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M. Bonta, A. Limbeck:
"Analysis of minor and trace elements in polymers using Tandem LA/LIBS";
Talk: 2017 Euopean Winter Conference on Plasma Spectrochemistry, Sankt Anton, Arlberg; 02-19-2017 - 02-24-2017; in: "Book of Abstracts", (2017), 127.

Nowadays, polymers are used in a wide range of scientific as well as industrial applications. Besides structural and molecular properties, also the concentrations of minor and trace metals in polymers are an important aspect. Increased metal concentrations can influence physical and chemical properties of the products, and especially heavy metals can pose problems for health and environment. Thus, accurate analysis of metals in polymer matrices is required.
Besides X-ray based techniques, where limits of detection are often insufficient, LA-ICP-MS is considered excellently suitable for high-sensitivity determination of a wide elemental range. However, matrix-matched standards are required to tackle the presence of matrix effects when analyzing different polymer types to achieve accurate quantification. Such matrix-matched standards are either commercially unavailable and need to be prepared in-house - which poses major workload -, or the analyzed polymer type is even unknown (e.g., in recycling applications).
In this work, Tandem LA/LIBS instrumentation offering simultaneous sample analysis using LA-ICP-MS and LIBS was applied to tackle this problem. Minor and easily excitable elements (e.g., Li, Na) were analyzed using LIBS, while trace elements could be monitored in the same run of analysis using LA-ICP-MS. Additionally, a wide-wavelength LIBS spectrum also provided information about the matrix composition of the sample by elemental and molecular emissions of the bulk components, further used for statistical data analysis to support multivariate calibration. Polymer layers with known element concentrations were prepared using spin coating, a technique which proved to be a fast and simple approach for the production of polymer standards. With thicknesses in the single digit µm-scale, the layers could even be used to quantify signal intensities obtained from bulk samples. Apart from successful element quantification, different polymers could be distinguished using their characteristic LIBS spectra, containing elemental, as well as molecular emission bands from the bulk polymer components. Trace metals in the polymers which were not accessible for stand-alone LIBS analysis were detected using ICP-MS. Using such combination of LIBS and LA-ICP-MS accurate quantification of trace elements in different bulk samples with known as well as unknown composition could be achieved.

LIBS, LA-ICP-MS, polymer analysis, multivariate calibration