Detection of Low Lithium Concentrations Using Laser-Induced Breakdown Spectroscopy (LIBS) in High-Pressure and...

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Geochemistry

Background:

• Accurate elemental analysis is critical for understanding marine environments.
• Deep ocean conditions, such as those near hydrothermal vents, present unique analytical challenges.
• Laser-induced breakdown spectroscopy (LIBS) offers potential for in-situ elemental determination.

Purpose of the Study:

• To investigate the influence of pressure, solution flow rate, and laser pulse rate on lithium (Li) determination using LIBS.
• To assess the performance of LIBS for Li analysis in aqueous and saline solutions under simulated deep ocean conditions.
• To establish optimal parameters for sensitive and accurate Li detection in challenging environments.

Main Methods:

• Utilized laser-induced breakdown spectroscopy (LIBS) to analyze lithium solutions.
• Varied experimental conditions including pressure (ambient to 210 bar), solution flow rate (static to 6 mL/min), and laser pulse rate (2-10 Hz).
• Analyzed lithium concentrations ranging from 0-40 mg/L in both pure water and 2.5% NaCl solutions.

Main Results:

• Calibration curve sensitivity significantly increased with pressure, especially under flowing conditions (10-18% increase).
• A synergistic effect between high pressure and flow rate was observed, enhancing Li determination sensitivity.
• Increased laser pulse rate from 2 to 10 Hz boosted sensitivity by 26-31%.
• Achieved detection limits of ~40 µg/L for Li in pure water and ~92 µg/L in 2.5% NaCl under optimal high-pressure, flowing conditions.

Conclusions:

• LIBS is a robust technique for determining lithium in deep ocean environments.
• Optimizing pressure, flow rate, and pulse rate enhances LIBS sensitivity for lithium analysis.
• The findings support the application of LIBS for in-situ monitoring of elements in extreme marine settings like hydrothermal vents.