plants, the anaplerotic pathway flux was altered (notably, a decrease in organic acids and glutamine levels) as judged by 1 H NMR metabolite profiling. Whereas in the corresponding seeds (four-to eight-fold increase in PEPC activity) there was no increase in protein and seed mass, but a moderate decrease in lipid content was observed (compared to control plants). Under normal culture conditions, the transformants (primary and progeny) did not show any apparent growth phenotype or modification in seed production per plant. However, the A and B lines exhibited severe growth defects when salt stressed by LiCl.
Arabidopsis thaliana was transformed with a Sorghum C 4 PEPC cDNA under the control of the 35S pr... more Arabidopsis thaliana was transformed with a Sorghum C 4 PEPC cDNA under the control of the 35S promoter. Primary transformants were isolated and classified on a seed PEPC activity basis: A lines (two-fold increase) and B lines (four-fold increase). Primary transformants also expressed the C 4 PEPC in leaves (up to a 10-fold increase in activity). In seeds, ectopically expressed PEPC impacted on dry weight and total protein content that were increased by up to 30%. In the stable progeny of A and B lines, the increase in PEPC activity was amplified in seeds; however, a decrease in PEPC content and activity (inversely proportional to seed levels) was observed in maternal tissues (leaves and siliques). This was due to the absence of the exogenous C 4 PEPC and a partial decrease in the endogenous C 3 PEPC forms (mRNA, protein and activity). There was no apparent compensation by a PEPC hyperphosphorylation. In these plants, the anaplerotic pathway flux was altered (notably, a decrease in organic acids and glutamine levels) as judged by 1 H NMR metabolite profiling. Whereas in the corresponding seeds (four-to eight-fold increase in PEPC activity) there was no increase in protein and seed mass, but a moderate decrease in lipid content was observed (compared to control plants). Under normal culture conditions, the transformants (primary and progeny) did not show any apparent growth phenotype or modification in seed production per plant. However, the A and B lines exhibited severe growth defects when salt stressed by LiCl.
Arabidopsis thaliana was transformed with a Sorghum C 4 PEPC cDNA under the control of the 35S pr... more Arabidopsis thaliana was transformed with a Sorghum C 4 PEPC cDNA under the control of the 35S promoter. Primary transformants were isolated and classified on a seed PEPC activity basis: A lines (two-fold increase) and B lines (four-fold increase). Primary transformants also expressed the C 4 PEPC in leaves (up to a 10-fold increase in activity). In seeds, ectopically expressed PEPC impacted on dry weight and total protein content that were increased by up to 30%. In the stable progeny of A and B lines, the increase in PEPC activity was amplified in seeds; however, a decrease in PEPC content and activity (inversely proportional to seed levels) was observed in maternal tissues (leaves and siliques). This was due to the absence of the exogenous C 4 PEPC and a partial decrease in the endogenous C 3 PEPC forms (mRNA, protein and activity). There was no apparent compensation by a PEPC hyperphosphorylation. In these plants, the anaplerotic pathway flux was altered (notably, a decrease in organic acids and glutamine levels) as judged by 1 H NMR metabolite profiling. Whereas in the corresponding seeds (four-to eight-fold increase in PEPC activity) there was no increase in protein and seed mass, but a moderate decrease in lipid content was observed (compared to control plants). Under normal culture conditions, the transformants (primary and progeny) did not show any apparent growth phenotype or modification in seed production per plant. However, the A and B lines exhibited severe growth defects when salt stressed by LiCl.
Chromatograms of TAG from 92 oils gained in NARP-ELSD are shown. identification was confirmed by ... more Chromatograms of TAG from 92 oils gained in NARP-ELSD are shown. identification was confirmed by LC-MS. Isomeric C18:3 TAG were well separated. Pseudo quantitative analysis of TAG from 172 oils is reported. Index of occurence of TAG is also reported.
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Papers by Alain Tchapla
Pseudo quantitative analysis of TAG from 172 oils is reported.
Index of occurence of TAG is also reported.