Optimization of carbon-based thin film microextraction supports for simultaneous detection of heavy metals using LIBS

One of the most versatile and effective methods to improve LIBS analysis of liquids is Thin Film Microextraction (TFME). This approach generally uses carbon-based adsorbent films to extract analytes from a liquid sample and bind them into a solid matrix, which is ideal for LIBS. In a previous work, we demonstrated the feasibility of TFME supports based on graphene prepared by Pulsed Laser Ablation in Liquid (PLAL) for LIBS analysis. In this paper, we optimized the preparation of such supports for the analysis of heavy metals in aqueous samples (i.e. chromium, lead and nickel), by analyzing both standard solutions and real samples. The feasibility of coupling TFME with NELIBS approach was also exploited. The procedure was applied to the analysis of both mineral water and well water samples. We obtained a standardized procedure for the extraction of three analytes (Pb, Cr and Ni) and estimated LOD values in spiked mineral water of the order of 0.6 mg/L for LIBS and 0.2 mg/L for NELIBS.