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W. Nischkauer, F. Berzsenyi, K. Schröder, F. Vanhaecke, A. Limbeck:
"Selective extraction of iron in the presence of zinc and copper using customized ionic liquids: feasibility and application to digested whole blood";
Poster: 2015 Euopean Winter Conference on Plasma Spectrochemistry, Münster, Germany; 02-22-2015 - 02-26-2015; in: "Book of Abstracts", (2015), 1 pages.

The isotopic composition of iron in human blood has been shown to be an indicator for the iron-status of an individual. This phenomenon could be used for early diagnosis of aberrant iron metabolism, observed in patients suffering from diseases such as hemochromatosis type I or anemia of chronic disease.
Iron-status-induced deviations from the natural iron-isotope ratio, however, are very small. For adequate correction of instrumental mass discrimination in isotopic analysis using multi-collector ICP-MS and for avoiding or mitigating the impact of spectral interferences, it is necessary to isolate the iron fraction out of the whole blood- or serum-matrix. This can be achieved by using column-based chromatographic methods. The selectivity of such methods is based on differences in terms of distribution coefficients between the various matrix and analyte elements and the resin. These differences allow a sequential elution of the elements from the column. Although it is fit for purpose, this approach is laborious and time-consuming. One possibility to enhance the sample throughput is by applying task-specific functional groups that provide a satisfying selectivity towards iron, permitting the use of only one separation step.
In the preliminary study presented here, we have evaluated the performance of six task-specific ionic liquids (TS-ILs) with respect to their selectivity towards iron in the presence of copper and zinc, as well as other matrix constituents commonly observed in blood samples (e.g., Na, K, Sr, Ca, Mg). Under optimized conditions (pH, analyte-TS-ILs-ratio, amount of TS-ILs, reaction time, amount of buffer), recoveries > 90% were achieved with only one extraction step using conventional liquid-liquid extraction (water/n-octanole) and synthetic sample solutions. Changing from synthetic samples to digested human whole blood samples required further optimization in terms of pH-adjustment and complete removal of organic matrix constituents.

Trace metal analysis, whole blood, ionic liquids