Electric Field-Assisted Laser-Induced Breakdown Spectroscopy for Enhanced Detection of Heavy Metals in Soil

Laser Induced Breakdown Spectroscopy (LIBS) is a versatile technique for rapid, in-situ elemental analysis of soil contaminants. However, LIBS sensitivity for trace heavy metals is limited by transient plasma dynamics and matrix effects. This study investigates the application of an externally applied electric field during LIBS plasma formation to enhance the detection of chromium (Cr), manganese (Mn), and strontium (Sr) in soil contaminated by industrial waste. Results show that the external electric field (120 V/mm) significantly increased plasma temperature from 11,787 K to 15,415 K and increased the electron density. As a result, the emission intensities of Cr I (520.45 nm), Mn I (403.08 nm), and Sr I (460.71 nm) spectral lines were enhanced by a factor of 3–5. The limits of detection (LODs) showed substantial improvement with the application of the external E-field. Additionally, the electric field extends plasma lifetime, which leads to improved signal stability. These findings establish electric field-assisted LIBS (EF-LIBS) as a promising enhancement approach for further instrumentation development, and it may offer a relatively practical pathway for improved sensitivity in field-compatible LIBS systems, supporting its potential application in the soil analysis.