A solid substrate based on clay minerals for sampling organic liquids in molecular LIBS analysis

LIBS is an analytical technique for direct analysis, capable of performing elemental, molecular and isotopic characterization. This technique involves the physical processes of ablation and plasma formation by the incidence of high-energy laser pulses. The direct analysis of liquid samples is challenging due to the occurrence of splashes that impairs the measurement in many aspects. In this work, an inorganic solid substrate consisting of a bentonite/sepiolite composite (70/30 wt%) is described as a support for organic liquids in molecular LIBS analysis. The substrate allowed molecular LIBS measurements of solvents, fuels and even aqueous solution with minimal spectral interference and made it possible to identify molecular radical emissions (CN and C 2 ). Therefore, the proposed substrate is believed to be an alternative material for sampling organic liquids for molecular LIBS analyses. A clay mineral substrate based on a mixture of bentonite and sepiolite allows the direct molecular LIBS analysis of flammable liquids, such as toluene, gasoline and diesel.