laser-induced breakdown spectroscopy; borate fusion; bauxite; sample preparation; matrix-match; pellet;PLASMA-MASS SPECTROMETRY; ELEMENTAL ANALYSES; LIBS; SAMPLES; GEOCHEMISTRY; FUSION

Due to matrix interference and sample particle size effects, some of the most important and difficult issues in laser-induced breakdown spectroscopy (LIBS) analysis are the calibration and quantitative measurement of a complex matrix. This study proposes the use of borate fusion as an alternative sample preparation procedure for the quantitative measurement of Al, Fe, Si and Ti in bauxite by LIBS. Analytical calibration curves were made using bauxite certified reference materials (CRM), and the precision and accuracy of the methods were evaluated by analysing an additional bauxite CRM, using two different approaches: pressed powder pellets and fused glass beads. The borate fusion method was the most suitable sample preparation technique, since particle size effects and matrix interference could be minimised, obtaining better linearity on the analytical calibration curves (r(2)), and more accurate and more precise results for bauxite analysis.