Rapid quantitative analysis of palladium in ores using laser-induced breakdown spectroscopy assisted with laser-induced fluorescence (LIBS-LIF)

This paper discusses the use of conventional LIBS and LIBS-LIF techniques to measure trace amounts of palladium in solid ore samples. Combination of excitation/fluorescence of Pd lines as well as plasma creation conditions were studied to optimize the performances of LIBS-LIF for spectrochemical analysis of palladium. Calibration curves were established using pressed powder pellets of reference materials doped with a solution of palladium. The optimum single-shot limit of detection (LoD) of palladium obtained by the conventional LIBS technique for our setup (Pd 348.12 nm line) was 10 ppm or 1 ppm using 100 laser shots. In contrast, LIBS-LIF (Pd 276.31 nm line for excitation and Pd 351.69 nm line for fluorescence) gave an LoD of 160 ppb for a single laser shot or 16 ppb using 100 laser shots. In addition, LIBS-LIF can resolve the palladium spectral lines in iron-bearing mineral matrices, which is problematic with conventional LIBS due to spectral interference. It is demonstrated for the first time that LIBS-LIF could enable the mining industry to rapidly measure trace amounts of palladium at sub-ppm levels per laser shot in solid ore samples without any sample preparation. The obtained results are a proof of concept of the LIBS-LIF technique feasibility for the quantitative analysis of palladium in ore samples. They show that LIBS-LIF could be a good candidate for real time analysis of palladium in ore samples in terms of standoff capabilities, sensitivity and speed of analysis.

Automated summary

This paper discusses the use of conventional LIBS and LIBS-LIF techniques for measuring trace amounts of palladium in solid ore samples. The study optimized the performances of LIBS-LIF for spectrochemical analysis of palladium by studying the combination of excitation/fluorescence of Pd lines and plasma creation conditions. Calibration curves were established using reference materials doped with a palladium solution. The results demonstrated that LIBS-LIF could rapidly measure sub-ppm levels of palladium in solid ore samples without any sample preparation, and it could resolve the spectral interference which is problematic with conventional LIBS.