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Thomas Hankemeier - One of the best experts on this subject based on the ideXlab platform.

  • Electroextraction and electromembrane extraction advances in hyphenation to analytical techniques
    Electrophoresis, 2016
    Co-Authors: Amar Oedit, Thomas Hankemeier, Rawi Ramautar, Petrus W Lindenburg
    Abstract:

    Electroextraction (EE) and electromembrane extraction (EME) are sample preparation techniques that both require an electric field that is applied over a liquid-liquid system, which enables the migration of charged analytes. Furthermore, both techniques are often used to pre-concentrate analytes prior to analysis. In this review an overview is provided of the body of literature spanning April 2012-November 2015 concerning EE and EME, focused on hyphenation to analytical techniques. First, the theoretical aspects of concentration enhancement in EE and EME are discussed to explain extraction recovery and enrichment factor. Next, overviews are provided of the techniques based on their hyphenation to LC, GC, CE, and direct detection. These overviews cover the compounds and matrices, experimental aspects (i.e. donor volume, acceptor volume, extraction time, extraction voltage, and separation time) and the analytical aspects (i.e. limit of detection, enrichment factor, and extraction recovery). Techniques that were either hyphenated online to analytical techniques or show high potential with respect to online hyphenation are highlighted. Finally, the potential future directions of EE and EME are discussed.

  • three phase Electroextraction a new online sample purification and enrichment method for bioanalysis
    Analytical Chemistry, 2013
    Co-Authors: Robertjan Raterink, Petrus W Lindenburg, Rob J Vreeken, Thomas Hankemeier
    Abstract:

    The migration and at the same time enrichment of analytes from a liquid aqueous sample donor phase through an immiscible organic solvent layer acting as a filter phase into a liquid aqueous acceptor phase is enabled by the application of an electric field between the donor and acceptor phase. The organic filter phase acts as a purification filter, which prevents, for example, proteins from migrating into the acceptor phase. Moreover, the composition of the organic filter phase influences the selectivity of the extraction. We show that analytes can be rapidly enriched from a 50 μL donor phase at the bottom of a sample vial, via an immiscible organic filter phase, into a 2 μL acceptor phase which consists of a droplet that is hanging from a (conductive) pipet tip in the organic filter phase. Acylcarnitines spiked to human plasma as a donor phase were extracted reproducibly with good linearity and a 10-fold improved limit of detection and, importantly, resulted in a stable, protein-free nanoelectrospray signal. Finally, a proof of principle toward the online integration in an automated nanoelectrospray-direct infusion-mass spectrometry platform has been realized. This makes 3-phase Electroextraction (3-phase EE) a novel sample purification and enrichment method, with straightforward online integration possibility. We envision that 3-phase EE will enable new possibilities using electrokinetic sample pretreatment for fully automated, high-throughput bioanalysis purposes.

  • feasibility of Electroextraction as versatile sample preconcentration for fast and sensitive analysis of urine metabolites demonstrated on acylcarnitines
    Electrophoresis, 2012
    Co-Authors: Petrus W Lindenburg, U.r. Tjaden, Jan Van Der Greef, Thomas Hankemeier
    Abstract:

    In this work, we demonstrate the applicability of Electroextraction (EE) to urine metabolites. To investigate which urine metabolite classes are susceptible to EE, off-line EE experiments were carried out with a prototype device, in which urine metabolites were electroextracted from ethyl acetate into water. The obtained extracts were examined with direct infusion MS and the results demonstrated that several compound classes could be extracted, amongst which amino acids and acylcarnitines. Acylcarnitines were selected for evaluation of the performance of EE. For this, the EE setup was adapted to capillary EE (cEE) to be able to analyze large urine sample series, and it was coupled online to LC-MS. cEE-LC-MS of acylcarnitines was optimized and characterized. The recovery, linearity, repeatability, and detection limit of the cEE-LC-MS method was good to excellent. To demonstrate the versatility of EE for sample preparation in analytical procedures, extracts were injected into a CZE-MS system, resulting in detection of the acylcarnitines along with more than 100 presumed metabolite peaks. The results presented here indicate that EE can be used as a fast sample preconcentration technique of low abundant urine metabolites, in combination with both LC and CZE.

  • on line large volume Electroextraction coupled to liquid chromatography mass spectrometry to improve detection of peptides
    Journal of Chromatography A, 2012
    Co-Authors: Petrus W Lindenburg, U.r. Tjaden, F Alexander W Tempels, Jan Van Der Greef, Thomas Hankemeier
    Abstract:

    Electroextraction (EE) takes place in a two-phase liquid-liquid system, consisting of an aqueous and an organic phase, where an applied electric field causes ions to be extracted from one phase into the other, to be concentrated close after the liquid-liquid interface. The extraction takes place in a wide-bore capillary that is connected to a 2-way 10-port switching valve, which serves to couple capillary EE (cEE) with LC-MS. In this set-up, volumes as high as 100 μL can be extracted, which is a ten times larger volume than has been reported, earlier. After a feasibility study using the cationic purple dye crystal violet, the method was coupled to LC-MS and large volume cEE of several model peptides was optimized. The cEE-LC-MS method had good repeatability, good linearity and LODs between 0.5 and 10. nM. The whole procedure was automated and could be used routinely. Finally, the method was applied to plasma analysis and calibration curves of the relevant plasma peptides angiotensin 1 and 2 as well as the fragment angiotensin 2 (3-8) showed good linearity and repeatability; LOD values were 10-50. nM. Analysis of unspiked plasma resulted in 60 putative endogenous peptides, underlining the great potential of EE as on-line sample concentrating technique. On-line large volume cEE-LC-MS allows for enrichment, separation and detection of plasma peptides from large sample volumes, minimizes sample handling and can be an important step in full automation of analytical procedures. © 2012 Elsevier B.V. Chemicals/CAS: angiotensin I, 9041-90-1; angiotensin II, 11128-99-7; crystal violet, 467-63-0, 548-62-9

  • online capillary liquid liquid Electroextraction of peptides as fast pre concentration prior to lc ms
    Electrophoresis, 2010
    Co-Authors: Petrus W Lindenburg, U.r. Tjaden, Remco Seitzinger, F Alexander W Tempels, Jan Van Der Greef, Thomas Hankemeier
    Abstract:

    In this research paper, we show that capillary Electroextraction (cEE) is capable of fast online peptide concentration and that it can be coupled online to LC-MS to result in a fast and sensitive method. Electroextraction takes place when an electrical field is applied in a two-phase liquid-liquid system. Sample molecules in the organic phase migrate very fast into the aqueous phase and are concentrated in a small zone. In this work, cEE of peptides is developed and coupled online to LC-MS via a switching valve. Comparison of 10 min of cEE-LC-MS with a normal LC-MS injection showed more than 100-fold increased peak heights. Of five model peptides, good calibration curves in the range of 0.05-5 μmol/L were obtained. The linearity was good (R2 values between 0.984 and 0.996) and RSD between 5% at the highest to 25% at the lowest concentration (n=3). The LOD of bradykinin, angiotensin I-converting enzyme inhibitor and angiotensin I was in the low nmol/L range. Analysis of a tryptic digest of eight model proteins resulted in more than 170 peptides, without bias for pI or hydrophilicity. Urine analysis is demonstrated, resulting in an LOD around 0.04 μmol/L urine for tryptic cytochrome C peptides spiked to urine and an increase of 42% in the number of chromatographic peaks compared with the conventional LC-MS. In summary, cEE-LC-MS is a fast electrophoresis-driven sample preconcentration technique that is quantitative, able to extract a wide peptide range and applicable to bioanalysis. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Petrus W Lindenburg - One of the best experts on this subject based on the ideXlab platform.

  • Electroextraction and electromembrane extraction advances in hyphenation to analytical techniques
    Electrophoresis, 2016
    Co-Authors: Amar Oedit, Thomas Hankemeier, Rawi Ramautar, Petrus W Lindenburg
    Abstract:

    Electroextraction (EE) and electromembrane extraction (EME) are sample preparation techniques that both require an electric field that is applied over a liquid-liquid system, which enables the migration of charged analytes. Furthermore, both techniques are often used to pre-concentrate analytes prior to analysis. In this review an overview is provided of the body of literature spanning April 2012-November 2015 concerning EE and EME, focused on hyphenation to analytical techniques. First, the theoretical aspects of concentration enhancement in EE and EME are discussed to explain extraction recovery and enrichment factor. Next, overviews are provided of the techniques based on their hyphenation to LC, GC, CE, and direct detection. These overviews cover the compounds and matrices, experimental aspects (i.e. donor volume, acceptor volume, extraction time, extraction voltage, and separation time) and the analytical aspects (i.e. limit of detection, enrichment factor, and extraction recovery). Techniques that were either hyphenated online to analytical techniques or show high potential with respect to online hyphenation are highlighted. Finally, the potential future directions of EE and EME are discussed.

  • three phase Electroextraction a new online sample purification and enrichment method for bioanalysis
    Analytical Chemistry, 2013
    Co-Authors: Robertjan Raterink, Petrus W Lindenburg, Rob J Vreeken, Thomas Hankemeier
    Abstract:

    The migration and at the same time enrichment of analytes from a liquid aqueous sample donor phase through an immiscible organic solvent layer acting as a filter phase into a liquid aqueous acceptor phase is enabled by the application of an electric field between the donor and acceptor phase. The organic filter phase acts as a purification filter, which prevents, for example, proteins from migrating into the acceptor phase. Moreover, the composition of the organic filter phase influences the selectivity of the extraction. We show that analytes can be rapidly enriched from a 50 μL donor phase at the bottom of a sample vial, via an immiscible organic filter phase, into a 2 μL acceptor phase which consists of a droplet that is hanging from a (conductive) pipet tip in the organic filter phase. Acylcarnitines spiked to human plasma as a donor phase were extracted reproducibly with good linearity and a 10-fold improved limit of detection and, importantly, resulted in a stable, protein-free nanoelectrospray signal. Finally, a proof of principle toward the online integration in an automated nanoelectrospray-direct infusion-mass spectrometry platform has been realized. This makes 3-phase Electroextraction (3-phase EE) a novel sample purification and enrichment method, with straightforward online integration possibility. We envision that 3-phase EE will enable new possibilities using electrokinetic sample pretreatment for fully automated, high-throughput bioanalysis purposes.

  • feasibility of Electroextraction as versatile sample preconcentration for fast and sensitive analysis of urine metabolites demonstrated on acylcarnitines
    Electrophoresis, 2012
    Co-Authors: Petrus W Lindenburg, U.r. Tjaden, Jan Van Der Greef, Thomas Hankemeier
    Abstract:

    In this work, we demonstrate the applicability of Electroextraction (EE) to urine metabolites. To investigate which urine metabolite classes are susceptible to EE, off-line EE experiments were carried out with a prototype device, in which urine metabolites were electroextracted from ethyl acetate into water. The obtained extracts were examined with direct infusion MS and the results demonstrated that several compound classes could be extracted, amongst which amino acids and acylcarnitines. Acylcarnitines were selected for evaluation of the performance of EE. For this, the EE setup was adapted to capillary EE (cEE) to be able to analyze large urine sample series, and it was coupled online to LC-MS. cEE-LC-MS of acylcarnitines was optimized and characterized. The recovery, linearity, repeatability, and detection limit of the cEE-LC-MS method was good to excellent. To demonstrate the versatility of EE for sample preparation in analytical procedures, extracts were injected into a CZE-MS system, resulting in detection of the acylcarnitines along with more than 100 presumed metabolite peaks. The results presented here indicate that EE can be used as a fast sample preconcentration technique of low abundant urine metabolites, in combination with both LC and CZE.

  • on line large volume Electroextraction coupled to liquid chromatography mass spectrometry to improve detection of peptides
    Journal of Chromatography A, 2012
    Co-Authors: Petrus W Lindenburg, U.r. Tjaden, F Alexander W Tempels, Jan Van Der Greef, Thomas Hankemeier
    Abstract:

    Electroextraction (EE) takes place in a two-phase liquid-liquid system, consisting of an aqueous and an organic phase, where an applied electric field causes ions to be extracted from one phase into the other, to be concentrated close after the liquid-liquid interface. The extraction takes place in a wide-bore capillary that is connected to a 2-way 10-port switching valve, which serves to couple capillary EE (cEE) with LC-MS. In this set-up, volumes as high as 100 μL can be extracted, which is a ten times larger volume than has been reported, earlier. After a feasibility study using the cationic purple dye crystal violet, the method was coupled to LC-MS and large volume cEE of several model peptides was optimized. The cEE-LC-MS method had good repeatability, good linearity and LODs between 0.5 and 10. nM. The whole procedure was automated and could be used routinely. Finally, the method was applied to plasma analysis and calibration curves of the relevant plasma peptides angiotensin 1 and 2 as well as the fragment angiotensin 2 (3-8) showed good linearity and repeatability; LOD values were 10-50. nM. Analysis of unspiked plasma resulted in 60 putative endogenous peptides, underlining the great potential of EE as on-line sample concentrating technique. On-line large volume cEE-LC-MS allows for enrichment, separation and detection of plasma peptides from large sample volumes, minimizes sample handling and can be an important step in full automation of analytical procedures. © 2012 Elsevier B.V. Chemicals/CAS: angiotensin I, 9041-90-1; angiotensin II, 11128-99-7; crystal violet, 467-63-0, 548-62-9

  • online capillary liquid liquid Electroextraction of peptides as fast pre concentration prior to lc ms
    Electrophoresis, 2010
    Co-Authors: Petrus W Lindenburg, U.r. Tjaden, Remco Seitzinger, F Alexander W Tempels, Jan Van Der Greef, Thomas Hankemeier
    Abstract:

    In this research paper, we show that capillary Electroextraction (cEE) is capable of fast online peptide concentration and that it can be coupled online to LC-MS to result in a fast and sensitive method. Electroextraction takes place when an electrical field is applied in a two-phase liquid-liquid system. Sample molecules in the organic phase migrate very fast into the aqueous phase and are concentrated in a small zone. In this work, cEE of peptides is developed and coupled online to LC-MS via a switching valve. Comparison of 10 min of cEE-LC-MS with a normal LC-MS injection showed more than 100-fold increased peak heights. Of five model peptides, good calibration curves in the range of 0.05-5 μmol/L were obtained. The linearity was good (R2 values between 0.984 and 0.996) and RSD between 5% at the highest to 25% at the lowest concentration (n=3). The LOD of bradykinin, angiotensin I-converting enzyme inhibitor and angiotensin I was in the low nmol/L range. Analysis of a tryptic digest of eight model proteins resulted in more than 170 peptides, without bias for pI or hydrophilicity. Urine analysis is demonstrated, resulting in an LOD around 0.04 μmol/L urine for tryptic cytochrome C peptides spiked to urine and an increase of 42% in the number of chromatographic peaks compared with the conventional LC-MS. In summary, cEE-LC-MS is a fast electrophoresis-driven sample preconcentration technique that is quantitative, able to extract a wide peptide range and applicable to bioanalysis. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

J. Teissié - One of the best experts on this subject based on the ideXlab platform.

  • Optimization of protein Electroextraction from microalgae by a flow process
    Bioelectrochemistry, 2015
    Co-Authors: M. Coustets, Vanessa Joubert-durigneux, Josiane Hérault, Benoît Schoefs, Vincent Blanckaert, Jean-pierre Garnier, J. Teissié
    Abstract:

    Classical methods, used for large scale treatments such as mechanical or chemical extractions, affect the integrity of extracted cytosolic protein by releasing proteases contained in vacuoles. Our previous experiments on flow processes Electroextraction on yeasts proved that pulsed electric field technology allows preserving the integrity of released cytosolic proteins, by not affecting vacuole membranes. Furthermore, large cell culture volumes are easily treated by the flow technology. Based on this previous knowledge, we developed a new protocol in order to electro-extract total cytoplasmic proteins from microalgae (Nannochloropsis salina, Chlorella vulgaris and Haematococcus pluvialis). Given that induction of electropermeabilization is under the control of target cell size, as the mean diameter for N. salina is only 2.5 μm, we used repetitive 2 ms long pulses of alternating polarities with stronger field strengths than previously described for yeasts. The electric treatment was followed by a 24 h incubation period in a salty buffer. The amount of total protein release was observed by a classical Bradford assay. A more accurate evaluation of protein release was obtained by SDS-PAGE. Similar results were obtained with C. vulgaris and H. pluvialis under milder electrical conditions as expected from their larger size.

  • Flow Process for Electroextraction of Total Proteins from Microalgae
    The Journal of Membrane Biology, 2013
    Co-Authors: M. Coustets, N. Al-karablieh, C. Thomsen, J. Teissié
    Abstract:

    Classical methods for protein extraction from microorganisms, used for large-scale treatments such as mechanical or chemical processes, affect the integrity of extracted cytosolic protein by releasing proteases contained in vacuoles. Our previous experiments on flow-process yeast Electroextraction proved that pulsed electric field technology allows us to preserve the integrity of released cytosolic proteins by keeping intact vacuole membranes. Furthermore, large volumes are easily treated by the flow technology. Based on this previous knowledge, we developed a new protocol in order to electroextract total cytoplasmic proteins from microalgae ( Nannochloropsis salina and Chlorella vulgaris ). Given that induction of electropermeabilization is under the control of the target cell size, as the mean diameter for N. salina is only 2.5 μm, we used repetitive 2-ms-long pulses of alternating polarities with stronger field strengths than previously described for yeasts. The electric treatment was followed by a 24-h incubation period in a salty buffer. The amount of total protein released was evaluated by a classical Bradford assay. A more accurate evaluation of protein release was obtained by SDS-PAGE. Similar results were obtained with C. vulgaris under milder electrical conditions, as expected from their larger size. This innovative technology designed in our group should become familiar in the field of microalgae biotechnology.

  • flow process for Electroextraction of intracellular enzymes from the fission yeast schizosaccharomyces pombe
    Biotechnology Letters, 2004
    Co-Authors: Valentina Ganeva, Bojidar Galutzov, J. Teissié
    Abstract:

    Flow treatment of the yeast, Schizosaccharomyces pombe, with high intensity electric field pulses released intracellular enzymes such as glyceraldehyde-3-phosphate dehydrogenase and phosphoglycerate kinase. Over 70% of the total activity was liberated within 4 h after pulse application. The optimal field intensities were considerably higher than that needed for irreversible plasma membrane permeabilization.

  • high yield Electroextraction of proteins from yeast by a flow process
    Analytical Biochemistry, 2003
    Co-Authors: Valentina Ganeva, Bojidar Galutzov, J. Teissié
    Abstract:

    Abstract High yields of intracellular enzymes from yeast can be obtained by application of a series of electric field pulses with a flow process. Up to 80–90% of the total activity can be liberated without any further or previous treatment of cells. The method is based on electroinduced changes in the cell envelope leading to a leakage of part of the intracellular proteins without formation of debris and permits treatment of large volumes. Field parameters require a limited electrical power. Treatment of at least 20% wet weight suspensions is possible. The optimal field conditions must be adjusted to the suspension concentration. Maximal yield is obtained within 4 h at 30 °C for enzymes from Saccharomyces cerevisiae such as hexokinase, 3-phosphoglycerate kinase, and glyceraldehyde-3-phosphate dehydrogenase. The extraction of β- d -galactosidase from Kluyveromyces lactis lasts 10 h but can be accelerated by adding dithiothreitol in the postpulse medium. The specific activities of the electroextracted enzymes are higher than those obtained by mechanical disintegration or enzymatic lysis.

Jacqueline Sandeaux - One of the best experts on this subject based on the ideXlab platform.

  • Electroextraction of heavy metals from diluted solutions by a process combining ion-exchange resins and membranes
    Separation and Purification Technology, 2005
    Co-Authors: Abdelaziz Smara, Rachid Delimi, Christiane Poinsignon, Jacqueline Sandeaux
    Abstract:

    The Electroextraction of heavy metals (Pb2+, Cu2+, Zn2+ and Cd2+) from diluted solutions was achieved by continuous electropermutation combining ion-exchange resins and membranes. Under an applied current, the metallic cations fixed onto the resin are substituted by protons coming from the anodic compartment, and are transferred into a receiver compartment, at the cathodic side, where they are concentrated. Electroextraction operations were performed under various experimental conditions of current density (2–7 A m–2), flow rate (0.09–0.9 dm3 h–1), cation concentration (40–400 mg dm–3) and nature of regenerating acid solutions (HNO3, HCl, H2SO4). Despite the resins were loaded with the metallic cations before introducing in the feed compartment of the cell, high levels of removal (up to 99%) were achieved. High mass transfer was obtained leading to a concentration factor of about five in the receiver.

  • Electroextraction of pb2 ions from diluted solutions by a process combining ion exchange textiles and membranes
    Desalination, 1998
    Co-Authors: K Basta, A Aliane, A Lounis, Roger Sandeaux, Jacqueline Sandeaux, Claude Gavach
    Abstract:

    Abstract The extraction of Pb2+ ions from diluted solutions was achieved using a hybrid process combining cation exchange textiles, ion-exchange membranes and electric current. Two methods were investigated: an Electroextraction process in two steps where the fixation of Pb2+ ions was followed by electroregeneration of the cation-exchange textiles; the second one a continuous Electroextraction process where the ion exchange and regeneration take place simultaneously. For these Electroextraction processes, the cation-exchange textile is introduced into an electrodialysis cell and compressed between two cation-exchange membranes. Under an applied current, the Pb2+ ions are substituted by regenerating ions coming from the anodic compartment and are transferred into a receiver compartment at the cathodic side where they are concentrated. Cation-exchange textiles having strong or weak acid functional groups, sulfonic (SCET) and carboxylic (CCET), respectively, were used. Different regenerating ions, H+, Na+, K+ and NH4+ were investigated under various current densities. Electroregeneration ratios between 85% and 100% were obtained with sulfonic and carboxylic textiles previously loaded with Pb2+ ions. In the continuous Electroextraction, removal efficiencies higher than 95% were obtained with a 10 ppm Pb2+ feed solution giving an outlet concentration of less than 1 ppm. The efficiency of the two textiles was compared in terms of mass transfer and energy consumption.

U.r. Tjaden - One of the best experts on this subject based on the ideXlab platform.

  • feasibility of Electroextraction as versatile sample preconcentration for fast and sensitive analysis of urine metabolites demonstrated on acylcarnitines
    Electrophoresis, 2012
    Co-Authors: Petrus W Lindenburg, U.r. Tjaden, Jan Van Der Greef, Thomas Hankemeier
    Abstract:

    In this work, we demonstrate the applicability of Electroextraction (EE) to urine metabolites. To investigate which urine metabolite classes are susceptible to EE, off-line EE experiments were carried out with a prototype device, in which urine metabolites were electroextracted from ethyl acetate into water. The obtained extracts were examined with direct infusion MS and the results demonstrated that several compound classes could be extracted, amongst which amino acids and acylcarnitines. Acylcarnitines were selected for evaluation of the performance of EE. For this, the EE setup was adapted to capillary EE (cEE) to be able to analyze large urine sample series, and it was coupled online to LC-MS. cEE-LC-MS of acylcarnitines was optimized and characterized. The recovery, linearity, repeatability, and detection limit of the cEE-LC-MS method was good to excellent. To demonstrate the versatility of EE for sample preparation in analytical procedures, extracts were injected into a CZE-MS system, resulting in detection of the acylcarnitines along with more than 100 presumed metabolite peaks. The results presented here indicate that EE can be used as a fast sample preconcentration technique of low abundant urine metabolites, in combination with both LC and CZE.

  • on line large volume Electroextraction coupled to liquid chromatography mass spectrometry to improve detection of peptides
    Journal of Chromatography A, 2012
    Co-Authors: Petrus W Lindenburg, U.r. Tjaden, F Alexander W Tempels, Jan Van Der Greef, Thomas Hankemeier
    Abstract:

    Electroextraction (EE) takes place in a two-phase liquid-liquid system, consisting of an aqueous and an organic phase, where an applied electric field causes ions to be extracted from one phase into the other, to be concentrated close after the liquid-liquid interface. The extraction takes place in a wide-bore capillary that is connected to a 2-way 10-port switching valve, which serves to couple capillary EE (cEE) with LC-MS. In this set-up, volumes as high as 100 μL can be extracted, which is a ten times larger volume than has been reported, earlier. After a feasibility study using the cationic purple dye crystal violet, the method was coupled to LC-MS and large volume cEE of several model peptides was optimized. The cEE-LC-MS method had good repeatability, good linearity and LODs between 0.5 and 10. nM. The whole procedure was automated and could be used routinely. Finally, the method was applied to plasma analysis and calibration curves of the relevant plasma peptides angiotensin 1 and 2 as well as the fragment angiotensin 2 (3-8) showed good linearity and repeatability; LOD values were 10-50. nM. Analysis of unspiked plasma resulted in 60 putative endogenous peptides, underlining the great potential of EE as on-line sample concentrating technique. On-line large volume cEE-LC-MS allows for enrichment, separation and detection of plasma peptides from large sample volumes, minimizes sample handling and can be an important step in full automation of analytical procedures. © 2012 Elsevier B.V. Chemicals/CAS: angiotensin I, 9041-90-1; angiotensin II, 11128-99-7; crystal violet, 467-63-0, 548-62-9

  • online capillary liquid liquid Electroextraction of peptides as fast pre concentration prior to lc ms
    Electrophoresis, 2010
    Co-Authors: Petrus W Lindenburg, U.r. Tjaden, Remco Seitzinger, F Alexander W Tempels, Jan Van Der Greef, Thomas Hankemeier
    Abstract:

    In this research paper, we show that capillary Electroextraction (cEE) is capable of fast online peptide concentration and that it can be coupled online to LC-MS to result in a fast and sensitive method. Electroextraction takes place when an electrical field is applied in a two-phase liquid-liquid system. Sample molecules in the organic phase migrate very fast into the aqueous phase and are concentrated in a small zone. In this work, cEE of peptides is developed and coupled online to LC-MS via a switching valve. Comparison of 10 min of cEE-LC-MS with a normal LC-MS injection showed more than 100-fold increased peak heights. Of five model peptides, good calibration curves in the range of 0.05-5 μmol/L were obtained. The linearity was good (R2 values between 0.984 and 0.996) and RSD between 5% at the highest to 25% at the lowest concentration (n=3). The LOD of bradykinin, angiotensin I-converting enzyme inhibitor and angiotensin I was in the low nmol/L range. Analysis of a tryptic digest of eight model proteins resulted in more than 170 peptides, without bias for pI or hydrophilicity. Urine analysis is demonstrated, resulting in an LOD around 0.04 μmol/L urine for tryptic cytochrome C peptides spiked to urine and an increase of 42% in the number of chromatographic peaks compared with the conventional LC-MS. In summary, cEE-LC-MS is a fast electrophoresis-driven sample preconcentration technique that is quantitative, able to extract a wide peptide range and applicable to bioanalysis. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  • Development of a needle device for on-line Electroextraction-liquid chromatography
    Journal of Chromatography A, 1996
    Co-Authors: E. Van Der Vlis, M. Mazereeuw, U.r. Tjaden, H. Irth, J. Van Der Greef
    Abstract:

    The development of a needle device enabling on-line Electroextraction coupled to high-performance liquid chromatography in an autosampler is described. This Electroextraction needle meets all the demands set to automated liquid handling and can fully replace the conventional autosampler needle. In addition, the system has been fully automated, and can be used as an interfacing technique between solid-phase extraction and liquid chromatography. A detailed description of the Electroextraction needle hardware, as well as some typical examples of its use in on-line Electroextraction-liquid chromatography are presented.

  • combined liquid liquid Electroextraction isotachophoresis for loadability enhancement in capillary zone electrophoresis mass spectrometry
    Journal of Chromatography A, 1995
    Co-Authors: E. Van Der Vlis, M. Mazereeuw, U.r. Tjaden, H. Irth, J. Van Der Greef
    Abstract:

    Abstract Combined liquid-liquid Electroextraction (EE) and isotachophoresis (ITP) as a fast on-line focusing step in capillary zone electrophoresis (CZE) prior to electrospray mass spectrometric (ESP-MS) detection is described. Very high electric field strengths can be applied owing to the low conductivity of the organic phase, which results in high migration rates. Liquid-liquid Electroextraction enables the fast extraction of analyte ions into a small buffer volume, whereas ITP is used to focus the analytes away from the liquid-liquid interface. As a result, ITP starts with a small sample volume containing the extracted ions. After reaching the steady state within several minutes, CZE separation follows. Clenbuterol, salbutamol, terbutaline and fenoterol were used as model compounds. Concentration detection limits of pure solutions down to 2·10 −9 mol/l for clenbuterol, salbutamol and terbutaline, and 5·10 −9 mol/l for fenoterol have been achieved using on-line EE-ITP-CZE-ESP-MS.