Enhanced emission spectra from flame-assisted LIBS for high-sensitivity detection of Pb in water

Laser-induced breakdown spectroscopy (LIBS) is a powerful technique for detecting and analyzing material elements through plasma emission generated by high-power laser pulses. In this study, the enhancement of Cu plasma emission spectra using flame-assisted LIBS was investigated. The plasma temperature and electron number density were calculated to understand the enhancement mechanism. Additionally, the dry droplet pretreatment method was combined with flame-assisted LIBS to quantitatively analyze trace amounts of heavy metal Pb in aqueous solutions. A calibration curve for Pb was established, and the limits of detection (LOD) for Pb with and without flame assistance were determined. The LOD without flame was 15.120 ng mL⁻¹, while the LOD with flame assistance was significantly lower at 0.741 ng mL⁻¹, demonstrating a 20-fold improvement. The R² values of the calibration curves with and without flame assistance were 0.987 and 0.999, respectively. These results confirm that the flame-assisted method significantly enhances LIBS signal intensity, and the combination with dry droplet pretreatment improves the sensitivity for analyzing trace metal elements in water.