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Free keywords:
carbon-13
isotope measurement methods and equipment
IAEA
measurement
strategy
nitrogen-15
reference materials
reliability of data
Abstract:
Stable isotope ratios are reliable and long lasting process tracers. In order to compare data from different locations or different sampling times at a high level of precision, a measurement strategy must include reliable traceability to an international stable isotope scale via a reference material (RM). Since these international RMs are available in low quantities only, we have developed our own analysis schemes involving laboratory working RM. In addition, quality assurance RMs are used to control the long-term performance of the delta-value assignments. The analysis schemes allow the construction of quality assurance performance charts over years of operation. In this contribution, the performance of three typical techniques established in IsoLab at the MPI-BGC in Jena is discussed. The techniques are (1) isotope ratio mass spectrometry with an elemental analyser for delta N-15 and delta C-13 analysis of bulk (organic) material, (2) high precision delta C-13 and delta O-18 analysis of CO2 in clean-air samples, and (3) stable isotope analysis of water samples using a high-temperature reaction with carbon. In addition, reference strategies on a laser ablation system for high spatial resolution delta C-13 analysis in tree rings is exemplified briefly.
