Dr.-Ing. Julian Renpenning
|since 2015||Postdoc at UFZ, Department of Isotope Biogeochemistry|
|2011-2015||PhD student at UFZ, Department of Isotope Biogeochemistry|
|2011||Department of Molecular Microbiology and Biotechnology, University of Leiden, The Netherlands|
|2009-2010||Diploma degree in Bioprocess Engineering and Analytics at the Department of Bioprocess Technology|
|2004-2010||Biotechnology study at Technical University of Berlin|
Analytical method development for stable isotope measurements of hydrogen, chlorine, bromine, sulfur and others. In order to achieve our goals several techniques for online stable isotope analysis are applies, as i.e. elemental analyzer (EA), gas chromatography (GC) or liquid chromatography (LC) coupled to conversion units and mass detectors, as ion trap mass spectrometer (itMS), isotope-rato mass spectrometer (IRMS), multi-collector ion coupled plasma mass spectrometer (MC-ICPMS), as high-resolution mass spectrometer (Orbitrap MS).
Hydrogen isotope analysis
The conventional high-temperature conversion (HTC) approach towards hydrogen compound-specific isotope analysis (CSIA) of halogen-bearing (F, Cl, Br, I) organics suffers from incomplete H2 yields and associated hydrogen isotope fractionation due to generation of HF, HCl, HBr, and HI byproducts. This project is working on chromium-based high-temperature conversion (Cr/HTC) approach for hydrogen isotope analysis of various fluorinated, chlorinated, brominated and iodinated organic compounds. The Cr/HTC approach is fast, economical, and not affected by low H2 yields and associated isotope fractionation. The optimized Cr/HTC reactor setup for EA and GC interfaces can be implemented in existing analytical equipment using commercially available reactor materials. The sensitivity and simplicity of the chromium-based HTC approach provides a promising routine tool for hydrogen isotope analysis for a wide range of hetero-element bearing compounds.
Chlorine isotope analysis
Chlorine isotope analysis of organic compounds has considerably developed within the last decade due to increased interest in multi-dimensional isotope analysis. Existing methods, however, still suffer from large sample needs (thermal ionisation mass spectrometry), mediocre precision (gas chromatography quadrupol mass spectrometry) or limitation to a few compounds only (gas source isotope ratio mass spectrometry). We are working on a method for chlorine isotope analysis of aliphatic and aromatic hydrocarbons that overcomes the limitations of previous techniques combining universality, low detection limits and excellent precision using a GC-ICPMS. This universal method considerably simplifies δ37Cl determination of mixtures of halogenated organic compounds and may be easily adapted to other GC-ICPMS systems.
List of publications
 J. Renpenning, A. Schimmelmann, M. Gehre. Compound-specific hydrogen isotope analysis of fluorine-, chlorine-, bromine- and iodine-bearing organics using gas chromatography-chromium-based high-temperature conversion (Cr/HTC)-isotope ratio mass spectrometry. Rapid Commun Mass Spectrom 2017, n/a.
 M. Gehre, J. Renpenning, H. Geilmann, H. Qi, T. B. Coplen, S. Kummel, N. Ivdra, W. A. Brand, A. Schimmelmann. Optimization of on-line hydrogen stable isotope ratio measurements of halogen- and sulfur-bearing organic compounds using elemental analyzer-chromium/high-temperature conversion isotope ratio mass spectrometry (EA-Cr/HTC-IRMS). Rapid Commun. Mass Spectrom. 2017, 31, 475.
 J. Renpenning, I. Nijenhuis, in Organohalide-Respiring Bacteria (Eds.: L. Adrian, E. F. Löffler), Springer Berlin Heidelberg, Berlin, Heidelberg, 2016, pp. 429.
 I. Nijenhuis, J. Renpenning, S. Kümmel, H. H. Richnow, M. Gehre. Recent advances in multi-element compound-specific stable isotope analysis of organohalides: Achievements, challenges and prospects for assessing environmental sources and transformation. Trends Environ. Anal. Chem. 2016, 11, 1.
 M. Gehre, J. Renpenning, H. Geilmann, H. Qi, T. B. Coplen, S. Kümmel, N. Ivdra, W. A. Brand, A. Schimmelmann. Tables supporting optimization of on-line hydrogen stable isotope-ratio measurements of halogen- and sulfur-bearing organic compounds using elemental analyzer-chromium/high-temperature conversion-isotope-ratio mass spectrometry. U.S. Geological Survey data release 2016.
 J. Renpenning, I. Rapp, I. Nijenhuis. Substrate hydrophobicity and cell composition influence the extent of rate limitation and masking of isotope fractionation during microbial reductive dehalogenation of chlorinated ethenes. Environ Sci Technol 2015, 49, 4293.
 J. Renpenning, S. Kümmel, K. L. Hitzfeld, A. Schimmelmann, M. Gehre. Compound-specific hydrogen isotope analysis of heteroatom-bearing compounds via gas chromatography-chromium-based high-temperature conversion (Cr/HTC)-isotope ratio mass spectrometry. Anal. Chem. 2015, 87, 9443.
 J. Renpenning, K. L. Hitzfeld, T. Gilevska, I. Nijenhuis, M. Gehre, H. H. Richnow. Development and validation of an universal interface for compound-specific stable isotope analysis of chlorine (37Cl/35Cl) by GC-high-temperature conversion (HTC)-MS/IRMS. Anal. Chem. 2015, 87, 2832.
 M. Gehre, J. Renpenning, T. Gilevska, H. Qi, T. B. Coplen, H. A. Meijer, W. A. Brand, A. Schimmelmann. On-line hydrogen-isotope measurements of organic samples using elemental chromium: an extension for high temperature elemental-analyzer techniques. Anal. Chem. 2015, 87, 5198.
 J. Renpenning, S. Keller, S. Cretnik, O. Shouakar-Stash, M. Elsner, T. Schubert, I. Nijenhuis. Combined C and Cl isotope effects indicate differences between corrinoids and enzyme (Sulfurospirillum multivorans PceA) in reductive dehalogenation of tetrachloroethene, but not trichloroethene. Environ Sci Technol 2014, 48, 11837.
 U. Schimpf, A. Hanreich, P. Mähnert, T. Unmack, S. Junne, J. Renpenning, R. Lopez-Ulibarri. Improving the Efficiency of Large-Scale Biogas Processes: Pectinolytic Enzymes Accelerate the Lignocellulose Degradation. Journal of Sustainable Energy & Environment 2013, 4, 53.