A standardized method for characterization of matrix effects in laser-induced breakdown spectroscopy

The dried droplet method is proposed as a way of characterizing matrix effects in LIBS with a standardized approach. This method was introduced first in the field of LA-ICPMS for quantitative analysis of solids. It consists in depositing a droplet of an iron-containing solution on the sample surface and ablating the dry residue. Then, iron lines are used for spectroscopic diagnoses of the plasma. Along with white-light profilometry analysis for ablation craters measurements, this aims to accurately determine differences of ablated mass, electron excitation temperature and number density, including for pure metals. In this paper, we check that the presence of the dry residue does not influence those three factors. Then, the dried droplet method is applied to 14 pure metals. Results show that the number of ablated atoms varies by a factor of 25, while for the electron excitation temperature the maximum gap between the 14 metals is approximately 2000 K, i.e. a relative variation of ~30%. As for the electron number density, it could be estimated for only 6 metals and it varies within the measurement uncertainty between 6 and 8 1016 cm−3. [Display omitted] •A dried droplet method is proposed to characterize matrix effects in a laser-produced plasma with a standardized approach•Iron lines from an iron solution residue on the sample surface are used for Boltzmann plots and Stark broadening measurements•The deposit does not affect the ablated mass, the electron excitation temperature Te and number density ne•Optimized with Al and Cu alloys, then applied to the characterization of matrix effects for 14 pure metals ablated at 266 nm•The largest differences are observed for the number of ablated atoms. They are much less pronounced for Te and ne