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.