Rapid analysis of phosphate slurries and pressed pellets using laser-induced breakdown spectroscopy

This paper demonstrates the capabilities of laser-induced breakdown spectroscopy (LIBS) to perform quantitative multi-elemental analysis in phosphate slurries and pressed pellets. Fourteen phosphate powder samples were used in this study. 30 ml (12-13 g) of each phosphate powder sample were pelletized using an automated hydraulic press, and eleven slurries having a solid density of 30% (w/v) were prepared by mixing an appropriate quantity of powder and water. Samples were then analyzed by the Dual-LIBS instrument. A calibration model was generated for several elements contained in the samples, namely phosphorus, aluminum, iron, carbon, silicon, and magnesium, using a multivariate linear regression (MLR) method. The accuracy and reproducibility of the multivariate model were evaluated using independent validation samples sets. Correlation with R-squared of similar to 0.99 was found between the calculated and reference concentrations, which indicates that LIBS is a promising technique for the in situ rapid determination of the major elements present in solid and slurry phosphate samples.