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| Titel |
An inter-laboratory investigation of the Arctic sea ice biomarker proxy IP25 in marine sediments: key outcomes and recommendations |
| VerfasserIn |
S. T. Belt, T. A. Brown, L. Ampel, P. Cabedo-Sanz, K. Fahl, J. J. Kocis, G. Massé, A. Navarro-Rodriguez, J. Ruan, Y. Xu |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 10, no. 1 ; Nr. 10, no. 1 (2014-01-21), S.155-166 |
| Datensatznummer |
250116901
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| Publikation (Nr.) |
 copernicus.org/cp-10-155-2014.pdf |
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| Zusammenfassung |
| We describe the results of an inter-laboratory investigation into the
identification and quantification of the Arctic sea ice biomarker proxy
IP25 in marine sediments. Seven laboratories took part in the study, which
consisted of the analysis of IP25 in a series of sediment samples from
different regions of the Arctic, sub-Arctic and Antarctic, additional
sediment extracts and purified standards. The results obtained allowed 4 key
outcomes to be determined. First, IP25 was identified by all
laboratories in sediments from the Canadian Arctic with inter-laboratory
variation in IP25 concentration being substantially larger than within
individual laboratories. This greater variation between laboratories was
attributed to the difficulty in accurately determining instrumental response
factors for IP25, even though laboratories were supplied with
appropriate standards. Second, the identification of IP25 by 3
laboratories in sediment from SW Iceland that was believed to represent a
blank, was interpreted as representing a better limit of detection or
quantification for such laboratories, contamination or mis-identification.
These alternatives could not be distinguished conclusively with the data
available, although it is noted that the precision of these data was
significantly poorer compared with the other IP25 concentration
measurements. Third, 3 laboratories reported the occurrence of IP25 in
a sediment sample from the Antarctic Peninsula even though this biomarker is
believed to be absent from the Southern Ocean. This anomaly is attributed to
a combined chromatographic and mass spectrometric interference that results
from the presence of a di-unsaturated highly branched isoprenoid (HBI)
pseudo-homologue of IP25 that occurs in Antarctic sediments. Finally,
data are presented that suggest that extraction of IP25 is consistent
between Accelerated Solvent Extraction (ASE) and sonication methods and that
IP25 concentrations based on 7-hexylnonadecane as an internal standard
are comparable using these methods. Recoveries of some more unsaturated HBIs
and the internal standard 9-octylheptadecene, however, were lower with the
ASE procedure, possibly due to partial degradation of these more reactive
chemicals as a result of higher temperatures employed with this method. For
future measurements, we recommend the use of reference sediment material
with known concentration(s) of IP25 for determining and routinely
monitoring instrumental response factors. Given the significance placed on
the presence (or otherwise) of IP25 in marine sediments, some further
recommendations pertaining to quality control are made that should also
enable the two main anomalies identified here to be addressed. |
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