Laser-induced breakdown spectroscopy analysis of water solutions deposited on PTFE surface: Influence of copper oxide nanoparticles and NELIBS effect

The analytical potential of LIBS for the analysis of liquid solutions was evaluated using two experimental setups, one based on a TEA CO2 laser and the other in which Nd:YAG laser was used. Polytetrafluoroethylene (PTFE) was used as a substrate on which a 10 mu L drop of analyte solutions with different concentrations of analyte elements, Be, Cr, Ni, Co, Pb, Tl, and V, were deposited and dried. The samples were deposited either directly on the PTFE or over the pre-deposited layer of copper oxide nanoparticles to study the influence of nanoparticles (NPs) on the ablation and plasma excitation. The obtained results imply that the presence of Cu oxide NPs does not significantly affect the analytical performance of LIBS based on TEA CO2 laser for analysis of solutions. At the same time, it was shown that plasma created by TEA CO2 laser radiation efficiently excited ablated material, making metal elements detectable in the sub-ppm concentration range. On the other hand, Cu oxide NPs significantly influence the formation and the analytical properties of plasma induced by Nd:YAG laser. Without the presence of NPs, the intensities of analyte lines were very low, unsuitable for spectrochemical analysis. At the optimal surface concentration of NPs, 0.36 mg/cm(2), the intensity of analyte lines was increased more than ten times. Limits of detection of Be and Cr were 5.3 ppb and 33 ppb, with good linearity of curves of growth.