Application of laser-induced breakdown spectroscopy to in situ analysis of liquid samples

A realization of laser-induced breakdown spectroscopy for real-time, in situ and remote analysis of trace amounts in liquid samples is described, which is potentially applicable to the analysis of pollutants in water in harsh or difficult-to-reach environments. Most of the measurements were conducted using a fiber assembly that is capable of both delivering the laser light and collecting the light emitted from the micro plasma, up to about 30 m from the target area. Alternatively, a telescopic arrangement for line-of-sight measurements was employed, with a range of 3 to 5 m. For internal standardization and the generation of concentration calibration curves, reference lines of selected elements were used. In the majority of cases calibration against the matrix element hydrogen was employed using the H?, H?, and H? lines, but also spiking with selected reference species was utilized. In order to provide high reliability and repeatability in the analyses, we also measured plasma parameters such as electron density, plasma temperature, and line- shape functions, and determined their influence on the measurement results. Numerous elements, including a range of toxic heavy metals, have been measured over a wide range of concentrations (Al, Cr, Cu, Pb, Tc, U, and others). Limits of detection usually were in the range of a few parts per million; for several elements even lower concentrations could be measured.