Quantitative analysis of trace elements in liquid samples using laser induced breakdown spectroscopy

The present study demonstrates the suitability of the drop-casting technique for the determination of trace elements in liquids using laser induced breakdown spectroscopy (LIBS). In the present work, high-power laser shots are irradiated on the surface of a copper target to create a crater on it. Sample solutions containing trace metal elements, Na, Mg, Ca, Al, Fe and Zn are drop casted into the laser produced craters to obtain a homogeneous sample distribution. The sample is then ablated to form plasma, emissions from which are analysed to obtain a quantitative estimate of trace elements. The analytical accuracy of around 8% relative standard deviation (RSD) is achieved for the drop-casting of 3 µl of sample solution into the crater. Absolute detection limits of 0.06 mg/L for Na, 0.09 mg/L for Ca, 0.06 mg/L for Mg, 0.05 mg/L for Al, 0.23 mg/L for Fe and 0.11 mg/L for Zn are obtained. The proposed approach has been applied to estimate trace elements in liquid samples, including river water and multi-element standard solution. The present drop-casting LIBS technique has been validated using inductively coupled plasma optical emission spectroscopy (ICP-OES) technique and the results show a good resemblance.