TY - THES A1 - Abbas, Ioana M. T1 - Development of LC-MS/MS methods for the quantitative determination of hepcidin-25, a key regulator of iron metabolism N2 - Isotope-dilution liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS) is emerging in the field of clinical chemistry and laboratory medicine as an alternative to immunoassays and is acknowledged as the MS “gold standard” for small biomolecule quantification. Hepcidin-25, a key iron-regulatory peptide hormone discovered in 2000, has revolutionized the understanding of iron disorders and its quantitative determination in biological samples should advance the management of iron-related pathology (diagnosis, prognosis and treatment). This study applied LC-MS/MS, using the triple quadrupole (QqQ) mass spectrometer, in a rapid and robust analytical strategy for the quantification of hepcidin-25 in human serum, to be implemented in routine laboratories. For this purpose, two sample preparation strategies and two complementary chromatographic separation conditions were investigated, where the use of acidic mobile phases (0.1% trifluoroacetic acid) was compared with a novel approach involving solvents at high pH (containing 0.1% ammonia). The application of these LC-MS/MS methods to human samples in an intra-laboratory comparison, using the same hepcidin-25 calibrators, yielded a very good correlation of the results. The LC-MS/MS employing trifluoroacetic acid-based mobile phases was selected as a highly sensitive (limit of quantification LOQ of 0.5 μg/L) and precise (coefficient of variation CV<15%) method and was recommended as a reference method candidate for hepcidin-25 quantification in real samples (in the dynamic range of 0.5-40 μg/L). One of the novel aspects of the methodology was the use of amino- and fluoro-silanized autosampler vials to reduce the interaction of the 25-residue peptide to laboratory glassware surfaces. Moreover, this LC-MS/MS method was used for an international round robin study, applying a secondary reference material as a calibrator. By determining the degree of equivalence between the results of the ten participating methodologies, the performance of the method developed in this study was found to be in the optimal range as defined by the International Consortium for Harmonization of Clinical Laboratory Results (ICHCLR). In this work, the formation of hepcidin-25 complexes with copper(II) was investigated. The first reversed-phase chromatographic separation of hepcidin-25/Cu2+ and hepcidin-25 (copper “free”) was achieved by applying mobile phases containing 0.1% of ammonia (pH 11). LC-MS/MS and high-resolution mass spectrometry (Fourier-transform ion cyclotron resonance (FTICR) MS) were applied for the mass spectrometric characterization of the formed hepcidin-25-Cu(II) species at pH values of 11 and 7.4 respectively. A new species corresponding to hepcidin-25 complexed with two copper ions was identified at high pH. KW - Copper KW - LC-MS/MS KW - Chromatography KW - Mass spectrometry KW - Metal complex KW - Metalloprotein KW - Peptide KW - Metrology KW - Reference material PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:11-110-18452/20119-6 UR - https://edoc.hu-berlin.de/handle/18452/20119?show=full DO - https://doi.org/10.18452/19358 SP - 1 EP - 156 CY - Berlin AN - OPUS4-45780 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Abbas, Ioana M. A1 - Vranic, M. A1 - Hoffmann, Holger A1 - El-Khatib, Ahmed H. A1 - Montes-Bayón, M. A1 - Möller, H. M. A1 - Weller, Michael G. T1 - Investigations of the copper peptide hepcidin-25 by LC-MS/MS and NMR (+) JF - International Journal of Molecular Sciences N2 - Hepcidin-25 was identified as the main iron regulator in the human body, and it by binds to the sole iron-exporter ferroportin. Studies showed that the N-terminus of hepcidin is responsible for this interaction, the same N-terminus that encompasses a small copper(II)-binding site known as the ATCUN (amino-terminal Cu(II)- and Ni(II)-binding) motif. Interestingly, this copper-binding property is largely ignored in most papers dealing with hepcidin-25. In this context, detailed investigations of the complex formed between hepcidin-25 and copper could reveal insight into its biological role. The present work focuses on metal-bound hepcidin-25 that can be considered the biologically active form. The first part is devoted to the reversed-phase chromatographic separation of copper-bound and copper-free hepcidin-25 achieved by applying basic mobile phases containing 0.1% ammonia. Further, mass spectrometry (tandem mass spectrometry (MS/MS), high-resolution mass spectrometry HRMS)) and nuclear magnetic resonance (NMR) spectroscopy were employed to characterize the copper-peptide. Lastly, a three-dimensional (3D)model of hepcidin-25with bound copper(II) is presented. The identification of metal complexes and potential isoforms and isomers, from which the latter usually are left undetected by mass spectrometry, led to the conclusion that complementary analytical methods are needed to characterize a peptide calibrant or reference material comprehensively. Quantitative nuclear magnetic resonance (qNMR), inductively-coupled plasma mass spectrometry (ICP-MS), ion-mobility spectrometry (IMS) and chiral amino acid analysis (AAA) should be considered among others. KW - Metalloprotein KW - Peptide KW - Chromatography KW - High pH KW - Mobile phase KW - Metrology KW - Purity KW - Reference material KW - ATCUN KW - Copper KW - Nickel PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-457796 UR - http://www.mdpi.com/1422-0067/19/8/2271 DO - https://doi.org/10.3390/ijms19082271 SN - 1422-0067 VL - 19 IS - 8 SP - 2271, 1 EP - 16 PB - MDPI CY - Basel AN - OPUS4-45779 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Abbas, Ioana M. A1 - Hoffmann, Holger A1 - Montes-Bayón, M. A1 - Weller, Michael G. T1 - Improved LC-MS/MS method for the quantification of hepcidin-25 in clinical samples JF - Analytical and Bioanalytical Chemistry N2 - Mass spectrometry-based methods play a crucial role in the quantification of the main iron metabolism regulator hepcidin by singling out the bioactive 25-residue peptide from the other naturally occurring N-truncated isoforms (hepcidin-20, -22, -24), which seem to be inactive in iron homeostasis. However, several difficulties arise in the MS analysis of hepcidin due to the sticky character of the peptide and the lack of suitable standards. Here, we propose the use of amino- and fluoro-silanized autosampler vials to reduce hepcidin interaction to laboratory glassware surfaces after testing several types of vials for the preparation of stock solutions and serum samples for isotope dilution liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS). Furthermore, we have investigated two sample preparation strategies and two chromatographic separation conditions with the aim of developing an LC-MS/MS method for the sensitive and reliable quantification of hepcidin-25 in serum samples. A chromatographic separation based on usual acidic mobile phases was compared with a novel approach involving the separation of hepcidin-25 with solvents at high pH containing 0.1% of ammonia. Both methods were applied to clinical samples in an intra-laboratory comparison of two LC-MS/MS methods using the same hepcidin-25 calibrators with good correlation of the results. Finally, we recommend an LC-MS/MS-based quantification method with a dynamic range of 0.5–40 μg/L for the assessment of hepcidin-25 in human serum that uses TFA-based mobile phases and silanized glass vials. KW - HPLC KW - Liquid chromatography KW - Mass spectrometry KW - Silanization KW - Mobile phase KW - Adsorption KW - Peptide losses KW - Recovery KW - Validation KW - Quality control KW - QC KW - Iron disorders KW - Chronic kidney disease KW - Metrology KW - Round robin exercise KW - Basic solvent KW - Peptide analysis PY - 2018 DO - https://doi.org/10.1007/s00216-018-1056-0 SN - 1618-2642 SN - 1618-2650 VL - 410 IS - 16 SP - 3835 EP - 3846 PB - Springer Nature CY - Heidelberg AN - OPUS4-45053 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Unger, Wolfgang T1 - Metrology for spatially resolved chemical analysis at the micro and nanometre scales Surface Analysis Working Group (SAWG) - Report for 16th Meeting (2017/18) N2 - Following the 2017 meeting, progress with the Key Comparison CCQM-K153 related to the BET specific surface lead by UNIIM and the Pilot Study P-190 “Thickness Measurement of nm HfO2 Films” lead by KRISS will be discussed. The 16th meeting of SAWG will focus on •survey on CMC claims submitted with reference to K-129 and K-136. •the overall and SAWG specific aspects of the CCQM Strategy process, •a consideration of comparisons on convention methods as recommended by the CCQM Plenary Meeting 2017, •the 2019 CCQM Workshop and paper(s) for Metrologia’s Special Issue, •discussion of future comparisons. T2 - 24th meeting of the CCQM 2018 CY - Paris, France DA - 19.04.2018 KW - Surface chemical analysis KW - Metrology KW - Inter-laboratory comparisons PY - 2018 AN - OPUS4-44998 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Léonard, Fabien A1 - Bruno, Giovanni T1 - Metrology for additively manufactured medical implants N2 - Additive manufacturing (AM) offers an effective solution to the medical sector. It enables the production, on demand, of customised implants which match the patient’s anatomy, with grafts that promote bone growth, as well as surgical guides that help the surgeons. The objective of this project is to provide a comprehensive basis to enable the safe use of medical AM products with traceable and reliable dimensionalmeasurements. This will guarantee the reliability of medical AM products to notified bodies and facilitate acceptance of AM in the medical sector for a better quality of life. T2 - 8th iCT 2018 conference CY - Wels, Austria DA - 06.02.2018 KW - Implants KW - Metrology KW - Additive manufacturing PY - 2018 AN - OPUS4-44400 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Anja A1 - Lippitz, Andreas A1 - Swaraj, Sufal A1 - Sparnacci, Katia A1 - Unger, Wolfgang T1 - Progress Talk 3 / Investigating the dimensions of core|shell nanoparticles using scanning transmission X-ray microscopy (STXM) N2 - This presentation deals with the progress between month twelve and nineteen of my PhD thesis. I prepared it, in order to update my supervisor Prof. Kemnitz and my colleagues from the department of chemistry at the Humboldt-Universität zu Berlin (HU). T2 - Working Group Meeting of Prof. Erhard Kemnitz CY - Humboldt-Universität zu Berlin (HU), Germany DA - 30.01.2018 KW - Core-shell nanoparticles KW - Metrology KW - PS KW - PTFE KW - Polymers KW - SEM KW - STXM PY - 2018 N1 - Geburtsname von Müller, Anja: Hermanns, A. - Birth name of Müller, Anja: Hermanns, A. AN - OPUS4-43981 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -