Bachelor defense: Nicolai Riisbjerg Jørgensen

Title: Isotope-Ratio Mass Spectrometry: Optimization and Measurements

Abstract: Isotope-Ratio Mass Spectrometry (IRMS) is used to perform several measurements of standard gases and unknown air samples at the Centre for Ice and Climate, University of Copenhagen. Dual Inlet IRMS (DI-IRMS) is used to establish a working standard for referencing delta-13C measurements to the VPDB-scale. Parts of an experimental setup (continuous flow IRMS), for purifying and combusting CH4 in air samples, are automated in order to make measurements of delta-13C-CH4 as identical as possible. delta-13C-CH4  measurements of NEEM air standard are used to test the performance of the experimental setup and for uncertainty estimation. Furthermore, delta-13C-CH4 -measurements are used to establish and validate a calibration method for correcting a minor sample size dependent offset in measured delta-13C-CH4 -values. Raw and calibrated measurements of unknown air samples, originating from glacial outflows in Greenland, are presented and a preliminary analysis is given.