Titel Deelnemers "Korte inhoud" "Making high salt concentrations for optimal chromatography compatible with electrospray ionization mass spectrometry using an ion exchange membrane suppressor: Analysis of biomarkers for transporter protein inhibition as a case study" "Daniel Meston" "This study reports on the potential of using ion-exchange suppressor technology in liquid chromatography—electrospray ionization mass spectrometry workflows. The aim was to use high salt concentrations to improve separation performance, while overcoming the resulting significant ion suppression during electrospray ionization. As a case study, we apply suppressor technology to the hydrophilic interaction liquid chromatography separation and detection of taurine and glycochenodeoxycholate sulfate, endogenous biomarkers for organic anion transporter protein inhibition. The desired chromatographic selectivity was achieved applying 100 mM ion-pairing agent, while competing ions negatively affecting MS sensitivity were actively removed post-column from the solvent via a charged partially permeable membrane and replaced with protons, resulting in an up to 10-fold increase in detection sensitivity." "Comparison of microsublimation and ion exchange chromatography for boron isolation preceding its isotopic analysis via multi-collector ICP-MS" "Veerle Devulder, Philippe Claeys, Patrick Degryse" "© 2014 the Partner Organisations. Boron isotopic analysis is of interest in many research fields and for a large variety of sample types. Accurate and precise determination of boron isotope ratios using multi-collector ICP-mass spectrometry or thermal ionization mass spectrometry requires isolation of the target element prior to isotopic analysis, which is accomplished using either ion exchange chromatography or microsublimation. This study systematically compares the two methods in terms of B recovery, procedural blank, matrix removal efficiency, accuracy and precision of the resulting δ11B values as measured using multi-collector ICP-mass spectrometry, as well as labor intensiveness and costs. For this purpose, four types of sample matrices, i.e. 20 g L-1Ca aqueous solution, seawater, digests of spinach (100 g L-1) and silicate glass (10 g L-1), were stripped from their original B content and spiked with B of known isotopic composition and were then subjected to both sample preparation methods and subsequent isotopic analysis of the purified B fraction via multi-collector ICP-mass spectrometry. For both methods, the highest (quantitative) B recoveries were obtained for Ca-rich aqueous solution and seawater. For spinach, accurate δ11B values were obtained after ion exchange chromatography. However, microsublimation was plagued by isotope fractionation, resulting in large offsets (∼8‰) between the experimental results and the corresponding reference values. For glass, B recovery was incomplete, nevertheless the absence of fractionation rendered both sample preparation methods suitable. Overall, in the absence of isotope fractionation, microsublimation appears advantageous in terms of procedural blanks, matrix removal efficiency, precision (2 s) on δ11B values, labor intensiveness and costs." "Comparison of microsublimation and ion exchange chromatography for boron isolation preceding its isotopic analysis via multi-collector ICP-MS" "Geen naam beschikbaar, Geen naam beschikbaar" "Boron isotopic analysis is of interest in many research fields and for a large variety of sample types. Accurate and precise determination of boron isotope ratios using multi-collector ICP - mass spectrometry or thermal ionization mass spectrometry requires isolation of the target element prior to isotopic analysis, which is accomplished using either ion exchange chromatography or microsublimation. This study systematically compares the two methods in terms of B recovery, procedural blank, matrix removal efficiency, accuracy and precision of the resulting delta 11B values as measured using multi-collector ICP - mass spectrometry, as well as labor intensiveness and costs." "Microfluidic membrane suppressor module design and evaluation for capillary ion chromatography" "Sam Wouters, Cees Bruggink, Yury Agroskin, Christopher Pohl, Sebastiaan Eeltink" "A microfluidic ion-suppression module for use in ion-exchange chromatography has been developedand evaluated. The device consists of an ion-exchange membrane clamped between two polymer chipsfeaturing a 200 × 100 µm (width × depth) eluent channel (l = 60 mm), and a 300 × 150 µm regenerantchannel (60 mm), respectively. The suppression efficacy using a Nafion membrane was compared withthat of a styrene-sulfonate grafted fluorinated ethylene propylene (FEP) membrane. The latter was foundto outperform Nafion in terms of lowest attainable background signal (suppression efficacy) and dynamicsuppression range. Increasing the suppressor temperature or the sulfuric acid regenerant concentrationled to an extension of the operational suppression range, this however at the cost of an increased back-ground signal due to enhanced diffusion, inducing sulfate bleed. Under optimized operating conditions,the microfluidic suppressor provided a dynamic capacity of 0.35 µEq./min, being compatible with gradi-ent separations applying up to 70 mM KOH in combination with 400 µm i.d. capillary columns operatedat the optimal flow velocity. The applicability of the miniaturized suppressor is demonstrated for bothisocratic and gradient separations of mixtures of inorganic anions. Band-broadening characteristics ofthe suppressor were optimized with respect to a commercial capillary hollow-fiber suppressor, yieldingcomparable overall system efficiency, e.g., 8500 plates for nitrate recorded on a 150 mm long capillarycolumn. A second chip device was also constructed, featuring suppression at both sides of the eluent flowpath. This double-sided suppressor allowed to increase sample throughput and operate at eluent flowrates of 10 µL/min, while maintaining efficient suppression characteristics." "Ultra-High-Pressure Ion Chromatography with Suppressed Conductivity Detection at 70 MPa Using Columns Packed with 2.5 μm Anion-Exchange Particles" "Sam Wouters, José Luís Dores-Sousa, Christopher A. Pohl, Sebastiaan Eeltink" "The use of ultrahigh pressures in combination with columns packed with 2.5 μm microporous and supermacroporous (perfusive) stationary phase particles coated with nanobeads has been successfully explored in ion chromatography with online eluent generation and suppressed conductivity detection. Isocratic separations of inorganic anions and organic acids yielding reduced plate heights as low as 2.1 were achieved, corresponding to efficiencies up to 190000 plates/m, using an optimized system configuration with respect to injection parameters, considering volume and mass loadability, and extra-column dispersion. Viscous-heating effects have been assessed for PEEK-lined stainless steel columns operated at 70 MPa, and effects of thermal gradients on separation efficiency and retention are demonstrated. Whereas the PEEK-lined column hardware acts to some extent as an insulator, a 10% increase in plate number could be obtained when applying a still-air column oven configuration. In the forced-air mode, an increase in retention was observed for polyvalent ions. Finally, the kinetic performance limits of ultrahigh-pressure ion chromatography applying 2.5 μm particle-packed columns operated at 70 MPa were compared to conventional ion-chromatography technology using columns packed with 4 μm particles operated at a maximum pressure of 35 MPa. Downscaling the particle size and increasing the operating pressure led to a maximum time gain with a factor of 3.4, without compromising separation efficiency (N = 10000)." "Determination of inorganic ions and carbohydrates in cardioplegia and nephroplegia solutions by ion chromatography" "Ann Van Schepdael, Erwin Adams" "In this study, methods for analyzing inorganic ions and carbohydrates in cardioplegia and nephroplegia solutions were developed and validated using ion chromatography with both conductivity and pulsed amperometric detection. The inorganic ions such as sodium, potassium, and calcium were separated by a cation-exchange column with 27 mM methanesulfonic acid as mobile phase at 0.5 mL/min. The anion (chloride) and carbohydrates (mannitol and glucose) were analyzed by an anion-exchange column using a mobile phase of 20 mM sodium hydroxide at 1.0 mL/min. The methods showed a high sensitivity for all analytes, with quantification limits from 0.0002 to 0.06 mg/L. Good linearities between the peak areas and concentrations were found for all analytes within the selected concentration range (R2  > 0.999). Relative standard deviation values for repeatability and interday precision were 0.1%-1.0% and 0.7%-1.6%, respectively. The accuracy was validated by determining the percentage recovery, which was between 98.0% and 101.3% for all analytes, indicating good accuracy of the methods. The robustness was verified by using an experimental design. Finally, real samples were analyzed to determine the content of the analytes. All assay values were between 96.8% and 102.5%." "High-pressure ion chromatography in capillary columns and microfluidic chips" "Bert Wouters, Hamed Eghbali" "Similar like in high-performance liquid chromatography, ion chromatography (IC) has witnessed a trend toward the use of smaller particle packing materials to increase the separation performance. Without compromising the column length, the use of smaller particles leads to higher operating pressure, since the pressure drop is inversely proportional to the square of the particle diameter. To withstand the higher operating pressures and to improve the solvent compatibility the crosslink density of the polymer beads has been increased from 5% to > 50% for today's particles.To meet the demand for analyzing minute amounts of sample there is also strong interest in miniaturization of column technology. Additional benefits of using smaller column I.D.'s are the increased detection sensitivity, and better compatibility with electrospray-ionization mass spectrometry (especially when using aqueous mobile-phases). This has now resulted in the development of capillary IC columns formats and high-pressure capillary systems that are compatible with alkaline mobile-phase.The present contribution discusses the IC performance limits that can be achieved with capillary columns packed with 4 and 7 µm polymer anion-exchange beads, respectively. When operating in the C-term region of the Van Deemter curve a 26% increase in efficiency and maximum time gain of 45% could be established employing 4 µm packed columns and increasing the operating pressure from 3000 to 5000 psi. In addition, the effects of column temperatures up to 80°C on kinetic performance limits and selectivity are discussed for mono-, di-, and trivalent anions. Finally, a the design of a prototype microfluidic chip for IC will be discussed. Different channel layouts were created using a precision micro-milling robot instrument allowing the engineering of channel diameters of 100 µm I.D. and larger. The possibilities to packed chips with polymer IC bead and the in-situ polymerization of monolithic stationary phases are discussed." "Isolation of lanthanides from spent nuclear fuel by means of high performance ion chromatography (HPIC) prior to mass spectrometric analysis" "Jakob Bussé, Thomas Cardinaels" "Pure and complete fractions of neodymium, samarium, europium, gadolinium and dysprosium were isolated by means of high performance ion chromatogra- phy, using a cation exchange column and gradient elution with alpha-hydroxyisobutyric acid solutions (a-HIBA). Intermediate precision and robustness of the isolation method was investigated, identifying eluent pH as the most important parameter. Investigation of the elution behaviour of the most important fission and activation products and actinides indicated that preventing the accumulation of cesium on the cation exchange column required further isocratic elution with a higher concentrated a-HIBA solu- tion after elution of the lanthanides. A sample matrix free of carbon was achieved by means of acid digestion, fol- lowed by UV photo-oxidation, resulting in samples suit- able for mass spectrometric analysis." "Towards next generation high throughput ion exchange membranes for downstream bioprocessing: A review" "Xing Yang" "Membrane chromatography is recognised as a potential solution to streamline downstream processing for protein purification, where ion exchange membrane chromatography (IEMC) as a polishing step to remove impurities has been successfully demonstrated in small scales. Despite limited commercial adoption in large-scale production, the concept of IEMC attracts many interests and tremendous progress is made. To fill the review gap for advancements in the last decade, this article provides a timely analysis on key performance-determining aspects in IEMC systems. Modern laboratory-made membranes with polymeric chains of tuneable surface area and charge allow for high binding capacity (up to 10-fold higher than that of traditional resins) while simultaneously mitigating the loss of permeance due to the introduction of grafted layers up to 40%. Nevertheless, robust evaluation are yet to be conducted. Despite making equal contribution to binding, the review on process-related work was supported by only" "Evaluation of dry ashing in conjunction with ion chromatographic determination of transition metal ions in pig feed samples" "Marleen R Van paemel, Herman De Rycke, Sam Millet, Myriam Hesta, Geert P J Janssens" "The contents of transition metal ions iron, copper, zinc, and manganese were simultaneously determined in pig feed using an ion chromatographic technique (IC) preceded by dry ashing. Employing ion exchange, the ions were separated on an IonPac CS5A column used in combination with a pyridine-2,6-dicarboxylic acid based eluent. The separation was followed by spectrophotometric detection after postcolumn reaction with 4-(2-pyridylazo)resorcinol. Dry ashing parameters were varied to assess their role in potential analyte loss. Quantitative recoveries (>95%) were obtained for all analytes with a dry ashing method that included a moderate temperature-time regime and ash leaching support in the form of sonication and heat treatment. The use of HCl as leaching acid and the presence of alkaline earths in the matrix solution did not interfere with the chromatographic separation."