The Experts below are selected from a list of 12 Experts worldwide ranked by ideXlab platform
Frank-michael Matysik - One of the best experts on this subject based on the ideXlab platform.
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Determination of hydrazines by chip electrophoresis with contactless conductivity detection.
Electrophoresis, 2011Co-Authors: Ashwini Kumar, Jacob Burns, Werner Hoffmann, Horst Demattio, Ashok Kumar Malik, Frank-michael MatysikAbstract:In this report, a new approach for the fast determination of hydrazine compounds (hy) in complex matrices is presented. The experimental protocol is based on poly(methylmethacrylate) (PMMA) microchip separations with contactless conductivity detection using a compact portable device, which integrates all separation and detection components. Three hy (hydrozine (Hy), methylhydrazine (MH), and 1,1-dimethylhydrazine (UDMH)) were separated within < 30 s at a separation voltage of 3.8 kV using a L(-)-histidine/2-(N-morpholinoethanesulfonic Acid) (His/MES) buffer (25:50 mM, pH 5.87). The contactless conductivity detection enables detection limits for Hy, MH, and UDMH of 11.9, 35.5, and 337.8 ng/mL, respectively, with linear concentration dependence up to 10 μg/mL. In complex matrices such as soil samples or river water, interferences were eliminated by implementing ultrasound-assisted headspace single-drop microextraction of hy under strongly alkaline conditions, using an aqueous drop of His/MES buffer as the extractant phase. The incorporation of this miniaturized sample preparation step led to improved limits of detection for Hy, MH, and UDMH of 6.5, 15.3, and 11.4 ng/mL, respectively. The overall protocol demonstrates a promising approach for interfacing chip electrophoresis with real-world applications.
Denise Bohrer - One of the best experts on this subject based on the ideXlab platform.
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Contactless Conductivity Detection of 14 Inorganic Cations in Mineral and Phytotherapeutic Formulations after Capillary Electrophoretic Separation
Electroanalysis, 2011Co-Authors: Leandro M. De Carvalho, Alice Raabe, Mariele Martini, Carla S. Sant'anna, Géssica Domingos Da Silveira, Paulo Cícero Do Nascimento, Denise BohrerAbstract:This work describes the separation and determination of 14 inorganic cations (NH4+, K+, Ca2+, Na+, Mg2+, Mn2+, Tl3+, Cr3+, Pb2+, Cd2+, Zn2+, Cu2+, Co2+, and Ni2+) as nutrients and contaminants in mineral and phytotherapeutic samples. The separated species were detected by capacitively coupled contactless conductivity detection (C4D) using working electrolytes based on 30 mmol L−1 2-N-Morpholinoethanesulfonic Acid (MES)/histidine, 1.5 mmol L−1 18-crown-6 ether, and 1 mmol L−1 citric Acid (pH 6.0) as complexing additives for co-migrating cations. The methodology was evaluated and validated for the cations and it was found to be reliable for determining inorganic cations in samples of mineral fertilizers and medicinal plants used in the phytotherapy.
Ashwini Kumar - One of the best experts on this subject based on the ideXlab platform.
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Determination of hydrazines by chip electrophoresis with contactless conductivity detection.
Electrophoresis, 2011Co-Authors: Ashwini Kumar, Jacob Burns, Werner Hoffmann, Horst Demattio, Ashok Kumar Malik, Frank-michael MatysikAbstract:In this report, a new approach for the fast determination of hydrazine compounds (hy) in complex matrices is presented. The experimental protocol is based on poly(methylmethacrylate) (PMMA) microchip separations with contactless conductivity detection using a compact portable device, which integrates all separation and detection components. Three hy (hydrozine (Hy), methylhydrazine (MH), and 1,1-dimethylhydrazine (UDMH)) were separated within < 30 s at a separation voltage of 3.8 kV using a L(-)-histidine/2-(N-morpholinoethanesulfonic Acid) (His/MES) buffer (25:50 mM, pH 5.87). The contactless conductivity detection enables detection limits for Hy, MH, and UDMH of 11.9, 35.5, and 337.8 ng/mL, respectively, with linear concentration dependence up to 10 μg/mL. In complex matrices such as soil samples or river water, interferences were eliminated by implementing ultrasound-assisted headspace single-drop microextraction of hy under strongly alkaline conditions, using an aqueous drop of His/MES buffer as the extractant phase. The incorporation of this miniaturized sample preparation step led to improved limits of detection for Hy, MH, and UDMH of 6.5, 15.3, and 11.4 ng/mL, respectively. The overall protocol demonstrates a promising approach for interfacing chip electrophoresis with real-world applications.
Leandro M. De Carvalho - One of the best experts on this subject based on the ideXlab platform.
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Contactless Conductivity Detection of 14 Inorganic Cations in Mineral and Phytotherapeutic Formulations after Capillary Electrophoretic Separation
Electroanalysis, 2011Co-Authors: Leandro M. De Carvalho, Alice Raabe, Mariele Martini, Carla S. Sant'anna, Géssica Domingos Da Silveira, Paulo Cícero Do Nascimento, Denise BohrerAbstract:This work describes the separation and determination of 14 inorganic cations (NH4+, K+, Ca2+, Na+, Mg2+, Mn2+, Tl3+, Cr3+, Pb2+, Cd2+, Zn2+, Cu2+, Co2+, and Ni2+) as nutrients and contaminants in mineral and phytotherapeutic samples. The separated species were detected by capacitively coupled contactless conductivity detection (C4D) using working electrolytes based on 30 mmol L−1 2-N-Morpholinoethanesulfonic Acid (MES)/histidine, 1.5 mmol L−1 18-crown-6 ether, and 1 mmol L−1 citric Acid (pH 6.0) as complexing additives for co-migrating cations. The methodology was evaluated and validated for the cations and it was found to be reliable for determining inorganic cations in samples of mineral fertilizers and medicinal plants used in the phytotherapy.
Werner Hoffmann - One of the best experts on this subject based on the ideXlab platform.
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Determination of hydrazines by chip electrophoresis with contactless conductivity detection.
Electrophoresis, 2011Co-Authors: Ashwini Kumar, Jacob Burns, Werner Hoffmann, Horst Demattio, Ashok Kumar Malik, Frank-michael MatysikAbstract:In this report, a new approach for the fast determination of hydrazine compounds (hy) in complex matrices is presented. The experimental protocol is based on poly(methylmethacrylate) (PMMA) microchip separations with contactless conductivity detection using a compact portable device, which integrates all separation and detection components. Three hy (hydrozine (Hy), methylhydrazine (MH), and 1,1-dimethylhydrazine (UDMH)) were separated within < 30 s at a separation voltage of 3.8 kV using a L(-)-histidine/2-(N-morpholinoethanesulfonic Acid) (His/MES) buffer (25:50 mM, pH 5.87). The contactless conductivity detection enables detection limits for Hy, MH, and UDMH of 11.9, 35.5, and 337.8 ng/mL, respectively, with linear concentration dependence up to 10 μg/mL. In complex matrices such as soil samples or river water, interferences were eliminated by implementing ultrasound-assisted headspace single-drop microextraction of hy under strongly alkaline conditions, using an aqueous drop of His/MES buffer as the extractant phase. The incorporation of this miniaturized sample preparation step led to improved limits of detection for Hy, MH, and UDMH of 6.5, 15.3, and 11.4 ng/mL, respectively. The overall protocol demonstrates a promising approach for interfacing chip electrophoresis with real-world applications.
