Využití spektrometrie laserem indukovaneho mikroplazmatu pro kvalitativní a kvantitativní analýzu hornin

Laser-Induced Breakdown Spectroscopy for in-situ Qualitative and Quantitative Analysis of Mineral Ores

journal article in Web of Science

en

In this work, the potential of Laser-Induced Breakdown Spectroscopy (LIBS) for discrimination and analysis of geological materials was examined. The research was focused on classification of mineral ores using their LIBS spectra prior to quantitative determination of copper. Quantitative analysis is not a trivial task in LIBS measurement because intensities of emission lines in laser-induced plasmas (LIP) are strongly affected by the mineral matrix (matrix effect). To circumvent this effect, typically matrix matched standards are used to obtain matrix dependent calibration curves. If the sample set consists of a mixture of different matrices, even in this approach, the corresponding matrix has to be known prior to the downstream data analysis. For this categorization, the multielemental character of LIBS spectra can be of help. In this contribution, a principal component analysis (PCA) was employed on the measured data set to discriminate individual rocks as individual matrices against each other according to their overall elemental composition. 27 igneous rock samples were analyzed in the form of fine dust, classified and subsequently quantitatively analyzed. Two different LIBS setups in two laboratories were used to prove the reproducibility of classification and quantification. A superposition of partial calibration plots constructed from the individual clustered data displayed a large improvement in precision and accuracy compared to the calibration plot constructed from all ore samples. The classification of mineral samples with complex matrices can thus be recommended prior to calibration analysis.

Výsledky uvedené v této disertacní práci potvrzují vhodnost použití metody LIBS v težebním prumyslu. Primárním cílem bylo stanovit množství medi v ruzných druzích vyvrelých hornin. Bylo zjišteno, že matricní jev muže výrazne ovlivnit merení metodou LIBS, prestože byly namereny pouze malé soubory vzorky stejné horniny. Proto je doporuceno roztrídit vzorky s ohledem na podobnosti ve složení matric, respektive pomery množství matricních prvku. Následne je možné urcit množství analytu ve vzorku s vetší presností.

In this work, the potential of Laser-Induced Breakdown Spectroscopy (LIBS) for discrimination and analysis of geological materials was examined. The research was focused on classification of mineral ores using their LIBS spectra prior to quantitative determination of copper. Quantitative analysis is not a trivial task in LIBS measurement because intensities of emission lines in laser-induced plasmas (LIP) are strongly affected by the mineral matrix (matrix effect). To circumvent this effect, typically matrix matched standards are used to obtain matrix dependent calibration curves. If the sample set consists of a mixture of different matrices, even in this approach, the corresponding matrix has to be known prior to the downstream data analysis. For this categorization, the multielemental character of LIBS spectra can be of help. In this contribution, a principal component analysis (PCA) was employed on the measured data set to discriminate individual rocks as individual matrices against each other according to their overall elemental composition. 27 igneous rock samples were analyzed in the form of fine dust, classified and subsequently quantitatively analyzed. Two different LIBS setups in two laboratories were used to prove the reproducibility of classification and quantification. A superposition of partial calibration plots constructed from the individual clustered data displayed a large improvement in precision and accuracy compared to the calibration plot constructed from all ore samples. The classification of mineral samples with complex matrices can thus be recommended prior to calibration analysis.

spektrometrie laserem indukovaneho mikroplazmatu, LIBS, geologické vzorky, matricní efekt

Laser-induced breakdown spectroscopy; LIBS; Chemometrics; Principal Component Analysis; geochemical analysis

2014

01.11.2014

0584-8547

101

11

155–163

9