Sensitive detection of metals in water using laser-induced breakdown spectroscopy on wood sample substrates

Water contaminated with toxic heavy metals can be a great risk to humans. Laser-induced breakdown spectroscopy (LIBS) is a promising candidate to monitor heavy metals in aqueous solutions on site, but the sensitivity is still a major problem. To perform sensitive analysis of analyte metals in aqueous solutions with LIBS, a thin wood sample substrate was used as a liquid absorber to transform the liquid sample analysis to a solid sample analysis. We focus on investigating the performance of this technique using different laser wavelengths (266, 532, and 1064 nm) with a low pulse energy (<5 mJ) and a different number of shots (from 10 to 1000). We demonstrate that a limit of detection of 30 ppb can be achieved using low energy pulses with a 1000 shot accumulation. This technique provides a potentially simple approach for a portable micro LIBS system to monitor water samples.