Low-power (250-500 mW) pulsed gliding-arc discharge reactors that utilize water sprayed as a fine... more Low-power (250-500 mW) pulsed gliding-arc discharge reactors that utilize water sprayed as a fine aerosol into an argon carrier gas have been previously shown to produce molecular hydrogen (H 2) and hydrogen peroxide (H 2 O 2) with high energy yields. In this paper, optical emission spectroscopy in the range of 230-1000 nm is used to assess the formation of radicals in the plasma region of the reactor as functions of spatial position and liquid flow rate. Radical intensities of OH (309 nm) were the highest at 10 mm downstream from the point of discharge initiation, and the gradient of the OH radical intensities between 10 and 15 mm was higher for the higher liquid flow rates that correspond to the highest production rates and efficiencies of hydrogen peroxide. These results support the hypothesis that hydrogen peroxide production efficiency increases with rapid OH radical quenching.
Journal of chromatography. B, Analytical technologies in the biomedical and life sciences, Jan 15, 2017
Penicillin G has been applied to citrus trees as a potential treatment in the fight against Huang... more Penicillin G has been applied to citrus trees as a potential treatment in the fight against Huanglongbing (HLB). Here, we have developed and validated a method to identify and quantitate penicillin G and two of its metabolites, penillic acid and penilloic acid, in citrus fruit using ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). This method improves upon a previous method by incorporating isotopically labeled internal standards, namely, penillic acid-D5, and penilloic acid-D5. These standards greatly enhanced the accuracy and precision of our measurements by compensating for recovery losses, degradation, and matrix effects. When 2g of citrus fruit sample is extracted, the limits of detection (LOD) were determined to be 0.1ng/g for penicillin G and penilloic acid, and 0.25ng/g for penillic acid. At fortification levels of 0.1, 0.25, 1, and 10ng/g, absolute recoveries for penillic and penilloic acids were generally between 50-70%. Recoveries corre...
A pulsed electrical discharge plasma formed in a tubular reactor with flowing argon carrier gas a... more A pulsed electrical discharge plasma formed in a tubular reactor with flowing argon carrier gas and a liquid water film was analyzed using methylene blue as a liquid phase hydroxyl radical scavenger and simultaneous measurements of hydrogen peroxide formation. The effects of liquid flow rate, liquid conductivity, concentration of dye, and the addition of ferrous ion on dye decoloration and degradation were determined. Higher liquid flow rates and concentrations of dye resulted in less decoloration percentages and hydrogen peroxide formation due to initial liquid conductivity effects and lower residence times in the reactor. The highest decoloration energy yield of dye found in these studies was 5.2g/kWh when using the higher liquid flow rate and adding the catalyst. The non-homogeneous nature of the plasma discharge favors the production of hydrogen peroxide in the plasma-liquid interface over the chemical oxidation of the organic in the bulk liquid phase and post-plasma reactions w...
Pulsed plasma gliding arc reactors utilizing liquid spray have been demonstrated to lead to very ... more Pulsed plasma gliding arc reactors utilizing liquid spray have been demonstrated to lead to very high efficiency production of hydrogen peroxide from water with argon carrier gases, nitrates from water with air carrier gases, and molecular hydrogen from organic liquids, e.g. methanol, using argon carrier gases. A gliding arc electrical discharge plasma is generated using two knife-edge electrodes separated by a small gap distance. The carrier gas (2 lpm) containing micrometer size liquid droplets (20 ml/min) flows between the electrodes where a pulse forming circuit delivers relatively low power in the range 200 – 300 mW. In the case of hydrogen peroxide generation, an energy yield of approximately 80 g/kwh has been obtained and this is close to 25% of the thermodynamic limits. Survey of all plasma processes that have been reported to generate hydrogen peroxide show this method to be highly competitive. This method has a major advantage over other chemical methods because only pure ...
ABSTRACT form only given. Electrical discharges in gas-liquid environments and in liquids (includ... more ABSTRACT form only given. Electrical discharges in gas-liquid environments and in liquids (including water and a range of organic compounds) have been studied for applications in electrical transmission, chemical destruction in pollution control, chemical synthesis, polymerization and polymer surface treatment, biological inactivation and biomedical treatments, and materials and nano-particle synthesis, and combustion. It has been found that for the purposes of chemical synthesis plasma generated by moderate frequency low energy pulses in a flowing carrier gas with the addition of a spray of fine aerosol particles or a thin film of liquid leads to the highest energy yield for the production of hydrogen peroxide from pure water. Previous work supports the hypothesis that, in the case of hydrogen peroxide generation by plasma with water droplets, the water droplets function to collect the gas phase generated hydrogen peroxide as well as to provide a large source of water molecules to the plasma. At low plasma power the water droplets are not fully vaporized, and due to the high solubility of hydrogen peroxide in water, the hydrogen peroxide formed in the gas phase is captured by the liquid water droplets where the plasma generated radicals do not cause significant degradation. In addition, large temporal and spatial gradients in the plasma reactor lead to more efficient utilization of the plasma to synthesize hydrogen peroxide. Using inspiration and techniques developed in the previous work with water, the main objective of the present work is to develop and explore the synthesis of organic compounds from organic liquid droplets injected into the plasma. The focus is on hydrocarbons that are liquids at room temperature (e.g., hexane). Plasma processes with liquid organic droplets and thin liquid films may provide the means to introduce reactive species (e.g., OH and H radicals) into organic compounds through spatial and temporal control of the plasma.
We developed and validated a method for the extraction, identification, and quantitation of four ... more We developed and validated a method for the extraction, identification, and quantitation of four nitrofuran metabolites, 3-amino-2-oxazolidinone (AOZ), 3-amino-5-morpholinomethyl-2-oxazolidinone (AMOZ), semicarbazide (SC), and 1-aminohydantoin (AHD), as well as chloramphenicol and florfenicol in a variety of seafood commodities. Samples were extracted by liquid-liquid extraction techniques, analyzed by ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS), and quantitated using commercially sourced, derivatized nitrofuran metabolites, with their isotopically labeled internal standards in-solvent. We obtained recoveries of 90-100% at various fortification levels. The limit of detection (LOD) was set at 0.25 ng/g for AMOZ and AOZ, 1 ng/g for AHD and SC, and 0.1 ng/g for the phenicols. Various extraction methods, standard stability, derivatization efficiency, and improvements to conventional quantitation techniques were also investigated. We successfully applied this method to the identification and quantitation of nitrofuran metabolites and phenicols in 102 imported seafood products. Our results revealed that four of the samples contained residues from banned veterinary drugs.
We developed and validated a method for the extraction, identification, and quantitation of four ... more We developed and validated a method for the extraction, identification, and quantitation of four nitrofuran metabolites, 3-amino-2-oxazolidinone (AOZ), 3-amino-5-morpholinomethyl-2-oxazolidinone (AMOZ), semicarbazide (SC), and 1-aminohydantoin (AHD), as well as chloramphenicol and florfenicol in a variety of seafood commodities. Samples were extracted by liquid-liquid extraction techniques, analyzed by ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS), and quantitated using commercially sourced, derivatized nitrofuran metabolites, with their isotopically labeled internal standards in-solvent. We obtained recoveries of 90-100% at various fortification levels. The limit of detection (LOD) was set at 0.25 ng/g for AMOZ and AOZ, 1 ng/g for AHD and SC, and 0.1 ng/g for the phenicols. Various extraction methods, standard stability, derivatization efficiency, and improvements to conventional quantitation techniques were also investigated. We successfully applied this method to the identification and quantitation of nitrofuran metabolites and phenicols in 102 imported seafood products. Our results revealed that four of the samples contained residues from banned veterinary drugs.
Low-power (250-500 mW) pulsed gliding-arc discharge reactors that utilize water sprayed as a fine... more Low-power (250-500 mW) pulsed gliding-arc discharge reactors that utilize water sprayed as a fine aerosol into an argon carrier gas have been previously shown to produce molecular hydrogen (H 2) and hydrogen peroxide (H 2 O 2) with high energy yields. In this paper, optical emission spectroscopy in the range of 230-1000 nm is used to assess the formation of radicals in the plasma region of the reactor as functions of spatial position and liquid flow rate. Radical intensities of OH (309 nm) were the highest at 10 mm downstream from the point of discharge initiation, and the gradient of the OH radical intensities between 10 and 15 mm was higher for the higher liquid flow rates that correspond to the highest production rates and efficiencies of hydrogen peroxide. These results support the hypothesis that hydrogen peroxide production efficiency increases with rapid OH radical quenching.
Journal of chromatography. B, Analytical technologies in the biomedical and life sciences, Jan 15, 2017
Penicillin G has been applied to citrus trees as a potential treatment in the fight against Huang... more Penicillin G has been applied to citrus trees as a potential treatment in the fight against Huanglongbing (HLB). Here, we have developed and validated a method to identify and quantitate penicillin G and two of its metabolites, penillic acid and penilloic acid, in citrus fruit using ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). This method improves upon a previous method by incorporating isotopically labeled internal standards, namely, penillic acid-D5, and penilloic acid-D5. These standards greatly enhanced the accuracy and precision of our measurements by compensating for recovery losses, degradation, and matrix effects. When 2g of citrus fruit sample is extracted, the limits of detection (LOD) were determined to be 0.1ng/g for penicillin G and penilloic acid, and 0.25ng/g for penillic acid. At fortification levels of 0.1, 0.25, 1, and 10ng/g, absolute recoveries for penillic and penilloic acids were generally between 50-70%. Recoveries corre...
A pulsed electrical discharge plasma formed in a tubular reactor with flowing argon carrier gas a... more A pulsed electrical discharge plasma formed in a tubular reactor with flowing argon carrier gas and a liquid water film was analyzed using methylene blue as a liquid phase hydroxyl radical scavenger and simultaneous measurements of hydrogen peroxide formation. The effects of liquid flow rate, liquid conductivity, concentration of dye, and the addition of ferrous ion on dye decoloration and degradation were determined. Higher liquid flow rates and concentrations of dye resulted in less decoloration percentages and hydrogen peroxide formation due to initial liquid conductivity effects and lower residence times in the reactor. The highest decoloration energy yield of dye found in these studies was 5.2g/kWh when using the higher liquid flow rate and adding the catalyst. The non-homogeneous nature of the plasma discharge favors the production of hydrogen peroxide in the plasma-liquid interface over the chemical oxidation of the organic in the bulk liquid phase and post-plasma reactions w...
Pulsed plasma gliding arc reactors utilizing liquid spray have been demonstrated to lead to very ... more Pulsed plasma gliding arc reactors utilizing liquid spray have been demonstrated to lead to very high efficiency production of hydrogen peroxide from water with argon carrier gases, nitrates from water with air carrier gases, and molecular hydrogen from organic liquids, e.g. methanol, using argon carrier gases. A gliding arc electrical discharge plasma is generated using two knife-edge electrodes separated by a small gap distance. The carrier gas (2 lpm) containing micrometer size liquid droplets (20 ml/min) flows between the electrodes where a pulse forming circuit delivers relatively low power in the range 200 – 300 mW. In the case of hydrogen peroxide generation, an energy yield of approximately 80 g/kwh has been obtained and this is close to 25% of the thermodynamic limits. Survey of all plasma processes that have been reported to generate hydrogen peroxide show this method to be highly competitive. This method has a major advantage over other chemical methods because only pure ...
ABSTRACT form only given. Electrical discharges in gas-liquid environments and in liquids (includ... more ABSTRACT form only given. Electrical discharges in gas-liquid environments and in liquids (including water and a range of organic compounds) have been studied for applications in electrical transmission, chemical destruction in pollution control, chemical synthesis, polymerization and polymer surface treatment, biological inactivation and biomedical treatments, and materials and nano-particle synthesis, and combustion. It has been found that for the purposes of chemical synthesis plasma generated by moderate frequency low energy pulses in a flowing carrier gas with the addition of a spray of fine aerosol particles or a thin film of liquid leads to the highest energy yield for the production of hydrogen peroxide from pure water. Previous work supports the hypothesis that, in the case of hydrogen peroxide generation by plasma with water droplets, the water droplets function to collect the gas phase generated hydrogen peroxide as well as to provide a large source of water molecules to the plasma. At low plasma power the water droplets are not fully vaporized, and due to the high solubility of hydrogen peroxide in water, the hydrogen peroxide formed in the gas phase is captured by the liquid water droplets where the plasma generated radicals do not cause significant degradation. In addition, large temporal and spatial gradients in the plasma reactor lead to more efficient utilization of the plasma to synthesize hydrogen peroxide. Using inspiration and techniques developed in the previous work with water, the main objective of the present work is to develop and explore the synthesis of organic compounds from organic liquid droplets injected into the plasma. The focus is on hydrocarbons that are liquids at room temperature (e.g., hexane). Plasma processes with liquid organic droplets and thin liquid films may provide the means to introduce reactive species (e.g., OH and H radicals) into organic compounds through spatial and temporal control of the plasma.
We developed and validated a method for the extraction, identification, and quantitation of four ... more We developed and validated a method for the extraction, identification, and quantitation of four nitrofuran metabolites, 3-amino-2-oxazolidinone (AOZ), 3-amino-5-morpholinomethyl-2-oxazolidinone (AMOZ), semicarbazide (SC), and 1-aminohydantoin (AHD), as well as chloramphenicol and florfenicol in a variety of seafood commodities. Samples were extracted by liquid-liquid extraction techniques, analyzed by ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS), and quantitated using commercially sourced, derivatized nitrofuran metabolites, with their isotopically labeled internal standards in-solvent. We obtained recoveries of 90-100% at various fortification levels. The limit of detection (LOD) was set at 0.25 ng/g for AMOZ and AOZ, 1 ng/g for AHD and SC, and 0.1 ng/g for the phenicols. Various extraction methods, standard stability, derivatization efficiency, and improvements to conventional quantitation techniques were also investigated. We successfully applied this method to the identification and quantitation of nitrofuran metabolites and phenicols in 102 imported seafood products. Our results revealed that four of the samples contained residues from banned veterinary drugs.
We developed and validated a method for the extraction, identification, and quantitation of four ... more We developed and validated a method for the extraction, identification, and quantitation of four nitrofuran metabolites, 3-amino-2-oxazolidinone (AOZ), 3-amino-5-morpholinomethyl-2-oxazolidinone (AMOZ), semicarbazide (SC), and 1-aminohydantoin (AHD), as well as chloramphenicol and florfenicol in a variety of seafood commodities. Samples were extracted by liquid-liquid extraction techniques, analyzed by ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS), and quantitated using commercially sourced, derivatized nitrofuran metabolites, with their isotopically labeled internal standards in-solvent. We obtained recoveries of 90-100% at various fortification levels. The limit of detection (LOD) was set at 0.25 ng/g for AMOZ and AOZ, 1 ng/g for AHD and SC, and 0.1 ng/g for the phenicols. Various extraction methods, standard stability, derivatization efficiency, and improvements to conventional quantitation techniques were also investigated. We successfully applied this method to the identification and quantitation of nitrofuran metabolites and phenicols in 102 imported seafood products. Our results revealed that four of the samples contained residues from banned veterinary drugs.
Uploads
Papers by Kevin Hsieh