Susanne Wiedmer | University of Helsinki (original) (raw)
Papers by Susanne Wiedmer
Environmental Science: Processes & Impacts, 2023
Oxidized compounds in the atmosphere can occur as emitted primary compounds or as secondary produ... more Oxidized compounds in the atmosphere can occur as emitted primary compounds or as secondary products when volatile emitted precursors react with various oxidants. Due to the presence of polar functional groups, their vapor pressures decrease, and they condense onto small particles. Thereby, they have an effect on climate change by the formation of clouds and scattering solar radiation. The particles and oxidized compounds themselves can cause serious health problems when inhaled. Therefore, it is of utmost importance to study oxidized compounds in the atmosphere. Much ongoing research is focused on the discovery of new oxidized substances and on the evaluation of their sources and factors influencing their formation. Monitoring biogenic and anthropogenic primary oxidized compounds or secondary oxidized products in chamber experiments or field campaigns is common. New discoveries have been reported, including various oxidized compounds and a new group of compounds called highly oxidized organic molecules (HOMs). Analytics of HOMs are mainly focused on chromatography and high-resolution mass spectrometry employing chemical ionization for identifying and quantifying compounds at low concentrations. Oxidized compounds can also be monitored by spectrophotometric methods in which the determinations of total amounts are based on functional groups. This review highlights recent findings on oxidized organic compounds in the atmosphere and analytical methodologies used for their detection and quantification. The discussion includes gas and liquid chromatographic methods, sampling, extraction, concentration, and derivatization procedures involved, as well as mass spectrometric and spectrophotometric methods. Environmental signicance Oxidized compounds in the atmosphere can occur as emitted primary compounds or as secondary products when volatile emitted precursors react with various oxidants. These are currently under intensive investigation due to environmental and health aspects. The discovery of new oxidized species and subsequent evaluation of their sources and factors inuencing their formation is an area of research that has recently received considerable attention. Monitoring of biogenic and anthropogenic primary oxidized compounds or secondary oxidized products in chamber experiments or eld campaigns is common. A new group of compounds called highly oxidized organic molecules (HOMs) has recently been discovered. This review highlights the latest ndings on oxidized organic compounds in the atmosphere and analytical methodologies used to detect and quantify them.
Journal of Pharmaceutical and Biomedical Analysis, Sep 1, 2023
The Royal Society of Chemistry eBooks, Sep 20, 2013
This chapter describes both non-targeted and targeted methods for various metabolic approaches. T... more This chapter describes both non-targeted and targeted methods for various metabolic approaches. The aim is to give the reader a general overview of the various types of chromatographic and electromigration methodologies available for the analysis of specific types of metabolites and to compare their suitabilities for metabolomic analyses.
![Research paper thumbnail of Vapor-liquid equilibrium of the ionic liquid 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-enium acetate and its mixtures with water](https://attachments.academia-assets.com/109953504/thumbnails/1.jpg)
](Ionic liquids have the potential to be used for extracting valuable chemicals from raw materials.... more Ionic liquids have the potential to be used for extracting valuable chemicals from raw materials. These processes often involve water, and after extraction, the water or other chemicals must be removed from the ionic liquid, so it can be reused. To help in designing such processes, we present data on the vapor−liquid equilibrium of the system containing protic ionic liquid 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-enium acetate, water, acetic acid, and 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5ene. Earlier studies have only focused on mixtures of water and an ionic liquid with a stoichiometric ratio of the ions. Here, we also investigated mixtures containing an excess of the acid or base component because in real systems with protic ionic liquids, the amount of acid and base in the mixture can vary. We modeled the data using both the ePC-SAFT and NRTL models, and we compared the performance of different modeling strategies. We also experimentally determined the vapor composition for a few of the samples, but none of the modeling strategies tested could accurately predict the concentration of the acid and base components in the vapor phase.
![Research paper thumbnail of Vapor–Liquid Equilibrium of Ionic Liquid 7-Methyl-1,5,7-triazabicyclo[4.4.0]dec-5-enium Acetate and Its Mixtures with Water](https://attachments.academia-assets.com/109953575/thumbnails/1.jpg)
](Journal of Chemical & Engineering Data, Apr 28, 2020
Ionic liquids have the potential to be used for extracting valuable chemicals from raw materials.... more Ionic liquids have the potential to be used for extracting valuable chemicals from raw materials. These processes often involve water, and after extraction, the water or other chemicals must be removed from the ionic liquid, so it can be reused. To help in designing such processes, we present data on the vapor−liquid equilibrium of the system containing protic ionic liquid 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-enium acetate, water, acetic acid, and 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5ene. Earlier studies have only focused on mixtures of water and an ionic liquid with a stoichiometric ratio of the ions. Here, we also investigated mixtures containing an excess of the acid or base component because in real systems with protic ionic liquids, the amount of acid and base in the mixture can vary. We modeled the data using both the ePC-SAFT and NRTL models, and we compared the performance of different modeling strategies. We also experimentally determined the vapor composition for a few of the samples, but none of the modeling strategies tested could accurately predict the concentration of the acid and base components in the vapor phase.
Chemistry teacher international, Mar 1, 2021
Organic electronics has developed rapidly over the past 40 years. In 1977, a seminal discovery wa... more Organic electronics has developed rapidly over the past 40 years. In 1977, a seminal discovery was reported that showed that a polymer known as polyacetylene could conduct electricity as well as metals could. This was a groundbreaking discovery that led to a Nobel Prize in Chemistry in 2000. The polymers that are used in organic electronics have now been widely studied for use in organic solar cells (OSCs), organic field effect transistors (OFETs), printable electronics, flexible electronics, antistatic coatings, actuators, and more recently in bioelectronics. In particular, the utility of organic electronics is seen in the commercial success of using organic electronic materials in organic light-emitting diodes (OLEDs) where OLED displays can be seen in mobile phones and as flat panel displays. In this paper, we provide a tutorial targeting upper secondary students describing how these special classes of polymers function, and how they can be synthesized. The paper further discusses the use of these materials in two applications: organic solar cells and organic lightemitting diodes. The paper ends with a brief discussion about hands-on activities that can be carried out in the upper secondary student science classroom.
Reviews in Analytical Chemistry, 1999
Langmuir, Jan 19, 2017
Owing to their unique properties and unlimited structural combinations, the ubiquitous use of ion... more Owing to their unique properties and unlimited structural combinations, the ubiquitous use of ionic liquids (ILs) is steadily increasing. The objective of the present work is to shed light into the effects of amidinium-and phosphonium-based ILs on phospholipid vesicles using a nanoplasmonic sensing measurement technique. A new and relatively simple method was developed for the immobilization of large unilamellar vesicles on two different hydrophilic surfaces composed of titanium dioxide and silicon nitride nanolayers. Among the pretreatment conditions studied, vesicle attachment on both substrate materials was achieved with HEPES buffer in the presence of sodium hydroxide and calcium chloride. To get an understanding of how ILs interact with intact vesicles or with supported lipid bilayers, the ionic liquids 1,5-diazabicyclo(4.3.0)non-5-enium acetate ([DBNH][OAc]), tributyl(tetradecyl)phosphonium acetate ([P 14444 ][OAc]), and tributylmethylphosphonium acetate ([P 4441 ][OAc]) were introduced into the biomimetic system and the characteristics of their interactions with the immobilized vesicles were determined. Depending on the IL, in situ real-time IL binding and/or phospholipid removal processes were observed. While [DBNH][OAc] did not have any significant effect on the phospholipid vesicles, the strongest and the most significant effect was observed with [P 14444 ][OAc]. The latter caused clear changes in the phospholipid bilayer: the ILs interacted with the bilayers resulting in deformation of the vesicles most probably due to the formation of vesicle-IL aggregates. Only a mild effect was observed when [P 4441 ][OAc], at a very high concentration, was exposed to the intact vesicles. In general these results led to new insights into the effects of ILs on phospholipid vesicles, which are of great importance for the overall understanding of the harmfulness of ILs on biomembranes and biomimicking systems. In addition, the present work highlights the pivotal role of this highly surface-sensitive indirect biosensing technique in scrutinizing and dissecting the integrity and architecture of phospholipid vesicles in the nanoscale range.
Springer eBooks, 2023
An automated on-line isolation and fractionation system including controlling software was develo... more An automated on-line isolation and fractionation system including controlling software was developed for selected nanosized biomacromolecules from human plasma by on-line coupled immunoaffinity chromatography-asymmetric flow field-flow fractionation (IAC-AsFlFFF). The on-line system was versatile, only different monoclonal antibodies, anti-apolipoprotein B-100, anti-CD9, or anti-CD61, were immobilized on monolithic disk columns for isolation of lipoproteins and extracellular vesicles (EVs). The platelet-derived CD61-positive EVs and CD9-positive EVs, isolated by IAC, were further fractionated by AsFlFFF to their sizebased subpopulations (e.g. exomeres and exosomes) for further analysis. Field-emission scanning electron microscope elucidated the morphology of the subpopulations, and 20 free amino acids and glucose in EV subpopulations were identified and quantified in ng/mL range using hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC-MS/MS). The study revealed that there were significant differences between EV origin and size based subpopulations. The on-line coupled IAC-AsFlFFF system was successfully programmed for reliable execution of 10 sequential isolation and fractionation cycles (37-80 min per cycle) with minimal operator involvement, minimal sample losses, and contamination. The relative standard deviations (RSD) between the cycles for human plasma samples were 0.84-6.6%.
Journal of chromatography open, Nov 1, 2021
Journal of Separation Science, Jun 1, 2009
Nonylphenol ethoxylates (NPEOx) are surfactants which are used worldwide and can be transformed i... more Nonylphenol ethoxylates (NPEOx) are surfactants which are used worldwide and can be transformed in the environment by microorganisms to form nonylphenol (NP). Analysis of these compounds was carried out with micellar electrokinetic capillary chromatography (MEKC). Different parameters such as background electrolyte (BGE) solution, pH, type of surfactant, and sample stacking were optimized. The use of CHES (20 mM, pH 9.1) in combination with 50 mM sodium cholate as a surfactant as BGE solution, together with sample stacking using 50 mM NaCl in the sample and an injection time of 20 s, provided the best separation of the compounds studied. The method was applied to the determination of target analytes in two types of sludge water coming from two steps of a wastewater treatment plant. Liquid–liquid extraction was carried out using toluene as solvent, resulting in recoveries around 100% for all studied analytes. The presence of NPEOx was observed in the first step of the sludge water treatment, based on migration time and UV spectra. Identification was confirmed using tandem MS. LOQs of the studied compounds were in the range of 12.7 to 30.8 ng/mL, which is satisfactory for the analysis of real wastewater samples.
MRS Proceedings, 2012
ABSTRACTHierarchically porous silica monoliths were introduced into liquid phase chromatography a... more ABSTRACTHierarchically porous silica monoliths were introduced into liquid phase chromatography at the beginning of the last decade. The high surface area, high void volume and bicontinuous nature of the porosity of the materials are significant advantages over existing chromatographic supports and have resulted in rapid acceptance of these materials into the chromatography market.We report here on the synthesis of 3-D porous silver, cobalt oxide and zinc oxide monoliths, their materials characterization, fabrication as liquid chromatographic columns and initial chromatographic characterization. The, as prepared, columns gave very low back pressure, consistent with the bicontinuous nature of the columns. Cobalt oxide and zinc oxide both demonstrated retention of a number of nitrogen heterocycles, providing the basis for molecular separation.
Capillary electrochromatography (CEC) is an electromigration separation technique that is a hybri... more Capillary electrochromatography (CEC) is an electromigration separation technique that is a hybrid between capillary electrophoresis and liquid chromatography. This chapter covers the basic principles of the methodology including some theoretical aspects and the instrumentation. CEC can be performed either in packed or open-tubular capillary columns, and the packed capillary columns can be further divided in to particle-packed columns and monolithic columns. The latter are slowly attracting more and more attention. The CEC detection techniques are briefly described with special emphasis on on-line CEC mass spectrometric detection. Some general aspects on miniaturized systems are introduced and finally some typical CEC applications are described.
Environmental Science: Processes & Impacts, 2023
Oxidized compounds in the atmosphere can occur as emitted primary compounds or as secondary produ... more Oxidized compounds in the atmosphere can occur as emitted primary compounds or as secondary products when volatile emitted precursors react with various oxidants. Due to the presence of polar functional groups, their vapor pressures decrease, and they condense onto small particles. Thereby, they have an effect on climate change by the formation of clouds and scattering solar radiation. The particles and oxidized compounds themselves can cause serious health problems when inhaled. Therefore, it is of utmost importance to study oxidized compounds in the atmosphere. Much ongoing research is focused on the discovery of new oxidized substances and on the evaluation of their sources and factors influencing their formation. Monitoring biogenic and anthropogenic primary oxidized compounds or secondary oxidized products in chamber experiments or field campaigns is common. New discoveries have been reported, including various oxidized compounds and a new group of compounds called highly oxidized organic molecules (HOMs). Analytics of HOMs are mainly focused on chromatography and high-resolution mass spectrometry employing chemical ionization for identifying and quantifying compounds at low concentrations. Oxidized compounds can also be monitored by spectrophotometric methods in which the determinations of total amounts are based on functional groups. This review highlights recent findings on oxidized organic compounds in the atmosphere and analytical methodologies used for their detection and quantification. The discussion includes gas and liquid chromatographic methods, sampling, extraction, concentration, and derivatization procedures involved, as well as mass spectrometric and spectrophotometric methods. Environmental signicance Oxidized compounds in the atmosphere can occur as emitted primary compounds or as secondary products when volatile emitted precursors react with various oxidants. These are currently under intensive investigation due to environmental and health aspects. The discovery of new oxidized species and subsequent evaluation of their sources and factors inuencing their formation is an area of research that has recently received considerable attention. Monitoring of biogenic and anthropogenic primary oxidized compounds or secondary oxidized products in chamber experiments or eld campaigns is common. A new group of compounds called highly oxidized organic molecules (HOMs) has recently been discovered. This review highlights the latest ndings on oxidized organic compounds in the atmosphere and analytical methodologies used to detect and quantify them.
Journal of Pharmaceutical and Biomedical Analysis, Sep 1, 2023
The Royal Society of Chemistry eBooks, Sep 20, 2013
This chapter describes both non-targeted and targeted methods for various metabolic approaches. T... more This chapter describes both non-targeted and targeted methods for various metabolic approaches. The aim is to give the reader a general overview of the various types of chromatographic and electromigration methodologies available for the analysis of specific types of metabolites and to compare their suitabilities for metabolomic analyses.
Ionic liquids have the potential to be used for extracting valuable chemicals from raw materials.... more Ionic liquids have the potential to be used for extracting valuable chemicals from raw materials. These processes often involve water, and after extraction, the water or other chemicals must be removed from the ionic liquid, so it can be reused. To help in designing such processes, we present data on the vapor−liquid equilibrium of the system containing protic ionic liquid 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-enium acetate, water, acetic acid, and 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5ene. Earlier studies have only focused on mixtures of water and an ionic liquid with a stoichiometric ratio of the ions. Here, we also investigated mixtures containing an excess of the acid or base component because in real systems with protic ionic liquids, the amount of acid and base in the mixture can vary. We modeled the data using both the ePC-SAFT and NRTL models, and we compared the performance of different modeling strategies. We also experimentally determined the vapor composition for a few of the samples, but none of the modeling strategies tested could accurately predict the concentration of the acid and base components in the vapor phase.
Journal of Chemical & Engineering Data, Apr 28, 2020
Ionic liquids have the potential to be used for extracting valuable chemicals from raw materials.... more Ionic liquids have the potential to be used for extracting valuable chemicals from raw materials. These processes often involve water, and after extraction, the water or other chemicals must be removed from the ionic liquid, so it can be reused. To help in designing such processes, we present data on the vapor−liquid equilibrium of the system containing protic ionic liquid 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-enium acetate, water, acetic acid, and 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5ene. Earlier studies have only focused on mixtures of water and an ionic liquid with a stoichiometric ratio of the ions. Here, we also investigated mixtures containing an excess of the acid or base component because in real systems with protic ionic liquids, the amount of acid and base in the mixture can vary. We modeled the data using both the ePC-SAFT and NRTL models, and we compared the performance of different modeling strategies. We also experimentally determined the vapor composition for a few of the samples, but none of the modeling strategies tested could accurately predict the concentration of the acid and base components in the vapor phase.
Chemistry teacher international, Mar 1, 2021
Organic electronics has developed rapidly over the past 40 years. In 1977, a seminal discovery wa... more Organic electronics has developed rapidly over the past 40 years. In 1977, a seminal discovery was reported that showed that a polymer known as polyacetylene could conduct electricity as well as metals could. This was a groundbreaking discovery that led to a Nobel Prize in Chemistry in 2000. The polymers that are used in organic electronics have now been widely studied for use in organic solar cells (OSCs), organic field effect transistors (OFETs), printable electronics, flexible electronics, antistatic coatings, actuators, and more recently in bioelectronics. In particular, the utility of organic electronics is seen in the commercial success of using organic electronic materials in organic light-emitting diodes (OLEDs) where OLED displays can be seen in mobile phones and as flat panel displays. In this paper, we provide a tutorial targeting upper secondary students describing how these special classes of polymers function, and how they can be synthesized. The paper further discusses the use of these materials in two applications: organic solar cells and organic lightemitting diodes. The paper ends with a brief discussion about hands-on activities that can be carried out in the upper secondary student science classroom.
Reviews in Analytical Chemistry, 1999
Langmuir, Jan 19, 2017
Owing to their unique properties and unlimited structural combinations, the ubiquitous use of ion... more Owing to their unique properties and unlimited structural combinations, the ubiquitous use of ionic liquids (ILs) is steadily increasing. The objective of the present work is to shed light into the effects of amidinium-and phosphonium-based ILs on phospholipid vesicles using a nanoplasmonic sensing measurement technique. A new and relatively simple method was developed for the immobilization of large unilamellar vesicles on two different hydrophilic surfaces composed of titanium dioxide and silicon nitride nanolayers. Among the pretreatment conditions studied, vesicle attachment on both substrate materials was achieved with HEPES buffer in the presence of sodium hydroxide and calcium chloride. To get an understanding of how ILs interact with intact vesicles or with supported lipid bilayers, the ionic liquids 1,5-diazabicyclo(4.3.0)non-5-enium acetate ([DBNH][OAc]), tributyl(tetradecyl)phosphonium acetate ([P 14444 ][OAc]), and tributylmethylphosphonium acetate ([P 4441 ][OAc]) were introduced into the biomimetic system and the characteristics of their interactions with the immobilized vesicles were determined. Depending on the IL, in situ real-time IL binding and/or phospholipid removal processes were observed. While [DBNH][OAc] did not have any significant effect on the phospholipid vesicles, the strongest and the most significant effect was observed with [P 14444 ][OAc]. The latter caused clear changes in the phospholipid bilayer: the ILs interacted with the bilayers resulting in deformation of the vesicles most probably due to the formation of vesicle-IL aggregates. Only a mild effect was observed when [P 4441 ][OAc], at a very high concentration, was exposed to the intact vesicles. In general these results led to new insights into the effects of ILs on phospholipid vesicles, which are of great importance for the overall understanding of the harmfulness of ILs on biomembranes and biomimicking systems. In addition, the present work highlights the pivotal role of this highly surface-sensitive indirect biosensing technique in scrutinizing and dissecting the integrity and architecture of phospholipid vesicles in the nanoscale range.
Springer eBooks, 2023
An automated on-line isolation and fractionation system including controlling software was develo... more An automated on-line isolation and fractionation system including controlling software was developed for selected nanosized biomacromolecules from human plasma by on-line coupled immunoaffinity chromatography-asymmetric flow field-flow fractionation (IAC-AsFlFFF). The on-line system was versatile, only different monoclonal antibodies, anti-apolipoprotein B-100, anti-CD9, or anti-CD61, were immobilized on monolithic disk columns for isolation of lipoproteins and extracellular vesicles (EVs). The platelet-derived CD61-positive EVs and CD9-positive EVs, isolated by IAC, were further fractionated by AsFlFFF to their sizebased subpopulations (e.g. exomeres and exosomes) for further analysis. Field-emission scanning electron microscope elucidated the morphology of the subpopulations, and 20 free amino acids and glucose in EV subpopulations were identified and quantified in ng/mL range using hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC-MS/MS). The study revealed that there were significant differences between EV origin and size based subpopulations. The on-line coupled IAC-AsFlFFF system was successfully programmed for reliable execution of 10 sequential isolation and fractionation cycles (37-80 min per cycle) with minimal operator involvement, minimal sample losses, and contamination. The relative standard deviations (RSD) between the cycles for human plasma samples were 0.84-6.6%.
Journal of chromatography open, Nov 1, 2021
Journal of Separation Science, Jun 1, 2009
Nonylphenol ethoxylates (NPEOx) are surfactants which are used worldwide and can be transformed i... more Nonylphenol ethoxylates (NPEOx) are surfactants which are used worldwide and can be transformed in the environment by microorganisms to form nonylphenol (NP). Analysis of these compounds was carried out with micellar electrokinetic capillary chromatography (MEKC). Different parameters such as background electrolyte (BGE) solution, pH, type of surfactant, and sample stacking were optimized. The use of CHES (20 mM, pH 9.1) in combination with 50 mM sodium cholate as a surfactant as BGE solution, together with sample stacking using 50 mM NaCl in the sample and an injection time of 20 s, provided the best separation of the compounds studied. The method was applied to the determination of target analytes in two types of sludge water coming from two steps of a wastewater treatment plant. Liquid–liquid extraction was carried out using toluene as solvent, resulting in recoveries around 100% for all studied analytes. The presence of NPEOx was observed in the first step of the sludge water treatment, based on migration time and UV spectra. Identification was confirmed using tandem MS. LOQs of the studied compounds were in the range of 12.7 to 30.8 ng/mL, which is satisfactory for the analysis of real wastewater samples.
MRS Proceedings, 2012
ABSTRACTHierarchically porous silica monoliths were introduced into liquid phase chromatography a... more ABSTRACTHierarchically porous silica monoliths were introduced into liquid phase chromatography at the beginning of the last decade. The high surface area, high void volume and bicontinuous nature of the porosity of the materials are significant advantages over existing chromatographic supports and have resulted in rapid acceptance of these materials into the chromatography market.We report here on the synthesis of 3-D porous silver, cobalt oxide and zinc oxide monoliths, their materials characterization, fabrication as liquid chromatographic columns and initial chromatographic characterization. The, as prepared, columns gave very low back pressure, consistent with the bicontinuous nature of the columns. Cobalt oxide and zinc oxide both demonstrated retention of a number of nitrogen heterocycles, providing the basis for molecular separation.
Capillary electrochromatography (CEC) is an electromigration separation technique that is a hybri... more Capillary electrochromatography (CEC) is an electromigration separation technique that is a hybrid between capillary electrophoresis and liquid chromatography. This chapter covers the basic principles of the methodology including some theoretical aspects and the instrumentation. CEC can be performed either in packed or open-tubular capillary columns, and the packed capillary columns can be further divided in to particle-packed columns and monolithic columns. The latter are slowly attracting more and more attention. The CEC detection techniques are briefly described with special emphasis on on-line CEC mass spectrometric detection. Some general aspects on miniaturized systems are introduced and finally some typical CEC applications are described.