Detection of lead in soil implying sample heating and laser-induced breakdown spectroscopy.

The emission line intensities enhancement and sensitivity of laser-induced breakdown spectroscopy (LIBS) has been a subject of great interest for the last several years to improve the detection of the trace elements in soil and other environmental samples. Among several other methodologies, LIBS of the heated targets is emerging as one of the effective techniques to achieve the objective. We have investigated the effect of target heating (room temperature, 100°C, and 200°C) on the emission enhancement and plasma parameters of the laser-produced plasma on the soil sample containing 80 ppm lead. In addition, the limit of detection (LOD) of lead in soil has been determined at a fixed target temperature (200°C) and with varying lead concentration (20 ppm, 80 ppm, and 100 ppm) in the soil samples. With increasing the target temperature, not only do the emission line intensities, the excitation temperature, and electron number density increase, but also the spectral lines of Pb emerge, which were absent in the soil spectra recorded at room temperature. The limit of detection of lead in LIBS of the heated soil target has been determined as 3.8 ppm. This study reveals the potential application of the LIBS of a pre-heated target for the detection of lead with an improved LOD in the environmental sample.