Improving the quantitative accuracy of one-point calibration LIBS based on magnetic confinement of self-absorption correction

Abstract

Laser-induced breakdown spectroscopy (LIBS) is widely applied in elemental quantitative analysis due to its rapid response, in situ detection, and simultaneous multi-element measurement capabilities. However, self-absorption effects, especially in high-concentration samples or under resonant transition conditions, often cause nonlinearity in calibration curves, significantly compromising the accuracy of quantitative analysis. To address this issue, this study proposed a combined approach integrating magnetic field confinement with one-point calibration LIBS (OPC-LIBS) to mitigate self-absorption effects and thereby improve quantitative accuracy. Six certified standard aluminum alloy samples were selected to evaluate the method. The impact of the applied field on plasma properties and analytical performance was studied for both the major matrix element (Al) and trace alloying constituents (Mg, Cu, Fe, and Ni). The experimental results demonstrated that magnetic field confinement enhanced spectral intensity and electron temperature, while increasing electron density—a signature of plasma confinement. This led to a more stable and uniform plasma, which effectively decreased self-absorption. In terms of quantitative performance, magnetically confined OPC-LIBS exhibited higher linearity and accuracy compared to conventional OPC-LIBS. Moreover, the linearity and accuracy varied among different elements. Under optimal conditions, the coefficient of determination (R²) between the predicted and certified concentrations of Al and Fe increased from 86.67% and 97.57% to 98.89% and 99.85%, while the average relative error (ARE) decreased from 0.21% and 8.99% to 0.05% and 2.99%, and the root mean square error of calibration (RMSEC) dropped from 0.20 wt% and 0.1 wt% to 0.05 wt% and 0.02 wt%, respectively. These results confirm the synergistic advantage of combining magnetic field confinement with OPC-LIBS for self-absorption correction and precise quantitative analysis, providing an effective technical pathway for high-precision elemental detection in complex matrices.