To address the prevalent issues of low signal sensitivity and severe spectral interference encountered during the detection of lithium in high-magnesium background salt lake brines, a quantitative analytical method based on functionalized membrane-assisted solid-phase transformation combined with Laser-Induced Breakdown Spectroscopy (LIBS) is proposed. This method aims to circumvent the plasma splashing effect associated with direct liquid-phase ablation by converting lithium ions in the liquid phase into solid-phase particles for enrichment and subsequent detection. An EDTA/chitosan synergistically modified membrane was employed as the enrichment medium; through the synergistic effects of multidentate complexation and electrostatic adsorption, the capture efficiency of carbonate particulates was significantly enhanced, achieving a lithium precipitation retention rate of 95.6%. To further mitigate spectral signal fluctuations, a multistage homogenization sample preparation protocol—comprising chemical precipitation, thermal treatment, mechanical grinding, and homogeneous mixing—was established. Additionally, a 3D-printed clamping-limiting module was designed to stabilize the optical path configuration, thereby ensuring high consistency in laser focusing position and sample surface planarity across different measurement batches and providing reliable hardware assurance for signal acquisition. During the spectral acquisition stage, the laser operating voltage parameters were optimized, achieving an effective balance between plasma signal intensity and signal-to-noise ratio under the designated laser operating conditions. Experimental results demonstrate that the method exhibits robust resistance to matrix interference under typical high-magnesium matrix conditions. A stable linear quantitative model was established within the lithium mole fraction range of 10%-90%, yielding a coefficient of determination (R2) of 0.985. The findings indicate that the proposed “liquid-to-solid transformation” strategy effectively mitigates the adverse effects of complex liquid matrices on LIBS detection, thereby providing reliable technical support for the on-site rapid detection and assessment of lithium resources in salt lakes.
He et al. (Mon,) studied this question.