Quantitative Analysis of Fe Content in Iron Ore via External Calibration in Conjunction with Internal Standardization Method Coupled with LIBS

The external calibration in conjunction with internal standardization(ECIS) coupled with laser-induced breakdown spectroscopic(LIBS) technique was proposed to perform the quantitative analysis of Fe content in iron ore. The plasma temperature and the electron number density were calculated to prove that the plasma was under local thermodynamic equilibrium(LTE) conditions and to ensure that the integral intensities of Fe I lines were reasonable. In addition, the result of the quantitative analysis shows a content of (20.26 +/- 0.59)% by mass of Fe in the iron ore. It was determined by four calibration curves, drawn for four emission lines of Fe 1(373.48, 373.71, 404.58 and 438.35 nm) normalized by Mn I line, base on the ECIS method which can eliminate the influence of matrix effect and improve the accuracy of quantitative analysis, compared with the standard addition method. Both the results of these two analytical methods were compared with that listed in the Standard Substance Certificate. The percentage content of Fe in the same sample of iron ore by the ECIS method was (20.17 +/- 0.08)% by mass, which shows a good performance to analyze the Fe content of iron ore in combination with LIBS.