Publication Date:
2016-09-15
Description:
Conventional simultaneous CNS stable isotope abundance measurements of solid samples usually require high sample amounts, up to 1 mg carbon, to achieve exact analytical results. This rarely used application is often impaired by high C:S element ratios when organic samples are analyzed and problems such as incomplete conversion into sulphur dioxide occur during analysis. We introduce, as a technical innovation, a high sensitivity elemental analyzer coupled to a conventional isotope ratio mass spectrometer, with which CNS-stable isotope ratios can be determined simultaneously in samples with low carbon content (〈40 mu g C corresponding to similar to 100 mu g dry weight). The system includes downsized reactors, a temperature program-controlled gas chromatography (GC) column and a cryogenic trap to collect small amounts of sulphur dioxide. This modified application allows for highly sensitive measurements in a fully automated operation with standard deviations better than +/-0.47 parts per thousand for delta N-15 and delta S-34 and +/-0.12 parts per thousand for delta C-13 (n=127). Samples collected from one sampling site in a Baltic fjord within a short time period were measured with the new system to get a first impression of triple stable isotope signatures. The results confirm the potential of using delta S-34 as a stable isotope tracer in combination with delta N-15 and delta C-13 measurements to improve discrimination of food sources in aquatic food webs. Copyright (C) 2009 John Wiley & Sons, Ltd
Type:
Article
,
PeerReviewed
Format:
text
