The application of laser-induced breakdown spectroscopy (LIBS) to the chemical analysis of low-ash lignite has been investigated. A Nd:YAG laser (λ = 1064 nm) is used to induce emission from the ash-forming components, which is then spectrally resolved and analyzed. LIBS analyses of five inorganic components of lignite were shown to be reproducible between sample pellets at a 95% confidence level. Detection limits (in ppm) on an as-received basis of 60 (Ca and Al), 70 (Na), 90 (Fe), and 200 (Mg and Si) were obtained from a study of 30 lignite samples, each of which was interrogated by 300 laser pulses.
Fiona J. Wallis, Bruce L. Chadwick, and Richard J. S. Morrison, "Analysis of Lignite Using Laser-Induced Breakdown Spectroscopy," Appl. Spectrosc. 54, 1231-1235 (2000)