Analysis of Rock Powders by Laser-Induced Breakdown Spectroscopy Combined with the Graphite Doping Method

• Published in: Journal of applied spectroscopy 2020-11, Vol.87 (5), p.919-924
• Main Authors: Jiа, J. J., Hongbo, F., Huadong, W., Fengzhong, D., Zhirong, Z.
• Format: Article
• Language: English
• Subjects: Analytical Chemistry; Atomic/Molecular Structure and Spectra; Graphite; Methods; Physics; Physics and Astronomy; Powders; Spectrum analysis
• ISSN: 0021-9037; 1573-8647
• DOI: 10.1007/s10812-020-01089-w

The analysis of geological samples using laser-induced breakdown spectroscopy (LIBS) is strongly affected by matrix effects. To investigate the improvement of matrix effects by the graphite doping method, rock powder was mixed with graphite powder and pressed into pellets. Four groups of samples with the same graphite content were prepared from a mixture of seven different rock powders and four graphite powders (0, 25, 50, and 75 wt.%). To reduce some of the pulse-to-pulse fluctuations, the internal standardization method was adopted. Four sets of calibration curves of Ca and Mg were prepared using pellet samples with the same graphite content. The influence of graphite content on laser-induced plasma temperature and electron density was further investigated. The coefficients of determination (R 2 ) of the calibration curves after doping graphite are larger than those without doping, and the stability of the spectral intensity, plasma temperature, and electron density after doping are also improved. In particular, when the doping percentage is 50%, the matrix effect is significantly improved. The results show that the graphite doping method has great potential for improving the matrix effects of LIBS in the analysis of rock powder samples.