Laser-induced breakdown spectroscopy of trace metals

The detection and quantification of light elements and heavy metals within liquid samples and those produced by acid dissolution of solids are pertinent to industrial processing, environmental monitoring and waste treatment [1–5]. To-date, laser-induced breakdown spectroscopy (LIBS) has been tested with limited success. Dissolved gases, particulate material and nucleation-induced bubbles produced by prior laser pulses can lead to misfocusing of the laser beam and can also serve as breakdown sites prior to the laser beam focus [1–3,6,7]. Additionally, the high local density within the liquid leads to rapid quenching which prohibits temporally selective detection, high collision rates which broaden spectral transitions and confines the plasma emission spatially rendering spatially selective detection problematic. Given these inherent difficulties, in-situ LIBS analysis of liquids has not been widely sucessful witfi detection limits in the range of 1 -100 ppm for light metals [1,3-6,8-11], As a result, even fewer studies have investigated detection of heavy metals [1-3,6] with Hg being reported undetectable at 1000 ppm [3].