Field demonstrations of a direct push FO-LIBS metal sensor

Area of Science:

• Environmental Science
• Analytical Chemistry
• Geochemistry

Background:

• Real-time, in-situ soil metal analysis is crucial for environmental monitoring.
• Traditional lab methods are time-consuming and costly.
• Existing field methods may lack accuracy due to soil matrix variations.

Purpose of the Study:

• To develop and demonstrate a direct push, fiber optic laser-induced breakdown spectroscopy (FO-LIBS) sensor probe.
• To enable real-time, in-situ measurement of metals in soils.
• To assess the sensor's performance and accuracy in diverse soil conditions.

Main Methods:

• A direct push FO-LIBS sensor probe was constructed.
• Site-specific calibration curves were generated using spiked soil samples.
• Techniques including extra laser pulses and adjusted power densities were used to compensate for moisture.
• Peak areas were normalized to correct for plasma volume variations.

Main Results:

• The FO-LIBS sensor's response is influenced by soil matrix properties (grain size, composition, water content).
• Site-specific calibration effectively compensates for variations in soil matrix conditions.
• Normalization of spectral peak areas corrects for variability in plasma volume.
• Field demonstrations showed good agreement between in-situ FO-LIBS and laboratory ICP results.

Conclusions:

• The FO-LIBS sensor serves as a valuable semi-quantitative field screening tool for soil metals.
• The developed calibration and normalization methods enhance the reliability of in-situ measurements.
• The sensor demonstrates potential for rapid environmental site assessment.