The Experts below are selected from a list of 1134 Experts worldwide ranked by ideXlab platform
Tatsuhiko Tanaka - One of the best experts on this subject based on the ideXlab platform.
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evaluation of certified reference materials for oxidation reduction titration by precise coulometric titration and volumetric analysis
Analytica Chimica Acta, 2006Co-Authors: Toshiaki Asakai, Mariko Murayama, Yoshihiro Kakihara, Yasuharu Kozuka, Sadao Hossaka, Tatsuhiko TanakaAbstract:Abstract The accuracy and uncertainty of coulometric titration of Japanese certified reference materials (CRMs) for oxidation–reduction titration were examined in this study. The results for potassium Dichromate, Sodium oxalate, and potassium iodate are presented. Potassium Dichromate was directly determined by coulometric titration, and Sodium oxalate and potassium iodate were determined by volumetric analysis using potassium Dichromate assigned by coulometry. The uncertainty of the method was investigated by examining the dependency on the sample size and on the electrolysis current. Changes in the titration parameters did not result in any significant effects on the titration results. The coulometric system used primarily consists of a constant current source, timer, switching circuit, indicator unit, and voltmeter. They were controlled using the coulometry software by a PC/AT compatible computer. A highly automated coulometric system achieves repeatabilities of less than one part in 30,000 ( k = 2) and uncertainties of less than one part in 15,000 ( k = 2). In addition, using volumetric method, SI units traceable Sodium oxalate and potassium iodate (purity standards for redox reaction) CRMs were developed. Reference materials for volumetric analysis are the most basic substances used in analytical chemistry. These materials are analyzed by several analytical methods and are produced globally; however, their purities have not been compared at the international level. Therefore, the relationship between the purity and reliability of these materials has not yet been established. In this paper, we determine the relationship between these parameters by titrating each material obtained from different laboratories.
Toshiaki Asakai - One of the best experts on this subject based on the ideXlab platform.
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evaluation of certified reference materials for oxidation reduction titration by precise coulometric titration and volumetric analysis
Analytica Chimica Acta, 2006Co-Authors: Toshiaki Asakai, Mariko Murayama, Yoshihiro Kakihara, Yasuharu Kozuka, Sadao Hossaka, Tatsuhiko TanakaAbstract:Abstract The accuracy and uncertainty of coulometric titration of Japanese certified reference materials (CRMs) for oxidation–reduction titration were examined in this study. The results for potassium Dichromate, Sodium oxalate, and potassium iodate are presented. Potassium Dichromate was directly determined by coulometric titration, and Sodium oxalate and potassium iodate were determined by volumetric analysis using potassium Dichromate assigned by coulometry. The uncertainty of the method was investigated by examining the dependency on the sample size and on the electrolysis current. Changes in the titration parameters did not result in any significant effects on the titration results. The coulometric system used primarily consists of a constant current source, timer, switching circuit, indicator unit, and voltmeter. They were controlled using the coulometry software by a PC/AT compatible computer. A highly automated coulometric system achieves repeatabilities of less than one part in 30,000 ( k = 2) and uncertainties of less than one part in 15,000 ( k = 2). In addition, using volumetric method, SI units traceable Sodium oxalate and potassium iodate (purity standards for redox reaction) CRMs were developed. Reference materials for volumetric analysis are the most basic substances used in analytical chemistry. These materials are analyzed by several analytical methods and are produced globally; however, their purities have not been compared at the international level. Therefore, the relationship between the purity and reliability of these materials has not yet been established. In this paper, we determine the relationship between these parameters by titrating each material obtained from different laboratories.
Cheng-wei Li - One of the best experts on this subject based on the ideXlab platform.
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volumetric and viscosity behaviors of the chromic anhydride Sodium Dichromate Sodium chromate water from 298 15 to 333 15 k
Journal of Molecular Liquids, 2008Co-Authors: Peng Zhang, Ji-yan Wang, Fu-an Wang, Cheng-wei LiAbstract:Abstract The densities and viscosities of chromic anhydride + Sodium Dichromate + Sodium chromate + water quaternary mixtures and Sodium Dichromate + Sodium chromate + water ternary mixtures have been measured at the temperatures(298.15, 303.15, 313.15, 323.15 and 333.15)K. The experimental data were correlated with the Vogel–Tamman–Fulcher equation. The apparent molar volumes, limiting partial molar volumes and viscosity B-coefficient of chromic anhydride were calculated from the experimental measurements. The solute–solute interactions, solute-mixed solvent interactions and the structural-making effect of chromic anhydride have been discussed using Hepler criterion and Jones–Dole equation.
Robinson Carol M. - One of the best experts on this subject based on the ideXlab platform.
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Environmental issues relating to the manufacture of antisense-based products of phamaceutical biotechnology.
'Glucksman Library University of Limerick', 2011Co-Authors: Robinson Carol M.Abstract:Antisense technology is a nucleic acid-based approach capable of down regulating the expression of specific genes. Several antisense drugs have or will shortly gain approval for medical use. Phosphorothioate oligonucleotides (PS oligonucleotides), in which one of the non-bridging oxygen atoms of the internucleotide phosphodiester linkage is replaced by a sulfur atom is one of the most extensively used backbone modifications of antisense oligonucleotides. Therefore, they are the focus of this study. Their unique manufacturing routes and bioactivity raises hitherto, unaddressed environmental issues. The manufacture and use of antisense oligonucleotides at industrial scale could result in its unintentional release to waste streams and hence into the environment. This research aims to determine the environmental issues associated with the production lifecycle of an antisense drug and to develop effective treatment processes to degrade/remove antisense drugs from specific manufacturing waste streams. The composition of waste streams generated from each process step of the synthesis was identified and simulated using SuperPro Designer® 6.0 flow sheets. This study highlighted that large quantities of chemical wastes, most specifically, significant volumes of acetonitrile (2037 L) and toluene (1018 L) are produced during the synthesis of crude 20-mer PS oligonucleotide at 1.5 kg scale. It is predominantly during downstream processing, in particular purification, that there is a potential for loss of synthetic nucleic acid material during which it is estimated that upwards of 50% of synthetic oligonucleotide (750 g) is lost to waste streams. In this study, the main strategies adapted for the degradation and removal of antisense oligonucleotides include physical heat treatment, acidic and basic pH at ambient room temperature and in combination with elevated temperature (Chapter Three), chemical treatment with soft metal ions (silver nitrate) and oxidising agents (iodine, potassium permanganate, potassium Dichromate, Sodium hypochlorite, peracetic acid, hydrogen peroxide and Virkon®) (Chapter Four) and enzymatic treatment with commercially available nucleases (Chapter Five). Analysis was undertaken both qualitatively and quantitatively using Polyacrylamide Gel Electrophoresis and Ion-Pair Reversed-Phase chromatography. Based upon the concentration of reagents required, treatment duration, economic considerations and potential environmental impacts, six optimum treatments were chosen. These include treatment with low pH (HCl, 0.5 M) at 40°C, low pH (H2SO4, 0.5 M) at 40°C, iodine (25 mM), potassium Dichromate (0.125 M), nuclease P1 (5 U/ml) and steam sterilisation for their efficacy in a simulated waste stream environment. Steam sterilisation was ineffective at degrading the PS oligonucleotides in the waste stream solution. Treatment with nuclease P1 was the most effective treatment process degrading the PS oligonucleotide by 96.9%. The next most effective treatment method was low pH with HCl at 40ºC, low pH with H2SO4 at 40ºC, acidic potassium Dichromate and iodine degrading the PS oligonucleotide in simulated waste stream conditions by 92.9, 92.4, 88.3 and 86.7%, respectively. The application of low pH with HCl at 40ºC or nuclease P1 presented as the most effective treatment methods of degrading the PS oligonucleotides in the simulated purification waste stream and demonstrated their suitability as the most technically feasible and eco-friendly methods of treatment. These methodologies may potentially be used to treat PS oligonucleotide containing waste streams, rendering them free of active drug product.EP
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Environmental issues relating to the manufacture of antisense-based products of phamaceutical biotechnology.
'Glucksman Library University of Limerick', 2011Co-Authors: Robinson Carol M.Abstract:peer-reviewedAntisense technology is a nucleic acid-based approach capable of down regulating the expression of specific genes. Several antisense drugs have or will shortly gain approval for medical use. Phosphorothioate oligonucleotides (PS oligonucleotides), in which one of the non-bridging oxygen atoms of the internucleotide phosphodiester linkage is replaced by a sulfur atom is one of the most extensively used backbone modifications of antisense oligonucleotides. Therefore, they are the focus of this study. Their unique manufacturing routes and bioactivity raises hitherto, unaddressed environmental issues. The manufacture and use of antisense oligonucleotides at industrial scale could result in its unintentional release to waste streams and hence into the environment. This research aims to determine the environmental issues associated with the production lifecycle of an antisense drug and to develop effective treatment processes to degrade/remove antisense drugs from specific manufacturing waste streams. The composition of waste streams generated from each process step of the synthesis was identified and simulated using SuperPro Designer® 6.0 flow sheets. This study highlighted that large quantities of chemical wastes, most specifically, significant volumes of acetonitrile (2037 L) and toluene (1018 L) are produced during the synthesis of crude 20-mer PS oligonucleotide at 1.5 kg scale. It is predominantly during downstream processing, in particular purification, that there is a potential for loss of synthetic nucleic acid material during which it is estimated that upwards of 50% of synthetic oligonucleotide (750 g) is lost to waste streams. In this study, the main strategies adapted for the degradation and removal of antisense oligonucleotides include physical heat treatment, acidic and basic pH at ambient room temperature and in combination with elevated temperature (Chapter Three), chemical treatment with soft metal ions (silver nitrate) and oxidising agents (iodine, potassium permanganate, potassium Dichromate, Sodium hypochlorite, peracetic acid, hydrogen peroxide and Virkon®) (Chapter Four) and enzymatic treatment with commercially available nucleases (Chapter Five). Analysis was undertaken both qualitatively and quantitatively using Polyacrylamide Gel Electrophoresis and Ion-Pair Reversed-Phase chromatography. Based upon the concentration of reagents required, treatment duration, economic considerations and potential environmental impacts, six optimum treatments were chosen. These include treatment with low pH (HCl, 0.5 M) at 40°C, low pH (H2SO4, 0.5 M) at 40°C, iodine (25 mM), potassium Dichromate (0.125 M), nuclease P1 (5 U/ml) and steam sterilisation for their efficacy in a simulated waste stream environment. Steam sterilisation was ineffective at degrading the PS oligonucleotides in the waste stream solution. Treatment with nuclease P1 was the most effective treatment process degrading the PS oligonucleotide by 96.9%. The next most effective treatment method was low pH with HCl at 40ºC, low pH with H2SO4 at 40ºC, acidic potassium Dichromate and iodine degrading the PS oligonucleotide in simulated waste stream conditions by 92.9, 92.4, 88.3 and 86.7%, respectively. The application of low pH with HCl at 40ºC or nuclease P1 presented as the most effective treatment methods of degrading the PS oligonucleotides in the simulated purification waste stream and demonstrated their suitability as the most technically feasible and eco-friendly methods of treatment. These methodologies may potentially be used to treat PS oligonucleotide containing waste streams, rendering them free of active drug product.EP
Yoshihiro Kakihara - One of the best experts on this subject based on the ideXlab platform.
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evaluation of certified reference materials for oxidation reduction titration by precise coulometric titration and volumetric analysis
Analytica Chimica Acta, 2006Co-Authors: Toshiaki Asakai, Mariko Murayama, Yoshihiro Kakihara, Yasuharu Kozuka, Sadao Hossaka, Tatsuhiko TanakaAbstract:Abstract The accuracy and uncertainty of coulometric titration of Japanese certified reference materials (CRMs) for oxidation–reduction titration were examined in this study. The results for potassium Dichromate, Sodium oxalate, and potassium iodate are presented. Potassium Dichromate was directly determined by coulometric titration, and Sodium oxalate and potassium iodate were determined by volumetric analysis using potassium Dichromate assigned by coulometry. The uncertainty of the method was investigated by examining the dependency on the sample size and on the electrolysis current. Changes in the titration parameters did not result in any significant effects on the titration results. The coulometric system used primarily consists of a constant current source, timer, switching circuit, indicator unit, and voltmeter. They were controlled using the coulometry software by a PC/AT compatible computer. A highly automated coulometric system achieves repeatabilities of less than one part in 30,000 ( k = 2) and uncertainties of less than one part in 15,000 ( k = 2). In addition, using volumetric method, SI units traceable Sodium oxalate and potassium iodate (purity standards for redox reaction) CRMs were developed. Reference materials for volumetric analysis are the most basic substances used in analytical chemistry. These materials are analyzed by several analytical methods and are produced globally; however, their purities have not been compared at the international level. Therefore, the relationship between the purity and reliability of these materials has not yet been established. In this paper, we determine the relationship between these parameters by titrating each material obtained from different laboratories.