Overcoming Matrix Challenges in TOC Quantification of Reinjected Lithium Brines

As global demand for lithium intensifies, Direct Lithium Extraction (DLE) has emerged as a more sustainable alternative to traditional solar evaporation methods. However, the reinjection of treated brines into underground reservoirs requires stringent monitoring of Total Organic Carbon (TOC) to ensure environmental compliance. Due to the challenging matrix (high total dissolved solids (TDS) and particulates), it is common to utilize large dilution factors which can sacrifice sensitivity. There is also the risk of experiencing higher rates of component consumption. To combat increased maintenance intervals, a salt kit was utilized with the multi N/C 3300 high-temperature combustion analyzer. This configuration, with wide inner diameter tubing and a split calibration strategy, enabled excellent matrix tolerance. The system achieved a low detection limit of 40.95 µg/L and high precision (RSD < 3%) across a broad concentration range (0.5–500 mg/L), demonstrating its suitability for routine TOC analysis in complex lithium brine matrices.