The Experts below are selected from a list of 28167 Experts worldwide ranked by ideXlab platform
Lars Konermann - One of the best experts on this subject based on the ideXlab platform.
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mechanistic studies on enzymatic Reactions by electrospray ionization ms using a capillary mixer with adjustable Reaction Chamber volume for time resolved measurements
Analytical Chemistry, 2004Co-Authors: Derek J Wilson, Lars KonermannAbstract:Mass spectrometry (MS)-based techniques have enormous potential for kinetic studies on enzyme-catalyzed processes. In particular, the use of electrospray ionization (ESI) MS for steady-state measurements is well established. However, there are very few reports of MS-based studies in the pre-steady-state regime, because it is difficult to achieve the time resolution required for this type of experiment. We have recently developed a capillary mixer with adjustable Reaction Chamber volume for kinetic studies by ESI-MS with millisecond time resolution (Wilson, D. J.; Konermann, L. Anal. Chem. 2003, 75, 6408−6414). Data can be acquired in kinetic mode, where the concentrations of selected reactive species are monitored as a function of time, or in spectral mode, where entire mass spectra are obtained for selected Reaction times. Here, we describe the application of this technique to study the kinetics of enzyme Reactions. The hydrolysis of p-nitrophenyl acetate by chymotrypsin was chosen as a simple chromophor...
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a capillary mixer with adjustable Reaction Chamber volume for millisecond time resolved studies by electrospray mass spectrometry
Analytical Chemistry, 2003Co-Authors: Derek J Wilson, Lars KonermannAbstract:A novel continuous-flow apparatus for on-line kinetic studies of (bio)chemical solution-phase processes by electrospray ionization mass spectrometry (ESI-MS) is described. The device is based on two concentric capillaries. Fluid is released from the inner capillary into the intercapillary space, where it mixes with solution flowing through the outer capillary, thus initiating the Reaction of interest. Gas-phase analyte ions are formed near the tip of the outer capillary by pneumatically assisted ESI. This setup allows the mixer to be placed directly within the ion source, thus providing a minimal dead volume of ∼8 nL. Time-resolved data can be recorded in both “spectral” and “kinetic” modes. In the former case, the position of the inner capillary is fixed at various points, such that entire mass spectra can be recorded for selected Reaction times. For experiments in kinetic mode, the mass spectrometer monitors the signal intensity at selected m/z values, while the inner capillary is continuously pulled ba...
Derek J Wilson - One of the best experts on this subject based on the ideXlab platform.
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mechanistic studies on enzymatic Reactions by electrospray ionization ms using a capillary mixer with adjustable Reaction Chamber volume for time resolved measurements
Analytical Chemistry, 2004Co-Authors: Derek J Wilson, Lars KonermannAbstract:Mass spectrometry (MS)-based techniques have enormous potential for kinetic studies on enzyme-catalyzed processes. In particular, the use of electrospray ionization (ESI) MS for steady-state measurements is well established. However, there are very few reports of MS-based studies in the pre-steady-state regime, because it is difficult to achieve the time resolution required for this type of experiment. We have recently developed a capillary mixer with adjustable Reaction Chamber volume for kinetic studies by ESI-MS with millisecond time resolution (Wilson, D. J.; Konermann, L. Anal. Chem. 2003, 75, 6408−6414). Data can be acquired in kinetic mode, where the concentrations of selected reactive species are monitored as a function of time, or in spectral mode, where entire mass spectra are obtained for selected Reaction times. Here, we describe the application of this technique to study the kinetics of enzyme Reactions. The hydrolysis of p-nitrophenyl acetate by chymotrypsin was chosen as a simple chromophor...
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a capillary mixer with adjustable Reaction Chamber volume for millisecond time resolved studies by electrospray mass spectrometry
Analytical Chemistry, 2003Co-Authors: Derek J Wilson, Lars KonermannAbstract:A novel continuous-flow apparatus for on-line kinetic studies of (bio)chemical solution-phase processes by electrospray ionization mass spectrometry (ESI-MS) is described. The device is based on two concentric capillaries. Fluid is released from the inner capillary into the intercapillary space, where it mixes with solution flowing through the outer capillary, thus initiating the Reaction of interest. Gas-phase analyte ions are formed near the tip of the outer capillary by pneumatically assisted ESI. This setup allows the mixer to be placed directly within the ion source, thus providing a minimal dead volume of ∼8 nL. Time-resolved data can be recorded in both “spectral” and “kinetic” modes. In the former case, the position of the inner capillary is fixed at various points, such that entire mass spectra can be recorded for selected Reaction times. For experiments in kinetic mode, the mass spectrometer monitors the signal intensity at selected m/z values, while the inner capillary is continuously pulled ba...
Edson I Muller - One of the best experts on this subject based on the ideXlab platform.
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green microwave assisted wet digestion method of carbohydrate rich foods with hydrogen peroxide using single Reaction Chamber and further elemental determination using icp oes and icp ms
Microchemical Journal, 2017Co-Authors: Edson I Muller, Aline L H Muller, Cristiano C Muller, Juliana P Souza, Michele S P Enders, Morgana Doneda, Angelica C Frohlich, Gabrielle D Iop, Kellen Francine AnschauAbstract:Abstract A sample preparation method using only H 2 O 2 in the single Reaction Chamber system (SRC-UltraWave™) was proposed for carbohydrate-rich foods (CRFs) digestion and further elemental determination by inductively coupled plasma (ICP) based techniques. The greenness of the proposed method was evaluated based on the Analytical Eco-Scale. Additionally, the digestion efficiency, obtained under different conditions (temperature and volume of H 2 O 2 ), was evaluated based on the concentration of residual carbon (RC). Determination of RC and major elements (Ca, Fe, Mg and Na) were carried out using inductively coupled plasma optical emission spectrometry (ICP-OES), while the minor and toxic elements (As, Ba, Cd, Co, Cu, Mn, Mo, Pb, Sr and Zn) were determined by inductively coupled plasma mass spectrometry (ICP-MS). Digests with lower RC were obtained using 8 mL of 50% H 2 O 2 , 250 °C and 199 bar. Residual carbon lower than 250 and 400 mg L − 1 were obtained for honey and different flours (wheat, corn, cassava and potato), respectively. Maxima sample masses of 0.75 g and 1.25 g were efficiently digested (without insoluble residues) for different flours and honey, respectively. Reference materials (RMs) and certified reference material (CRM) with carbohydrate-rich matrices: corn bran (RM NIST 8433), cotton cellulose (RM IAEA V9) and rice flour (CRM NIST 1568a) were used to evaluate the accuracy of the proposed method. Additionally, accuracy was also evaluated by comparison between results obtained using proposed method and those obtained by microwave-assisted wet digestion (MAWD) with concentrated HNO 3 . Significant differences were not observed when comparing the results of the proposed method with reference values of RMs, CRM and MAWD. Limits of detection obtained by the proposed method were suitable for the quality control analysis of CRFs and ranging from 0.0001 μg g − 1 to 30 μg g − 1 . As water and oxygen are the main products of H 2 O 2 with CRFs, final digests are suitable for ICP-based techniques analysis due to its low acidity and consequent reduction of physical interferences on nebulization devices. Finally, according to the Analytical Eco-Scale, the proposed method was considered an excellent green analysis with final score of 85.
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study and determination of elemental impurities by icp ms in active pharmaceutical ingredients using single Reaction Chamber digestion in compliance with usp requirements
Talanta, 2015Co-Authors: Aline L H Muller, Jussiane S S Oliveira, Paola A Mello, Edson I Muller, Erico M M FloresAbstract:In this work a method for active pharmaceutical ingredients (APIs) digestion using the single Reaction Chamber (SRC-UltraWave™) system was proposed following the new recommendations of United States Pharmacopeia (USP). Levodope (LEVO), primaquine diphosphate (PRIM), propranolol hydrochloride (PROP) and sulfamethoxazole (SULF) were used to evaluate the digestion efficiency of the proposed method. A comparison of digestion efficiency was performed by measuring the carbon content and residual acidity in digests obtained using SRC and in digests obtained using conventional microwave-assisted digestion system (Multiwave(TM)). Three digestion solutions (concentrated HNO3, aqua regia or inverse aqua regia) were evaluated for digestion of APIs. The determination of Cd, Ir, Mn, Mo, Ni, Os, Pb, Pd, Pt, Rh, Ru was performed using inductively coupled plasma mass spectrometry (ICP-MS) in standard mode. Dynamic Reaction cell (DRC) mode was used for the determination of (51)V, (52)Cr, (53)Cr, (63)Cu and (65)Cu in order to solve polyatomic ion interferences. Arsenic and Hg were determined using chemical vapor generation coupled to ICP-MS (FI-CVG-ICP-MS). Masses of 500mg of APIs were efficiently digested in a SRC-UltraWave™ system using only HNO3 and allowing a carbon content lower than 250mg L(-1) in final digests. Inverse aqua regia was suitable for digestion of sample masses up to 250mg allowing the determination of Ir, Pd, Pt, Rh and Ru. By using HNO3 or inverse aqua regia, suitable recoveries were obtained (between 91 and 109%) for all analytes (exception for Os). Limits of quantification were in agreement with USP requirements and they ranged from 0.001 to 0.015µg g(-1) for all elemental impurities (exception for Os). The proposed method was suitable for elemental impurities determination in APIs and it can be used in routine analysis for quality control in pharmaceutical industries.
Aline L H Muller - One of the best experts on this subject based on the ideXlab platform.
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green microwave assisted wet digestion method of carbohydrate rich foods with hydrogen peroxide using single Reaction Chamber and further elemental determination using icp oes and icp ms
Microchemical Journal, 2017Co-Authors: Edson I Muller, Aline L H Muller, Cristiano C Muller, Juliana P Souza, Michele S P Enders, Morgana Doneda, Angelica C Frohlich, Gabrielle D Iop, Kellen Francine AnschauAbstract:Abstract A sample preparation method using only H 2 O 2 in the single Reaction Chamber system (SRC-UltraWave™) was proposed for carbohydrate-rich foods (CRFs) digestion and further elemental determination by inductively coupled plasma (ICP) based techniques. The greenness of the proposed method was evaluated based on the Analytical Eco-Scale. Additionally, the digestion efficiency, obtained under different conditions (temperature and volume of H 2 O 2 ), was evaluated based on the concentration of residual carbon (RC). Determination of RC and major elements (Ca, Fe, Mg and Na) were carried out using inductively coupled plasma optical emission spectrometry (ICP-OES), while the minor and toxic elements (As, Ba, Cd, Co, Cu, Mn, Mo, Pb, Sr and Zn) were determined by inductively coupled plasma mass spectrometry (ICP-MS). Digests with lower RC were obtained using 8 mL of 50% H 2 O 2 , 250 °C and 199 bar. Residual carbon lower than 250 and 400 mg L − 1 were obtained for honey and different flours (wheat, corn, cassava and potato), respectively. Maxima sample masses of 0.75 g and 1.25 g were efficiently digested (without insoluble residues) for different flours and honey, respectively. Reference materials (RMs) and certified reference material (CRM) with carbohydrate-rich matrices: corn bran (RM NIST 8433), cotton cellulose (RM IAEA V9) and rice flour (CRM NIST 1568a) were used to evaluate the accuracy of the proposed method. Additionally, accuracy was also evaluated by comparison between results obtained using proposed method and those obtained by microwave-assisted wet digestion (MAWD) with concentrated HNO 3 . Significant differences were not observed when comparing the results of the proposed method with reference values of RMs, CRM and MAWD. Limits of detection obtained by the proposed method were suitable for the quality control analysis of CRFs and ranging from 0.0001 μg g − 1 to 30 μg g − 1 . As water and oxygen are the main products of H 2 O 2 with CRFs, final digests are suitable for ICP-based techniques analysis due to its low acidity and consequent reduction of physical interferences on nebulization devices. Finally, according to the Analytical Eco-Scale, the proposed method was considered an excellent green analysis with final score of 85.
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study and determination of elemental impurities by icp ms in active pharmaceutical ingredients using single Reaction Chamber digestion in compliance with usp requirements
Talanta, 2015Co-Authors: Aline L H Muller, Jussiane S S Oliveira, Paola A Mello, Edson I Muller, Erico M M FloresAbstract:In this work a method for active pharmaceutical ingredients (APIs) digestion using the single Reaction Chamber (SRC-UltraWave™) system was proposed following the new recommendations of United States Pharmacopeia (USP). Levodope (LEVO), primaquine diphosphate (PRIM), propranolol hydrochloride (PROP) and sulfamethoxazole (SULF) were used to evaluate the digestion efficiency of the proposed method. A comparison of digestion efficiency was performed by measuring the carbon content and residual acidity in digests obtained using SRC and in digests obtained using conventional microwave-assisted digestion system (Multiwave(TM)). Three digestion solutions (concentrated HNO3, aqua regia or inverse aqua regia) were evaluated for digestion of APIs. The determination of Cd, Ir, Mn, Mo, Ni, Os, Pb, Pd, Pt, Rh, Ru was performed using inductively coupled plasma mass spectrometry (ICP-MS) in standard mode. Dynamic Reaction cell (DRC) mode was used for the determination of (51)V, (52)Cr, (53)Cr, (63)Cu and (65)Cu in order to solve polyatomic ion interferences. Arsenic and Hg were determined using chemical vapor generation coupled to ICP-MS (FI-CVG-ICP-MS). Masses of 500mg of APIs were efficiently digested in a SRC-UltraWave™ system using only HNO3 and allowing a carbon content lower than 250mg L(-1) in final digests. Inverse aqua regia was suitable for digestion of sample masses up to 250mg allowing the determination of Ir, Pd, Pt, Rh and Ru. By using HNO3 or inverse aqua regia, suitable recoveries were obtained (between 91 and 109%) for all analytes (exception for Os). Limits of quantification were in agreement with USP requirements and they ranged from 0.001 to 0.015µg g(-1) for all elemental impurities (exception for Os). The proposed method was suitable for elemental impurities determination in APIs and it can be used in routine analysis for quality control in pharmaceutical industries.
Kellen Francine Anschau - One of the best experts on this subject based on the ideXlab platform.
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green microwave assisted wet digestion method of carbohydrate rich foods with hydrogen peroxide using single Reaction Chamber and further elemental determination using icp oes and icp ms
Microchemical Journal, 2017Co-Authors: Edson I Muller, Aline L H Muller, Cristiano C Muller, Juliana P Souza, Michele S P Enders, Morgana Doneda, Angelica C Frohlich, Gabrielle D Iop, Kellen Francine AnschauAbstract:Abstract A sample preparation method using only H 2 O 2 in the single Reaction Chamber system (SRC-UltraWave™) was proposed for carbohydrate-rich foods (CRFs) digestion and further elemental determination by inductively coupled plasma (ICP) based techniques. The greenness of the proposed method was evaluated based on the Analytical Eco-Scale. Additionally, the digestion efficiency, obtained under different conditions (temperature and volume of H 2 O 2 ), was evaluated based on the concentration of residual carbon (RC). Determination of RC and major elements (Ca, Fe, Mg and Na) were carried out using inductively coupled plasma optical emission spectrometry (ICP-OES), while the minor and toxic elements (As, Ba, Cd, Co, Cu, Mn, Mo, Pb, Sr and Zn) were determined by inductively coupled plasma mass spectrometry (ICP-MS). Digests with lower RC were obtained using 8 mL of 50% H 2 O 2 , 250 °C and 199 bar. Residual carbon lower than 250 and 400 mg L − 1 were obtained for honey and different flours (wheat, corn, cassava and potato), respectively. Maxima sample masses of 0.75 g and 1.25 g were efficiently digested (without insoluble residues) for different flours and honey, respectively. Reference materials (RMs) and certified reference material (CRM) with carbohydrate-rich matrices: corn bran (RM NIST 8433), cotton cellulose (RM IAEA V9) and rice flour (CRM NIST 1568a) were used to evaluate the accuracy of the proposed method. Additionally, accuracy was also evaluated by comparison between results obtained using proposed method and those obtained by microwave-assisted wet digestion (MAWD) with concentrated HNO 3 . Significant differences were not observed when comparing the results of the proposed method with reference values of RMs, CRM and MAWD. Limits of detection obtained by the proposed method were suitable for the quality control analysis of CRFs and ranging from 0.0001 μg g − 1 to 30 μg g − 1 . As water and oxygen are the main products of H 2 O 2 with CRFs, final digests are suitable for ICP-based techniques analysis due to its low acidity and consequent reduction of physical interferences on nebulization devices. Finally, according to the Analytical Eco-Scale, the proposed method was considered an excellent green analysis with final score of 85.