WCPS: Elemental Analysis of Brine Samples used for Lithium Extraction

Importance of the Topic

Lithium plays a central role in modern energy storage, powering everything from portable electronics to electric vehicles. As demand for lithium-ion batteries continues to rise, efficient extraction and quality control of lithium from brine resources become critical. High-throughput, accurate elemental analysis of these complex matrices supports process optimization, cost reduction and ensures battery-grade purity.

Objectives and Study Overview

This study aimed to develop and validate a rapid, robust method for simultaneous determination of key elements—B, Ca, Li, Mg, Mn, Si, K and Sr—in high‐salinity brine samples (15–25% NaCl) using ICP-OES. Specific goals included:

• Establishing reliable sample preparation and internal standard correction.
• Evaluating instrument stability and detection limits in demanding matrices.
• Assessing method accuracy via spike recovery and repeatability across multiple real brine samples and dilutions.

Methodology and Instrumentation

Sample Preparation:
A series of seven brine supernatants were gravimetrically diluted at 1:20 and 1:100 in 5% HNO₃. A bespoke internal standard mixture (Sc, In, Rb) was introduced in-line to correct for physical and ionization interferences.

Instrumentation:
The Agilent 5800 Vertical Dual View (VDV) ICP-OES, equipped with an AVS 7 switching valve and SPS 4 autosampler, was used. Key components and settings included:

• SeaSpray nebulizer, double-pass cyclonic spray chamber, 1.8 mm I.D. demountable injector.
• Radial viewing mode, RF power 1.45 kW, plasma and auxiliary flows of 13.5 and 1.6 L/min.
• Three replicates per sample, 5 s read time, 20 s stabilization delay.
• Software aids: IntelliQuant Screening for semiquantitative profiling, MultiCal for extended dynamic range, and Early Maintenance Feedback (EMF) diagnostics.

Main Results and Discussion

Long-Term Stability:
Over 360 measurements spanning 10 hours without recalibration, recoveries for all analytes remained within ±3%, and QC samples passed consistently.

Method Detection Limits (MDLs):
MDLs determined in 1% NaCl spiked at 20 ppb ranged from 0.0006 mg/L (Mn) to 0.129 mg/L (K), demonstrating low detection thresholds even in saline matrices.

Spike Recovery and Accuracy:
Real brine samples diluted 1:20 and spiked at 1 ppm showed recoveries between 91% and 105% for target elements, confirming method accuracy.

Quantitative Performance:
Analysis of three brines at two dilution factors yielded relative percentage differences (RPD) below 7.5% for all elements. This indicates excellent precision across concentration ranges from high-ppb to percent levels.

Dynamic Range and Calibration:
Utilizing multiple wavelengths per element and the MultiCal feature enabled a broad linear dynamic range, reducing the need for repeated dilutions and reruns.

Benefits and Practical Applications

The developed method offers:

• Robust handling of high total dissolved solids, minimizing sample carryover and maintenance.
• Streamlined workflow through in-line internal standard addition and automated software tools.
• Wide dynamic range suitable for elements present from trace to percent concentrations.
• Reliable QC metrics ensuring consistent, reproducible results for battery-grade brine analysis.

Future Trends and Potential Applications

Emerging directions include integration of real-time monitoring with online switching valves, coupling with machine learning for predictive maintenance and data interpretation, and expansion to other high-salinity resources such as geothermal fluids or seawater desalination by-products. Advances in detector technology and software algorithms will further enhance sensitivity and throughput.

Conclusion

The Agilent 5800 VDV ICP-OES with an AVS 7 switching valve provides a fast, accurate and low-maintenance solution for multi-elemental analysis of lithium-rich brines. The method delivers reliable quantification across challenging matrices, supporting quality control and process optimization in lithium extraction.

References

1. Xu C., Dai Q., Gaines L., et al. Future Material Demand for Automotive Lithium-Based Batteries. Commun Mater. 2020;1:99.
2. Agilent Technologies. Reduce Costs and Boost Productivity with the Advanced Valve System (AVS) 6 or 7 Port Switching Valve System. Publication 5991-6863EN.
3. Agilent Technologies. Agilent IntelliQuant Screening: Smarter and Quicker Semiquantitative ICP-OES Analysis. Publication 5994-1518EN.
4. Agilent Technologies. Quantification of Key Elements in Lithium Brines by ICP-OES. Publication 5994-4868EN.