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W. Nischkauer, K. Schröder, F. Vanhaecke, A. Limbeck:
"Dispersed Particle Extraction For The Straight-Forward Quantification Of Iron In Sea Water";
Poster: Euroanalysis XVIII, Bordeaux, France; 09-06-2015 - 09-10-2015; in: "Book of Abstracts", (2015), 1 pages.

In many regions of the oceans, nutrients are available abundantly. However, iron is a limiting factor for phytoplankton growth, as it has only a low solubility in sea-water. Quantifying iron in sea-water is therefore essential for understanding bio-mass cycles in the oceans.
As mentioned above, iron-concentrations in sea-water are low (around 0.5 µg L-1). It is difficult to reliably quantify such low iron-concentrations in a saline matrix: inductively-coupled plasma (ICP) optical emission spectrometry (OES) is hampered by its sensitivity, whereas ICP mass spectrometry (MS) suffers from the high salt-load.
To overcome this challenge, two analytical strategies can be applied: analyte pre-concentration or matrix separation. Conventionally, both are achieved via solid-phase extraction (SPE), but, in spite of being well-established, SPE suffers from low sample throughput.
To overcome this, dispersed particle extraction was applied in this contribution. Here, a sorbent material is suspended directly in the liquid sample. After retention of the analytes on the sorbent surface, the micrometer-sized particles are separated from the surrounding solution by centrifuging and decanting the supernatant. Then, the analyte is re-mobilized from the sorbent surface by a pH-shift. The obtained clear solution is then analyzed. Thus, no packed beds like in column-SPE are required. This brings the advantage of fast sample throughput.
In the here presented analytical set-up, quantification of iron in seawater was achieved with dispersed particle extraction using cellulose coated with a task-specific ionic liquid. The method was validated by spike-recovery experiments, as well as by analysis of NASS-6 certified reference material.

ICP-OES, dispersed particle extraction, sea water, ionic liquids