The Experts below are selected from a list of 225 Experts worldwide ranked by ideXlab platform
Damia Barcelo - One of the best experts on this subject based on the ideXlab platform.
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fast and comprehensive multi residue analysis of a broad Range of human and veterinary pharmaceuticals and some of their metabolites in surface and treated waters by ultra high performance liquid chromatography coupled to quadrupole linear ion trap t
Journal of Chromatography A, 2012Co-Authors: Meritxell Gros, Damia Barcelo, Sara RodriguezmozazAbstract:The present work describes the development of an analytical method, based on automated off-line solid phase extraction (SPE) followed by ultra-high-performance liquid chromatography coupled to quadrupole linear ion trap tandem mass spectrometry (UPLC-QqLIT) for the determination of 81 pharmaceutical residues, covering various therapeutic groups, and some of their main metabolites, in surface and treated waters (influent and effluent wastewaters, river, reservoir, sea and drinking water). For unequivocal identification and confirmation, two selected reaction monitoring (SRM) transitions per compound are monitored. Quantification is performed by the internal standard approach, indispensable to correct matrix effects. Moreover, to obtain an extra tool for confirmation of positive findings, an information dependent acquisition (IDA) experiment was performed, with SRM as survey scan and an enhanced product ion (EPI) scan as dependent scan. Compound identification was carried out by library search, matching the EPI spectra achieved at one fixed collision energy with those present in a library. The main advantages of the method are automation and speed-up of sample preparation by the reduction of extraction volumes for some matrices, the fast separation of a big number of pharmaceuticals, its high sensitivity (limits of detection in the low ng/L Range), Selectivity, due to the use of tandem mass spectrometry, reliability since a significant number of isotopically labeled compounds are used as internal standards for quantification and finally, the analysis of tap, reservoir and sea waters, since information about occurrence of pharmaceuticals in these matrices is still sparse. As part of the validation procedure, the method developed was applied to the analysis of pharmaceutical residues in waste and surface waters from different sites in Catalonia (North East of Spain).
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fully automated determination of 74 pharmaceuticals in environmental and waste waters by online solid phase extraction liquid chromatography electrospray tandem mass spectrometry
Talanta, 2010Co-Authors: Rebeca Lopezserna, Sandra Perez, Antoni Ginebreda, Mira Petrovic, Damia BarceloAbstract:Abstract The present work describes the development of a fully automated method, based on on-line solid-phase extraction (SPE)–liquid chromatography-electrospray–tandem mass spectrometry (LC–MS–MS), for the determination of 74 pharmaceuticals in environmental waters (superficial water and groundwater) as well as sewage waters. On-line SPE is performed by passing 2.5 mL of the water sample through a HySphere Resin GP cartridge. For unequivocal identification and confirmation two selected reaction monitoring (SRM) transitions are monitored per compound, thus four identification points are achieved. Quantification is performed by the internal standard approach, indispensable to correct the losses during the solid phase extraction, as well as the matrix effects. The main advantages of the method developed are high sensitivity (limits of detection in the low ng L −1 Range), Selectivity due the use of tandem mass spectrometry and reliability due the use of 51 surrogates and minimum sample manipulation. As a part of the validation procedure, the method developed has been applied to the analysis of various environmental and sewage samples from a Spanish river and a sewage treatment plant.
Takaaki Hanaoka - One of the best experts on this subject based on the ideXlab platform.
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A novel, disposable, screen-printed amperometric biosensor for ketone 3-β-hydroxybutyrate fabricated using a 3-β-hydroxybutyrate dehydrogenase–mesoporous silica conjugate
Analytical and Bioanalytical Chemistry, 2013Co-Authors: Takeshi Shimomura, Touru Sumiya, Masatoshi Ono, Tetsuji Ito, Takaaki HanaokaAbstract:A disposable amperometric biosensor for ketone 3-β-hydroxybutyrate (3HB) has been developed successfully. The sensor is based on a screen-printed carbon electrode containing Meldola’s Blue (MB) and sensing components containing nicotinamide adenine dinucleotide (NAD^+) and 3-β-hydroxybutyrate dehydrogenase (3HBDH) immobilized in mesoporous silica (FSM8.0) using an aqueous photo-cross-linkable polymer matrix of polyvinyl alcohol (O-391), and it requires only a small sample volume of 10 μL for the measurement. The behavior of a resulting biosensor, i.e., 3HBDH–FSM8.0/NAD^+/MB-SPCE, was examined in terms of NAD^+ concentration for construction, pH, applied potential, operational Range, Selectivity, and storage stability. The sensor showed an optimum response at a pH of 7.6 and at an applied potential of −50 mV. The determination Range and the response time for 3HB were from 30 μM to 8 mM and approximately 30 s, respectively. In addition, the sensor was quite stable and maintained >90 % of its initial response after being stored for over 6 months. This result implies that our method provides a novel biosensor for ketone 3-β-hydroxybutyrate which is easy-to-use, cost-effective, and has good reproducibility, which are vital for commercial purposes. Figure Layer structure and operation mechanism of 3HB biosensor
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a novel disposable screen printed amperometric biosensor for ketone 3 β hydroxybutyrate fabricated using a 3 β hydroxybutyrate dehydrogenase mesoporous silica conjugate
Analytical and Bioanalytical Chemistry, 2013Co-Authors: Takeshi Shimomura, Touru Sumiya, Takaaki HanaokaAbstract:A disposable amperometric biosensor for ketone 3-β-hydroxybutyrate (3HB) has been developed successfully. The sensor is based on a screen-printed carbon electrode containing Meldola’s Blue (MB) and sensing components containing nicotinamide adenine dinucleotide (NAD+) and 3-β-hydroxybutyrate dehydrogenase (3HBDH) immobilized in mesoporous silica (FSM8.0) using an aqueous photo-cross-linkable polymer matrix of polyvinyl alcohol (O-391), and it requires only a small sample volume of 10 μL for the measurement. The behavior of a resulting biosensor, i.e., 3HBDH–FSM8.0/NAD+/MB-SPCE, was examined in terms of NAD+ concentration for construction, pH, applied potential, operational Range, Selectivity, and storage stability. The sensor showed an optimum response at a pH of 7.6 and at an applied potential of −50 mV. The determination Range and the response time for 3HB were from 30 μM to 8 mM and approximately 30 s, respectively. In addition, the sensor was quite stable and maintained >90 % of its initial response after being stored for over 6 months. This result implies that our method provides a novel biosensor for ketone 3-β-hydroxybutyrate which is easy-to-use, cost-effective, and has good reproducibility, which are vital for commercial purposes.
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Amperometric detection of phenolic compounds with enzyme immobilized in mesoporous silica prepared by electrophoretic deposition
Sensors and Actuators B: Chemical, 2011Co-Authors: Shimomura Takeshi, Tetsuji Itoh, Touru Sumiya, Takaaki Hanaoka, Fujio Mizukami, Masatoshi OnoAbstract:Abstract Laccase was immobilized in mesoporous silica powder with a 7.0 nm pore diameter (FSM7.0) coated onto a glassy carbon electrode using an electrophoretic deposition technique, and the electrode was then applied to the amperometric detection of catechol, which is a typical phenolic compound. The behavior of a biosensor attached to the electrode was examined in terms of pH, applied potential, sensitivity and operational Range, Selectivity, and storage stability. The sensor showed an optimum response at a pH of 5.0 and at an applied potential of −50 mV. The determination Range and the response time for catechol were 2.0–100 μM and approximately 2 min, respectively. In addition, the sensor was quite stable and retained its initial response without notable change after being stored for over 50 days. This result suggests that our method is quite useful for the fabrication of a high-performance biosensor for practical use.
H.v. Jagadish - One of the best experts on this subject based on the ideXlab platform.
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Range Selectivity estimation for continuous attributes
Proceedings. Eleventh International Conference on Scientific and Statistical Database Management, 1999Co-Authors: F. Korn, T. Johnson, H.v. JagadishAbstract:Many commercial database systems maintain histograms to efficiently estimate query selectivities as part of query optimization. Most work on histogram design is implicitly geared towards discrete or categorical attribute value domains. We consider approaches that are better suited for the continuous valued attributes commonly found in scientific and statistical databases. We propose two methods based on spline functions for estimating the Selectivity of Range queries over univariate and multivariate data. These methods are more accurate than histograms. As the results from our experiments on both real and synthetic data sets demonstrate, the proposed methods achieved substantially better (up to 5.5 times) estimation error than the state-of-the-art histograms, at exactly the same storage space and with comparable CPU runtime overhead; moreover, the superiority of the proposed spline methods is amplified when applied to multivariate data.
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SSDBM - Range Selectivity estimation for continuous attributes
Proceedings. Eleventh International Conference on Scientific and Statistical Database Management, 1Co-Authors: F. Korn, T. Johnson, H.v. JagadishAbstract:Many commercial database systems maintain histograms to efficiently estimate query selectivities as part of query optimization. Most work on histogram design is implicitly geared towards discrete or categorical attribute value domains. We consider approaches that are better suited for the continuous valued attributes commonly found in scientific and statistical databases. We propose two methods based on spline functions for estimating the Selectivity of Range queries over univariate and multivariate data. These methods are more accurate than histograms. As the results from our experiments on both real and synthetic data sets demonstrate, the proposed methods achieved substantially better (up to 5.5 times) estimation error than the state-of-the-art histograms, at exactly the same storage space and with comparable CPU runtime overhead; moreover, the superiority of the proposed spline methods is amplified when applied to multivariate data.
Georg Groth - One of the best experts on this subject based on the ideXlab platform.
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chalcone based selective inhibitors of a c4 plant key enzyme as novel potential herbicides
Scientific Reports, 2016Co-Authors: G T T Nguyen, German Erlenkamp, Holger Gohlke, O Jack, Andreas Kuberl, Michael Bott, Fabio Fiorani, Georg GrothAbstract:Weeds are a challenge for global food production due to their rapidly evolving resistance against herbicides. We have identified chalcones as selective inhibitors of phosphoenolpyruvate carboxylase (PEPC), a key enzyme for carbon fixation and biomass increase in the C4 photosynthetic pathway of many of the world’s most damaging weeds. In contrast, many of the most important crop plants use C3 photosynthesis. Here, we show that 2′,3′,4′,3,4-Pentahydroxychalcone (IC50 = 600 nM) and 2′,3′,4′-Trihydroxychalcone (IC50 = 4.2 μM) are potent inhibitors of C4 PEPC but do not affect C3 PEPC at a same concentration Range (Selectivity factor: 15–45). Binding and modeling studies indicate that the active compounds bind at the same site as malate/aspartate, the natural feedback inhibitors of the C4 pathway. At the whole plant level, both substances showed pronounced growth-inhibitory effects on the C4 weed Amaranthus retroflexus, while there were no measurable effects on oilseed rape, a C3 plant. Growth of selected soil bacteria was not affected by these substances. Our chalcone compounds are the most potent and selective C4 PEPC inhibitors known to date. They offer a novel approach to combat C4 weeds based on a hitherto unexplored mode of allosteric inhibition of a C4 plant key enzyme.
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Chalcone-based Selective Inhibitors of a C_4 Plant Key Enzyme as Novel Potential Herbicides
Scientific Reports, 2016Co-Authors: G T T Nguyen, German Erlenkamp, Holger Gohlke, O Jack, Andreas Kuberl, Michael Bott, Fabio Fiorani, Georg GrothAbstract:Weeds are a challenge for global food production due to their rapidly evolving resistance against herbicides. We have identified chalcones as selective inhibitors of phosphoenolpyruvate carboxylase (PEPC), a key enzyme for carbon fixation and biomass increase in the C_4 photosynthetic pathway of many of the world’s most damaging weeds. In contrast, many of the most important crop plants use C_3 photosynthesis. Here, we show that 2′,3′,4′,3,4-Pentahydroxychalcone (IC_50 = 600 nM) and 2′,3′,4′-Trihydroxychalcone (IC_50 = 4.2 μM) are potent inhibitors of C_4 PEPC but do not affect C_3 PEPC at a same concentration Range (Selectivity factor: 15–45). Binding and modeling studies indicate that the active compounds bind at the same site as malate/aspartate, the natural feedback inhibitors of the C_4 pathway. At the whole plant level, both substances showed pronounced growth-inhibitory effects on the C_4 weed Amaranthus retroflexus , while there were no measurable effects on oilseed rape, a C_3 plant. Growth of selected soil bacteria was not affected by these substances. Our chalcone compounds are the most potent and selective C_4 PEPC inhibitors known to date. They offer a novel approach to combat C_4 weeds based on a hitherto unexplored mode of allosteric inhibition of a C_4 plant key enzyme.
Touru Sumiya - One of the best experts on this subject based on the ideXlab platform.
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A novel, disposable, screen-printed amperometric biosensor for ketone 3-β-hydroxybutyrate fabricated using a 3-β-hydroxybutyrate dehydrogenase–mesoporous silica conjugate
Analytical and Bioanalytical Chemistry, 2013Co-Authors: Takeshi Shimomura, Touru Sumiya, Masatoshi Ono, Tetsuji Ito, Takaaki HanaokaAbstract:A disposable amperometric biosensor for ketone 3-β-hydroxybutyrate (3HB) has been developed successfully. The sensor is based on a screen-printed carbon electrode containing Meldola’s Blue (MB) and sensing components containing nicotinamide adenine dinucleotide (NAD^+) and 3-β-hydroxybutyrate dehydrogenase (3HBDH) immobilized in mesoporous silica (FSM8.0) using an aqueous photo-cross-linkable polymer matrix of polyvinyl alcohol (O-391), and it requires only a small sample volume of 10 μL for the measurement. The behavior of a resulting biosensor, i.e., 3HBDH–FSM8.0/NAD^+/MB-SPCE, was examined in terms of NAD^+ concentration for construction, pH, applied potential, operational Range, Selectivity, and storage stability. The sensor showed an optimum response at a pH of 7.6 and at an applied potential of −50 mV. The determination Range and the response time for 3HB were from 30 μM to 8 mM and approximately 30 s, respectively. In addition, the sensor was quite stable and maintained >90 % of its initial response after being stored for over 6 months. This result implies that our method provides a novel biosensor for ketone 3-β-hydroxybutyrate which is easy-to-use, cost-effective, and has good reproducibility, which are vital for commercial purposes. Figure Layer structure and operation mechanism of 3HB biosensor
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a novel disposable screen printed amperometric biosensor for ketone 3 β hydroxybutyrate fabricated using a 3 β hydroxybutyrate dehydrogenase mesoporous silica conjugate
Analytical and Bioanalytical Chemistry, 2013Co-Authors: Takeshi Shimomura, Touru Sumiya, Takaaki HanaokaAbstract:A disposable amperometric biosensor for ketone 3-β-hydroxybutyrate (3HB) has been developed successfully. The sensor is based on a screen-printed carbon electrode containing Meldola’s Blue (MB) and sensing components containing nicotinamide adenine dinucleotide (NAD+) and 3-β-hydroxybutyrate dehydrogenase (3HBDH) immobilized in mesoporous silica (FSM8.0) using an aqueous photo-cross-linkable polymer matrix of polyvinyl alcohol (O-391), and it requires only a small sample volume of 10 μL for the measurement. The behavior of a resulting biosensor, i.e., 3HBDH–FSM8.0/NAD+/MB-SPCE, was examined in terms of NAD+ concentration for construction, pH, applied potential, operational Range, Selectivity, and storage stability. The sensor showed an optimum response at a pH of 7.6 and at an applied potential of −50 mV. The determination Range and the response time for 3HB were from 30 μM to 8 mM and approximately 30 s, respectively. In addition, the sensor was quite stable and maintained >90 % of its initial response after being stored for over 6 months. This result implies that our method provides a novel biosensor for ketone 3-β-hydroxybutyrate which is easy-to-use, cost-effective, and has good reproducibility, which are vital for commercial purposes.
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Amperometric detection of phenolic compounds with enzyme immobilized in mesoporous silica prepared by electrophoretic deposition
Sensors and Actuators B: Chemical, 2011Co-Authors: Shimomura Takeshi, Tetsuji Itoh, Touru Sumiya, Takaaki Hanaoka, Fujio Mizukami, Masatoshi OnoAbstract:Abstract Laccase was immobilized in mesoporous silica powder with a 7.0 nm pore diameter (FSM7.0) coated onto a glassy carbon electrode using an electrophoretic deposition technique, and the electrode was then applied to the amperometric detection of catechol, which is a typical phenolic compound. The behavior of a biosensor attached to the electrode was examined in terms of pH, applied potential, sensitivity and operational Range, Selectivity, and storage stability. The sensor showed an optimum response at a pH of 5.0 and at an applied potential of −50 mV. The determination Range and the response time for catechol were 2.0–100 μM and approximately 2 min, respectively. In addition, the sensor was quite stable and retained its initial response without notable change after being stored for over 50 days. This result suggests that our method is quite useful for the fabrication of a high-performance biosensor for practical use.
