A simple method for elemental analysis of liquids in sprayed microdroplets by laser-induced breakdown spectroscopy

Abstract

The combination of paper spray with laser-induced breakdown spectroscopy (PS-LIBS) was used to analyze trace elements in aqueous solutions. The analysis of sprayed charged microdroplets eliminates the experimental challenges of bulk liquid analysis, such as splashing and surface ripples, which often affect LIBS sensitivity. In contrast to other electrospray techniques, PS is a simple and robust method that allows for the direct loading of liquid samples onto paper. Its performance is largely dependent on the quality of the spray plume, influenced by factors like paper shape, tip angle, spray voltage, and solvent composition. The cut angle of the paper tip significantly influences the spray plume and total ion current, with sharper tips being more efficient at generating sprayed microdroplets. The detection limits for Na, K, and Cr – 11.1 mg L⁻¹, 28.9 mg L⁻¹, and 67.9 mg L⁻¹, respectively, – are in line with typical values from other LIBS experiments on liquid samples. These experimental results indicate that PS-LIBS is a promising technique for the in situ analysis of trace elements in liquid samples.