DEVELOPMENT OF GC-MS/MS METHOD WITH PROGRAMMABLE TEMPERATURE VAPORIZATION LARGE VOLUME INJECTION FOR MONITORING OF 17β-ESTRADIOL AND 2-METHOXYESTRADIOL IN PLASMA
20 October 2011, 21:58:47
Publication year: 2011
Source: Analytica Chimica Acta, Available online 20 October 2011
A.K. Tsakalof, D.C. Gkagtzis, G.N. Koukoulis, C.S. Hadjichristodoulou
Monitoring of estradiol and its metabolites in biological samples is essential for the accurate diagnosis of a number of endocrine diseases. In this study, a sensitive, precise and specific GC-MS/MS method for the quantification of 17β-estradiol (17-BE) and its main metabolite, 2-methoxyestradiol (2MEOE), in plasma was developed and validated. Plasma concentrations of these steroids are currently investigated as diagnostic markers for pre-eclampsia, a systematic disorder of pregnancy and a leading cause of maternal and fetal morbidity and mortality worldwide.The method comprised treatment of the plasma sample by protein precipitation and subsequent isolation of steroids by solid phase extraction, derivatization of steroids by trifluoroacetic anhydride and GC-MS/MS analysis of the derivatized steroids. The large volume (10 μL) injection with the assistance of a Programmed Temperature Vaporization (PTV) injector in solvent split mode allowed a substantial increase in the sensitivity of the method.The ion trap MS was operated in optimized Product Ion Scan. By increasing the damping gas flow in the ion trap from the conventional 0.3 mL/min to 2 mL/min, ion fragmentation was reduced and the instrument response was enhanced substantially. As a result, mass spectra with predominant molecular ions were acquired and molecular ions of the steroids of interest were used as precursor ions thus increasing specificity of the method.Under optimized GC-MS/MS conditions in product ion mode, the Limit of Detection (LOD) of the analyzed steroids ranged from 18.4 pg*mLfor 17BE to 5.5 pg*mLfor 2MEOE (S/N = 3). The instrument response was linear in the investigated concentration range from 0.1 to 10 ng*mL-1 with R > 0.99 for 17BE and 2MEOE. The intra-batch accuracy obtained for quality control samples at the concentration levels of 0.1, 1, 3, 7 ng*mL-1 ranged from 94.9 to 109.9% for 17BE and from 99.9 to 104.5% for 2MEOE.
Source: Analytica Chimica Acta, Available online 20 October 2011
A.K. Tsakalof, D.C. Gkagtzis, G.N. Koukoulis, C.S. Hadjichristodoulou
Monitoring of estradiol and its metabolites in biological samples is essential for the accurate diagnosis of a number of endocrine diseases. In this study, a sensitive, precise and specific GC-MS/MS method for the quantification of 17β-estradiol (17-BE) and its main metabolite, 2-methoxyestradiol (2MEOE), in plasma was developed and validated. Plasma concentrations of these steroids are currently investigated as diagnostic markers for pre-eclampsia, a systematic disorder of pregnancy and a leading cause of maternal and fetal morbidity and mortality worldwide.The method comprised treatment of the plasma sample by protein precipitation and subsequent isolation of steroids by solid phase extraction, derivatization of steroids by trifluoroacetic anhydride and GC-MS/MS analysis of the derivatized steroids. The large volume (10 μL) injection with the assistance of a Programmed Temperature Vaporization (PTV) injector in solvent split mode allowed a substantial increase in the sensitivity of the method.The ion trap MS was operated in optimized Product Ion Scan. By increasing the damping gas flow in the ion trap from the conventional 0.3 mL/min to 2 mL/min, ion fragmentation was reduced and the instrument response was enhanced substantially. As a result, mass spectra with predominant molecular ions were acquired and molecular ions of the steroids of interest were used as precursor ions thus increasing specificity of the method.Under optimized GC-MS/MS conditions in product ion mode, the Limit of Detection (LOD) of the analyzed steroids ranged from 18.4 pg*mLfor 17BE to 5.5 pg*mLfor 2MEOE (S/N = 3). The instrument response was linear in the investigated concentration range from 0.1 to 10 ng*mL-1 with R > 0.99 for 17BE and 2MEOE. The intra-batch accuracy obtained for quality control samples at the concentration levels of 0.1, 1, 3, 7 ng*mL-1 ranged from 94.9 to 109.9% for 17BE and from 99.9 to 104.5% for 2MEOE.
Highlights
► GC-MS/MS method for the quantification of 17β-estradiol and 2-methoxyestradiol in plasma. ► Increased sensitivity with Ion Trap operated under increased damping gas flow. ► Straightforward and efficient method for steroids’ isolation from plasma is described. ► LOD 5.5 and 18.4 pg*mL-1 for 2-methoxyestradiol and 17β-estradiol respectively.Molecular criteria for discriminating museum Asian lacquerware from different vegetal origins by pyrolysis gas chromatography/mass spectrometry
20 October 2011, 21:58:47
Publication year: 2011
Source: Analytica Chimica Acta, Available online 19 October 2011
Anne-Solenn Le Hô, Martine Regert, Olivier Marescot, Chloé Duhamel, Juliette Langlois, ...
This paper focuses on the identification of several chemical markers of vegetal species of Oriental lacquers with the aim at providing a methodology consistent with sampling restrictions necessarily applied in the field of cultural heritage. The method proposed is based on rapid and easy single step thermally assisted hydrolysis–methylation (THM) pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) analysis that can be carried out with a minimum amount of matter (typically 10 μg for a sample collected on a museum or an archaeological object).The main contribution of this study is to provide multiple molecular criteria for discriminating the three Asian species used for making lacquers, namelyRhus vernicifluaStokes,Rhus succedaneaandMelanorrhoea usitata. Because these trees grow in specific areas, identifying the species involved in ancient lacquer coatings also provides geobotanical data and fruitful information on the exchange networks and trading routes developed by ancient societies.With this purpose, a systematic study of all pyrolysis products of lacquer coatings was carried out on modern dried lacquer films from authentified provenance. It was demonstrated that the whole pyrolysis products play a significant role in identifying the vegetal species. The chemotaxonomic value of homologous series of alkanes, alkenes and benzene derivatives, rarely explored until now, was assessed. It was shown that the combination of data related to five distinct groups of pyrolytic markers (composition and/or distribution of alkanes, alkenes and benzene, alkenyl-, alkylcatechol and phenol derivatives) provided new strong criteria to establish vegetal origin and provenance of Asian artworks, eventhough they have been largely altered over time.Case studies of archaeological Chinese lacquered artefacts and Japanese Buddhistic altar were thereafter successfully investigated to address informative potential and efficiency of these criteria on ancient and degraded lacquer coatings.
Source: Analytica Chimica Acta, Available online 19 October 2011
Anne-Solenn Le Hô, Martine Regert, Olivier Marescot, Chloé Duhamel, Juliette Langlois, ...
This paper focuses on the identification of several chemical markers of vegetal species of Oriental lacquers with the aim at providing a methodology consistent with sampling restrictions necessarily applied in the field of cultural heritage. The method proposed is based on rapid and easy single step thermally assisted hydrolysis–methylation (THM) pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) analysis that can be carried out with a minimum amount of matter (typically 10 μg for a sample collected on a museum or an archaeological object).The main contribution of this study is to provide multiple molecular criteria for discriminating the three Asian species used for making lacquers, namelyRhus vernicifluaStokes,Rhus succedaneaandMelanorrhoea usitata. Because these trees grow in specific areas, identifying the species involved in ancient lacquer coatings also provides geobotanical data and fruitful information on the exchange networks and trading routes developed by ancient societies.With this purpose, a systematic study of all pyrolysis products of lacquer coatings was carried out on modern dried lacquer films from authentified provenance. It was demonstrated that the whole pyrolysis products play a significant role in identifying the vegetal species. The chemotaxonomic value of homologous series of alkanes, alkenes and benzene derivatives, rarely explored until now, was assessed. It was shown that the combination of data related to five distinct groups of pyrolytic markers (composition and/or distribution of alkanes, alkenes and benzene, alkenyl-, alkylcatechol and phenol derivatives) provided new strong criteria to establish vegetal origin and provenance of Asian artworks, eventhough they have been largely altered over time.Case studies of archaeological Chinese lacquered artefacts and Japanese Buddhistic altar were thereafter successfully investigated to address informative potential and efficiency of these criteria on ancient and degraded lacquer coatings.
Highlights
► chemical geobotanical markers of Asian lacquers to discriminate vegetal species ► conservation of ancient lacquerware relies to a knowledge on their materials ► small specimens have to be extracted from the art works to preserve themCapillary Electrophoretic Studies on Displacement and Proteolytic Cleavage of Surface Bound Oligohistidine Peptide on Quantum Dots
20 October 2011, 21:58:47
Publication year: 2011
Source: Analytica Chimica Acta, Available online 19 October 2011
Jianhao Wang, Jiang Xia
Subtle changes in the chemical structure or the composition of surface bound ligands on quantum dots (QDs) remain difficult to detect. Here we describe a facile setup for fluorescence detection coupled capillary electrophoresis (CE-FL) and its application in monitoring ligand displacement on QDs through metal-affinity driven assembly. We also describe the use of CE-FL to monitor amide bond cleavage by a specific protease, based on Förster resonance energy transfer (FRET) between Cy5 and QDs spaced by a hexahistidine peptide (H6-Cy5). CE-FL allowed separation of unbound QDs and ligand bound QDs and also revealed an ordered assembly of H6-Cy5 on QDs. In a ligand displacement experiment, unlabeled hexahistidine peptide gradually displaced surface bound H6-Cy5 until finally reaching equilibrium. The displacement intermediates were clearly separated on CE-FL. Proteolytic cleavage of surface bound H6-Cy5 by thrombin was monitored by CE-FL through mobility shift, peak broadening, and FRET changes. Enzymatic parameters thus obtained were comparable with those measured by fluorescence spectroscopy.
Source: Analytica Chimica Acta, Available online 19 October 2011
Jianhao Wang, Jiang Xia
Subtle changes in the chemical structure or the composition of surface bound ligands on quantum dots (QDs) remain difficult to detect. Here we describe a facile setup for fluorescence detection coupled capillary electrophoresis (CE-FL) and its application in monitoring ligand displacement on QDs through metal-affinity driven assembly. We also describe the use of CE-FL to monitor amide bond cleavage by a specific protease, based on Förster resonance energy transfer (FRET) between Cy5 and QDs spaced by a hexahistidine peptide (H6-Cy5). CE-FL allowed separation of unbound QDs and ligand bound QDs and also revealed an ordered assembly of H6-Cy5 on QDs. In a ligand displacement experiment, unlabeled hexahistidine peptide gradually displaced surface bound H6-Cy5 until finally reaching equilibrium. The displacement intermediates were clearly separated on CE-FL. Proteolytic cleavage of surface bound H6-Cy5 by thrombin was monitored by CE-FL through mobility shift, peak broadening, and FRET changes. Enzymatic parameters thus obtained were comparable with those measured by fluorescence spectroscopy.
Highlights
► Capillary electrophoresis reveals details in QD-oligohistidine peptide binding; ► An ordered assembly of peptides on QDs was revealed; ► Intermediates of QD-peptide binding were found; ► Detailed displacement kinetics was revealed; ► Proteolysis of surface ligands causes mobility shift and peak broadening in CEProtein Separation by Capillary Gel Electrophoresis: A Review
20 October 2011, 21:58:47
Publication year: 2011
Source: Analytica Chimica Acta, Available online 19 October 2011
Zaifang Zhu, Joann J. Lu, Shaorong Liu
Capillary gel electrophoresis (CGE) has been used for protein separation for more than two decades. Due to the technology advancement, current CGE methods are becoming more and more robust and reliable for protein analysis, and some of the methods have been routinely used for the analysis of protein-based pharmaceuticals and quality controls. In light of this progress, we survey 147 papers related to CGE separations of proteins and present an overview of this technology. We first introduce briefly the early development of CGE. We then review the methodology, in which we specifically describe the matrices, coatings, and detection strategies used in CGE. CGE using microfabricated channels and incorporation of CGE with two-dimensional protein separations are also discussed in this section. We finally present a few representative applications of CGE for separating proteins in real-world samples.
Source: Analytica Chimica Acta, Available online 19 October 2011
Zaifang Zhu, Joann J. Lu, Shaorong Liu
Capillary gel electrophoresis (CGE) has been used for protein separation for more than two decades. Due to the technology advancement, current CGE methods are becoming more and more robust and reliable for protein analysis, and some of the methods have been routinely used for the analysis of protein-based pharmaceuticals and quality controls. In light of this progress, we survey 147 papers related to CGE separations of proteins and present an overview of this technology. We first introduce briefly the early development of CGE. We then review the methodology, in which we specifically describe the matrices, coatings, and detection strategies used in CGE. CGE using microfabricated channels and incorporation of CGE with two-dimensional protein separations are also discussed in this section. We finally present a few representative applications of CGE for separating proteins in real-world samples.
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