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Erratum to: Monitoring antigenic protein integrity during glycoconjugate vaccine synthesis using capillary electrophoresis-mass spectrometry (Analytical and Bioanalytical Chemistry, (2016), 408, 22, (6123-6132), 10.1007/s00216-016-9723-5)
No full textUnfortunately the name of Luciano Piubelli was missing as co-author of this contribution. The correct list of authors is: Sara Tengattini, Elena Domínguez-Vega, Luciano Piubelli, Caterina Temporini, Marco Terreni, Govert W. Somse
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Hydrophilic interaction chromatography–mass spectrometry for anionic metabolic profiling of urine from antibiotic-treated rats
No full textHydrophilic interaction chromatography–mass spectrometry (HILIC–MS) was used for anionic metabolic profiling of urine from antibiotic-treated rats to study microbial–host co-metabolism. Rats were treated with the antibiotics penicillin G and streptomycin sulfate for four or eight days and compared to a control group. Urine samples were collected at day zero, four and eight, and analyzed by HILIC–MS. Multivariate data analysis was applied to the urinary metabolic profiles to identify biochemical variation between the treatment groups. Principal component analysis found a clear distinction between those animals receiving antibiotics and the control animals, with twenty-nine discriminatory compounds of which twenty were down-regulated and nine up-regulated upon treatment. In the treatment group receiving antibiotics for four days, a recovery effect was observed for seven compounds after cessation of antibiotic administration. Thirteen discriminatory compounds could be putatively identified based on their accurate mass, including aconitic acid, benzenediol sulfate, ferulic acid sulfate, hippuric acid, indoxyl sulfate, penicillin G, phenol and vanillin 4-sulfate. The rat urine samples had previously been analyzed by capillary electrophoresis (CE) with MS detection and proton nuclear magnetic resonance (1H NMR) spectroscopy. Using CE–MS and 1H NMR spectroscopy seventeen and twenty-five discriminatory compounds were found, respectively. Both hippuric acid and indoxyl sulfate were detected across all three platforms. Additionally, eight compounds were observed with both HILIC–MS and CE–MS. Overall, HILIC–MS appears to be highly complementary to CE–MS and 1H NMR spectroscopy, identifying additional compounds that discriminate the urine samples from antibiotic-treated and control rats
Extending the span of angular-scanning surface plasmon resonance biosensing: hyphenation, variable-wavelength excitation, and multiplexing
Get PDFAdvanced bioactivity screening analytics for rapid identification of environmental toxicants
Get PDFSomsen, G.W. [Promotor]Kool, J. [Copromotor
Capillary electrophoresis-mass spectrometry for the identification of aminopyrene trisulfonic acid labeled glycans
Get PDFThe aim of this work was the development of capillary-electrophoresis/mass spectrometry (CE-MS) methods with high separation power for the characterization of aminopyrene-trisulfonic acid (APTS)-labeled glycans. State of the art for routine glycan analysis is capillary sieving electrophoresis with laser induced fluorescence detection (CSE-LIF) using the fluorescent APTS. However, a firsthand identification of glycans is not possible. This thesis presents two high performance CE-MS methods, with appropriate separation efficiency (i.e. resolution of structural isomers) for biopharmaceutical samples. The first method uses a novel alkaline background electrolyte (BGE) for the simultaneous analysis of APTS-labeled as well as charged native glycans. The alkaline BGE enables a robust CE-MS application and the determination of derivatization and ionization efficiency. The glycans of several different types of biopharmaceutically relevant proteins could be identified. The second CE-MS method, acidic BGE, was optimized in terms of separation efficiency and reproducibility by investigating potential system affecting parameters. Sheath liquid (SL) composition and pressure effects have the strongest impact on the desired high separation efficiency. Despite its sensitivity to pressure, the resulting method shows good reproducibility, since the main treats are clearly determined and pressure impacts can be counterbalanced. A systematic study on the signal assignment of glycans, analyzed by two different CSE-LIF methods and the proposed CE-MS methods, shows that the linear mobility correlation of glycans with similar functional groups within the two systems allows the signal assignment and identification of CE-LIF signals based on several known reference glycans. The development of a fritless, in-line solid phase extraction (SPE) setup, using a novel bead-string SPE design decreased the limit of detection of the acidic CE-MS method, from the sub-µM-range to a low nM-range
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Anionic metabolic profiling of urine from antibiotic-treated rats by capillary electrophoresis–mass spectrometry
No full textA recently developed capillary electrophoresis (CE)-negative-ionisation mass spectrometry (MS) method was used to profile anionic metabolites in a microbial-host co-metabolism study. Urine samples from rats receiving antibiotics (penicillin G and streptomycin sulfate) for 0, 4, or 8 days were analysed. A quality control sample was measured repeatedly to monitor the performance of the applied CE-MS method. After peak alignment, relative standard deviations (RSDs) for migration time of five representative compounds were below 0.4 %, whereas RSDs for peak area were 7.9–13.5 %. Using univariate and principal component analysis of obtained urinary metabolic profiles, groups of rats receiving different antibiotic treatment could be distinguished based on 17 discriminatory compounds, of which 15 were downregulated and 2 were upregulated upon treatment. Eleven compounds remained down- or upregulated after discontinuation of the antibiotics administration, whereas a recovery effect was observed for others. Based on accurate mass, nine compounds were putatively identified; these included the microbial-mammalian co-metabolites hippuric acid and indoxyl sulfate. Some discriminatory compounds were also observed by other analytical techniques, but CE-MS uniquely revealed ten metabolites modulated by antibiotic exposure, including aconitic acid and an oxocholic acid. This clearly demonstrates the added value of CE-MS for nontargeted profiling of small anionic metabolites in biological samples
Photodegradation Illuminated: New analytical tools for studying photochemical processes
Get PDFThe study of photodegradation processes concerns many fields, including those of cultural heritage, the food industry, and water purification. In each of these areas, different questions concerning photodegradation arise, but generally, they are related to either (i) the prevention of photodegradation aiming to avoid loss or change of properties, such as color, taste or smell, or (ii) the exploitation of photodegradation for removal of potentially harmful compounds in, e.g., drinking water. Studying light-induced degradation (LID) reactions is challenging and often it is difficult to establish a strong link between the degradation and the starting products. Several techniques and approaches for studying photodegradation had been developed previously, but these can be laborious and prone to errors. A solution to this could be found in a comprehensive, automated device that enables simultaneous sample irradiation of compounds in solution and chemical analysis in real-time and after photodegradation. The need for such an analytical platform is clarified in Chapter 1. The ‘Toolbox for studying the Chemistry Of Light-induced Degradation’ (TooCOLD) project envisioned to develop an integrated device. It would encompass a light-exposure cell, allow in-situ spectroscopic monitoring of the irradiated sample and on-line coupling to liquid chromatography (LC) with diode array detection (DAD) and mass spectrometry (MS) for direct identification of degradation products formed during irradiation. This thesis describes the step-wise development of such an automated device employing a gas-permeable liquid-core waveguide (LCW) as a light-exposure cell, a sample handler, a spectrograph for in-situ absorption spectroscopy, and switching valves for coupling to LC-DAD-QTOFMS. The full device was applied to study the photodegradation of several compounds to evaluate and demonstrate its analytical performance. Ideally, parameters that affect photodegradation should be known to aid the design of a system that can be used to study photodegradation in the broadest sense. Chapter 2 describes the many parameters that can influence the photodegradation of dyes and pigments in solution and on a substrate. The light-exposure cell developed in this project was based on an LCW, which employs the principle of total internal reflection (TIR) to irradiate the sample from within in contrast to using perpendicular illumination. Chapter 3 reviews the different types of LCWs that are available and applicable as a photoreactor and for chemical analysis. The analysis of complex mixtures resulting from photodegradation may be challenging as the chemical properties of the components can vary greatly. Chapter 4 describes the development of a generic LC-DAD method for the analysis of natural and synthetic dyes. Chapter 5 describes the development and overall performance of a low-volume LID cell based on a gas-permeable LCW made of Teflon AF2400 connected to a spectrograph, allowing the collection of spectral data in real-time. All of the abovementioned results were included in the design of a full prototype of an LID-cell based device. Chapter 6 describes the analytical performance of the fully automated system coupled to LC-DAD. Chapter 7 describes the study to the effect of oxygen on the photodegradation of Riboflavin and EY using the final prototype of the device coupled to LC-DAD-QTOFMS. The feasibility of Raman spectroscopy for studying changes in the molecular structure during irradiation was assessed in several exploratory subprojects, discussed in Chapter 8. Surface-enhanced Raman spectroscopy (SERS) using silver colloids was compared to on-chip SERS monitoring during the photodegradation of CV using leaning pillar chip substrates. Finally, carbon paper was used as a gas-permeable SERS substrate for the implementation inside a microfluidic device. Finally, Chapter 9 contains conclusions on the work covered in Chapters 1 to 8, discussing several relevant aspects and providing perspectives on future use of the developed system, optimization strategies, and possible new application areas
Metabolomics: From Method Development to System Biology
Get PDFTeusink, B. [Promotor]Somsen, G.W. [Promotor]Giera, M.A. [Copromotor
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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