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S. Hossein-Zadegan, W. Nischkauer, M.-A. Néouze, A. Limbeck:
"Rare earth elements determination in urban dust samples by ICP-OES; enrichment by functionalized magnetic nanoparticles";
Vortrag: 10. ASAC Junganalytikerinnenforum, Tulln; 13.06.2014 - 14.06.2014; in: "Book of Abstracts", (2014), S. 32.

The distribution and abundance of REEs vary along with geological conditions, which provides possibility of geochemical fingerprints for extraction missions moreover, investigation of toxicity in human body due to their accumulation in environment following anthropogenic inputs because of low mobility of these elements. However, it is necessary to enrich naturally low concentrated REEs in efficient manner to gain high sensitivity of spectrometry´s methods such as ICP-OES or ICP-MS. Ordinary procedure for analyte enrichment is on the basis of solid phase extraction (SPE). Yet, there are acclaimed disadvantages by using SPE columns including necessity of REE elution with strong solvents, which lead to unsuitable concentrations of injected solutions to the instrument, and deteriorate the efficiency of packed sorbent bed causing low recovery of analytes and high variability in results, respectively.
Recently, we introduced a novel method to overcome the mentioned problems; dispersed particle extraction. This method is based on the use of silica nanoparticles functionalized with strong cation exchange ligands. To avoid the elution step required in conventional SPE, we applied the concept of slurry analysis for measurement of analytes including the sorbent particles. For ICP-OES measurement the slurry is directly introduced into the plasma where first the particles are disintegrated and second the target analytes are atomized and excited.
Here we present a further improvement of the dispersed particle approach, the developed procedure is used to recognise REEs quantitatively in digested urban dust. Magnetic silica coated nanoparticles were produced by addition of silica shell to iron oxide core particles which act as potent sorbent for cations with the sulfonyl groups (strong cationic exchanger) on their surface. Amorphous silica layer is very effective for stabilizing the iron oxide against oxidation, tailoring a uniform particle size and controlling the homogeneous dispersion of the ultra-fine particles. The improvements include smaller particle size providing higher surface area of adsorption, magnetic properties of nanoparticles enabling the use of magnet instead of time consuming centrifugation for particle separation and more stable homogenous solution introducing ICP, respectively. For effective separation and simultaneous enrichment of REE from road dust digests the nanoparticles with the size of 5 nm are suspended into the pH-adjusted samples containing analyte and ammonium buffer, being agitated in ultra-sonic bath, then separated by magnetic field and introduced into the ICP-OES after getting dissolved in microliters of 10% HCl/HF mixture.
Trueness of the method was shown by standard addition and analysis of Certified Refrence Material; NIST2709. Moreover some dust samples from Tabriz (I.R.Iran) and Vienna (Austria) were analysed by this method.

Dispersed particle extraction, magnetic nanoparticles, rare earth elements, dust