Salinity effects on elemental analysis in bulk water by laser-induced breakdown spectroscopy

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Environmental Science

Background:

• Underwater laser-induced breakdown spectroscopy (LIBS) is a promising technique for elemental analysis in aquatic environments.
• Understanding the influence of environmental factors, such as salinity, is critical for accurate LIBS measurements.

Purpose of the Study:

• To investigate the effects of varying salinity levels (2‰ to 50‰) on underwater LIBS plasma characteristics and spectral data.
• To assess the impact of salinity on the performance and detection capabilities of underwater LIBS.

Main Methods:

• Utilized spectroscopic analysis to observe plasma emission intensities of atomic and ionic lines.
• Employed fast imaging techniques to analyze plasma morphology, temperature, and electron density.
• Generated calibration curves at different salinities to evaluate detection limits.

Main Results:

• Increased salinity led to enhanced atomic line emission and suppressed ionic line emission.
• Signal-to-background ratios decreased with rising salinity, while signal-to-noise ratios showed irregular changes.
• Higher salinity resulted in brighter, longer plasma with increased plasma temperature and electron density.
• Calibration curves demonstrated that high salinity does not inherently limit LIBS detection capabilities.

Conclusions:

• Salinity significantly influences underwater LIBS plasma properties and spectral output.
• The findings provide essential insights for optimizing LIBS parameters in diverse marine and estuarine environments.
• This research supports the broader application of LIBS for in-situ chemical analysis in oceanic settings.