Plasma Image-Calibrated Double-Pulse Laser-Induced Breakdown Spectroscopy for High-Precision Quantification of Light Rare Earth Elements in Geological Matrix

As critical strategic resources for modern high-tech industries, accurate quantitative analysis of light rare earth elements (LREEs) holds significant importance in resource exploration, new energy materials research, and ecological monitoring. Traditional laser-induced breakdown spectroscopy (LIBS) suffers from matrix effects and spectral interference, posing challenges to achieve high quantitative accuracy in low-concentration LREEs detection in geological matrices. This study proposes a novel double-pulse LIBS (DP-LIBS) spectral calibration method integrating plasma imaging information. DP-LIBS was employed to enhance the spectral intensity of trace elements in natural rock samples. An ICCD camera was used to capture plasma images simultaneously with spectral acquisition. By establishing a correlation between the plasma temperature and image brightness, correction factors were calculated to calibrate the original signals. Quantitative analysis of the calibrated spectra reveals the determination coefficients (R²) for LREEs reached up to 99.86%, the root-mean-square error (RMSE) was as low as 0.10, and the optimal relative standard deviation (RSD) was 0.95% (Pr). After calibration, the limits of detection (LODs) for La, Ce, Pr, Nd, Eu, and Sm were 6.24, 9.56, 4.25, 1.27, 0.57, and 3.58 ppm, respectively. In addition, spike-and-recovery experiments were conducted, and the recovery values of the six LREEs were generally within the range of 92.04 to 119.18%. In summary, this spectral calibration method overcomes the limitations of traditional LIBS in ultraprecise quantitative analysis of trace elements, effectively suppresses matrix effects, and provides a new paradigm for the accurate analysis of LREEs in complex matrices.