Direct Determination of Lithium in Brine Solutions Using a Liquid-Phase Laser-Induced Breakdown Spectroscopy Instrument

Abstract

Laser-induced breakdown spectroscopy has become a promising method for rapid elemental analysis; however, application of LIBS directly to liquid solutions remains technically challenging due to plasma instability and matrix effects. In this study, a liquid-phase LIBS system featuring sample introduction via a nebulizer-based aerosol was evaluated for direct measurement of lithium in synthetic brine solutions. A synthetic brine sample matrix was prepared by saturating a 1% HNO3 solution with sodium chloride. The brine was spiked with various analytes at concentrations expected in natural brine solutions of interest for modern industrial purposes, with a focus on Li. Lithium emission at 670.8 nm was clearly detected, with a detection limit of 0.3 mg L−1. An evaluation of calibration strategies, including external calibration, internal standardization, and standard addition, showed that matrix effects significantly impact measurement accuracy, as expected of any analytical instrumentation setup. Incorporation of standard addition allowed for the liquid-phase LIBS system to successfully quantify lithium in synthetic brine solutions without additional sample preparation or dilution. These findings suggest that, with proper sample introduction and calibration, liquid-phase LIBS analysis can be a quick and portable alternative to traditional lab techniques for lithium detection and process monitoring in complex brines.