Quantification of Key Elements in Lithium Brines by ICP-OES

Importance of Topic

The transition to renewable energy and the rapid expansion of electric vehicle markets have made lithium a critical raw material for high-energy-density rechargeable batteries. Brine extraction of lithium, especially from high-salinity sources, poses significant analytical challenges due to elevated total dissolved solids (TDS), variable matrices, and potential particulates that can impair plasma stability and sample introduction systems.

Objectives and Overview

This study demonstrates a fast and robust approach to quantify key elements (Li, B, Ca, Mg, Mn, Si, K, Sr) in lithium-rich brines using the Agilent 5800 Vertical Dual View (VDV) ICP-OES equipped with an AVS 7 switching valve. The primary goals were to optimize sample throughput, maintain analytical accuracy across a wide concentration range, and minimize instrument maintenance.

Methodology and Instrumentation

Real brine samples (15–25% NaCl) were diluted at 1:20 and 1:100 in 5% HNO₃. An internal standard mixture of Sc, In, and Rb was introduced in-line via the AVS 7 valve to correct for viscosity variations and easily ionized element interferences. MultiCal software was employed to combine multiple calibration ranges for Mg and Ca to extend the linear dynamic range without sacrificing sensitivity.

• ICP-OES: Agilent 5800 Vertical Dual View
• Autosampler: SPS 4 with AVS 7 switching valve
• Internal standards: Sc (5 ppm), In (25 ppm), Rb (75 ppm)
• Detector: Vista Chip III for full wavelength coverage and MultiCal functionality

Main Results and Discussion

Analysis of three representative brine samples showed excellent reproducibility across both dilutions, with relative percentage differences (RPD) from 0.2% to 7.4%. The AVS 7 valve effectively reduced solids loading and carry-over, decreasing torch fouling and extending maintenance intervals. Continuous measurement of 120 samples exhibited no drift, plasma quenching, or clogging. The MultiCal approach seamlessly covered major and trace elements, avoiding repeated remeasurements.

Benefits and Practical Applications

Key advantages of the optimized method include:

• High throughput: 73 s sample-to-sample cycle time
• Robust performance with high TDS matrices
• Extended linear dynamic range for major elements via MultiCal
• Reduced maintenance and consumable costs due to AVS 7
• Reliable quantification for QA/QC in lithium extraction workflows

Future Trends and Opportunities

As lithium demand continues to rise, analytical protocols will evolve toward even faster screening and on-site monitoring. Integration of automated valve systems with real-time diagnostics, expanded use of multi-matrix calibration techniques, and coupling with advanced data analytics will further streamline brine analysis. Portable or field-deployable ICP-OES systems may emerge for in-situ resource evaluation.

Conclusion

The Agilent 5800 ICP-OES with AVS 7 and MultiCal delivers a fast, accurate, and low-maintenance solution for complex lithium brines. This workflow balances sensitivity, dynamic range, and operational efficiency, supporting the growing needs of battery-grade lithium production.

Reference

• Agilent Technologies. Quantification of Key Elements in Lithium Brines by ICP-OES. Application Brief 5994-4868EN, July 2022.