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Current Project

Analytical Chemistry Division (V)

 

Number: 2005-035-2-500

Title: Trace elements analysis: role of grain size distribution in solid reference materials

Task Group
Chairman:
Maria Belli

Members: Ales Fajgelj, Zoltan Mester, Umberto Sansone, and Gemma Rauret

Objective:
Generally, solid reference materials (RM) of the same matrix from different producers can present different particles size distributions and this could affect the homogeneity of the material and the minimum representative sample required for trace elements analysis. The final aim of the proposed project is to develop a guide to be used by reference materials producers and by the analytical community to select the most appropriate particle size distribution of a considered reference material to fit the analytical needs.

Description:
The existing guidelines for Reference Material (RM) producers do not report any indication for the selection of the most appropriate particle size distribution during the production of these materials. In the case of solid RM, particle size distribution plays a vital role on the homogeneity of the material and on the minimum representative sample required for trace element analysis. Generally, RMs of the same matrix but from different producers show different particle size distributions.For soil and sediment RMs, particle size distribution can vary from <120 µm to <20µm. From one side, finer particles can increase the homogeneity of the material (between and within bottle homogeneity) but from the other side, the RM obtained can be different, in terms of grain size, by the real samples routinely analyzed in the laboratories (e.g. contaminated soil analysis commonly is carried out on samples particle size < 2 mm). In addition, the effect of particle size on extractable trace metals in soil RM has been already observed [A. Sahuquillo et al., Certified reference materials for extractable trace metals in soils: effect of the particle size, 1998, Fresenius J. Anal. Chem. 304-307]. It is also relevant to point out that the production of RMs with finer particles has a negative effect on the cost of RMs production. The proposed project will focus on soil/sediment candidate RMs with different trace element contents.

The project will bring together the results of experimental work that is being funded by different participants. The main aim is to investigate:

  • the influence of grain size distribution on the within and between bottles homogeneity;
  • the influence of grain size distribution on the minimum sample required for trace elements analysis;
  • the influence of grain size distribution on the stability of trace elements;
  • the cost associated with the production of RMs with different particles size distribution.

The results of the proposed project will be made available in a guide that can be useful for RM producers to select fit for purpose methods for RMs preparation and for the analytical community to select fit for purpose RMs.

Progress:

 

Last Update: 6 June 2006

<project announcement published in Chem. Int Nov/Dec 2006>

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