Regresar

Laser-induced breakdown spectroscopy analysis of dried liquids on solid surfaces

Abstract:

In this work, we present a comparison of analytical substrates made by scratching surfaces of silicon and stainless steel with pencils of different hardness (HB, 4B, and 9B) in terms of analytical performance in quantification of As and Fe in water. We deposited 1 μL of aqueous solutions of As and Fe on these substrates over a concentration range of 6-1000 ppm, and then dried the samples with a conventional hair drier. LIBS spectra were collected and calibration curves for each of these cations were built from the areas of the corresponding spectroscopic peaks. In this context we discuss the influence of phenomena such the matrix effect, self-absorption, and self-reversal, upon the non-linear behavior of the calibration curves. We introduce a setup to discuss qualitatively the influence of these two last effects by retro-reflection of the spark light into the LIBS plasma. Suitable calibration curves are obtained for these two elements on the pencil-scratched-silicon substrate. As expected the pencil-scratched-steel substrate does not turn out to be convenient to analyze iron because the elementary constitution of steel already contains iron. The data to build the calibration curves were treated and modeled in agreement with existing literature. This work will improve the usability of previous methods for future industrial and environmental applications. © Sociedad Española de Óptica.