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F. Horak, A. Limbeck:
"µ-Dried-Droplets as standards for Tandem single particle LIBS/LA-ICP-MS analysis";
Talk: 2017 Euopean Winter Conference on Plasma Spectrochemistry, Sankt Anton, Arlberg; 02-19-2017 - 02-24-2017; in: "Book of Abstracts", (2017), 102.

The IAEA (International Atomic Energy Agency) can perform environmental sampling at the inspected nuclear facilities to assist in drawing conclusions about the absence of undeclared nuclear material or nuclear activities at the specified location. The size of the collected particles in the environmental swipe samples ranges from nm to several µm, containing Uranium in the pg-range. As these particles are collected together with large quantities of dust matrix, the analysis can be challenging. The low availability of suitable reference materials complicates the instrument tuning for the analysis and characterisation of single particles even further. Thus, optimised methods are required for satisfactory and comprehensive analysis of such particle samples.
In this work, a new approach using Tandem LIBS/LA-ICP-MS was used to analyse the geological matrix simultaneously with the Uranium isotopic composition. The knowledge about the composition of the sample matrix gained from the collected LIBS data, can improve the characterisation of the sample while not influencing trace element analysis using ICP-MS, which applies especially when employing only a single mass analyser. The broadband detection capabilities of a LIBS system alongside with the usually very high sensitivity for many crustal elements can help to identify and correct matrix induced effects in ICP-MS measurements.
A proof of principle study has been performed using µ-Dried-Droplet standards. This approach offers a flexible way to create in-house solutions for applications where appropriate reference materials are not available or cannot satisfy the analytical needs. The elemental and isotopic composition of the µ-droplet is governed by the applied liquid standard. This method allows to easily adapt the total amount of analyte and matrix composition in account to the needs of the current application thanks to the vast variety of available liquid certified reference materials.
In the presented study a variety of Uranium containing mock-up prepared by the above described µ-Dried-Droplets approach was investigated. Thereby prepared mock-up particles had a defined composition regarding their uranium content as well as matrix elements. Even with a quadrupole instrument a satisfactory determination of the uranium isotopic ratio and content as well as the matrix composition could be achieved, demonstrating the usability of this approach for single particle analysis.

Single particle analysis, LA-ICP-MS, LIBS, micro dried droplets