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W. Nischkauer, M.-A. Néouze, A. Limbeck:
"Enrichment Of Palladium From Aqueous Sample Solutions Using Functionalized Nano- Particles";
Vortrag: Euroanalysis 16, Belgrad; 11.09.2011 - 15.09.2011; in: "Compendium of all Abstracts", (2011), S. 129.

Pd is widely used in today´s automotive catalytic converters. Thermal and mechanical stress cause surface abrasion of the catalytic material, releasing Pd in the environment [1]. Due to its potentially harmful properties, it has become necessary to perform analysis of very low concentrations of Pd in environmental samples. The methods at hand for this task are ICP-MS, ICP-AES or ET-AAS [1]. Unfortunately, when using these methods, Pd is either strongly interfered by other elements (ICP-MS) or sensitivity does not allow measurements in the desired concentration range (ICP-AES, ET-AAS). To improve detection limits and to eliminate interferences usually sample pre-treatment techniques like solid phase extraction (SPE) with ion-exchangers are applied. Although being well established, SPE suffers from several shortcomings such as time consuming conditioning steps, incomplete recovery of the adsorbed ions and memory effects. One of the major drawbacks of SPE is the necessity to elute the analyte after adsorption using appropriate solvents.

In this work a novel sample pre-treatment procedure for enriching Pd from liquid samples is presented, featuring the idea of renewable surfaces and eliminating any elution process. Porous nano- spherical silica was functionalized with quarternary ammonium groups [2], yielding a strong anion exchanging material with a mean particle size of 700nm. Due to the high specific surface of the silica, very low amounts of this compound are sufficient to obtain nearly quantitative recovery for Pd from aqueous solutions. After separating the particles from the sample volume by means of a centrifuge and removing excess liquid, an aliquot of the remaining suspension is analyzed using ET-AAS. This straight- forward slurry approach helps to overcome the problems associated with the elution process. On that account it is possible to enrich Pd from aqueous solutions or sample digests, propelling the limit of detection in the 100ng/L range.

Functionalized Nanoparticles, Enrichment procedures, ETAAS