Accuracy enhancement of a multivariate calibration for lead determination in soils by laser induced breakdown spectroscopy

We have investigated matrix effects and spectral interferences on example of lead determination in different types of soils by laser induced breakdown spectroscopy (LIBS). Comparison between analytical performances of univariate and multivariate calibrations with the use of different laser wavelengt...

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Bibliographic Details
Published in:Spectrochimica acta. Part B: Atomic spectroscopy 2018-02, Vol.140, p.65-72
Main Authors: Zaytsev, Sergey M., Krylov, Ivan N., Popov, Andrey M., Zorov, Nikita B., Labutin, Timur A.
Format: Article
Language:English
Subjects:
Ablation
Accuracy
Analytical methods
Calibration
Comparative analysis
Components
DNA
Educational institutions
Iron
Laser induced breakdown spectroscopy
Lasers
Lead
Magnesium
Manganese
Modelling
Neodymium lasers
Niobium
Nucleotide sequence
PCR
Semiconductor lasers
Soil
Soil investigations
Soil types
Spectra
Spectroscopy
Spectrum analysis
Wavelength
YAG lasers
Zirconium
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Summary:We have investigated matrix effects and spectral interferences on example of lead determination in different types of soils by laser induced breakdown spectroscopy (LIBS). Comparison between analytical performances of univariate and multivariate calibrations with the use of different laser wavelength for ablation (532, 355 and 266nm) have been reported. A set of 17 soil samples (Ca-rich, Fe-rich, lean soils etc., 8.5–280ppm of Pb) was involved into construction of the calibration models. Spectral interferences from main components (Ca, Fe, Ti, Mg) and trace components (Mn, Nb, Zr) were estimated by spectra modeling, and they were a reason for significant differences between the univariate calibration models obtained for a three different soil types (black, red, gray) separately. Implementation of 3rd harmonic of Nd:YAG laser in combination with multivariate calibration model based on PCR with 3 principal components provided the best analytical results: the RMSEC has been lowered down to 8ppm. The sufficient improvement of the relative uncertainty (up to 5–10%) in comparison with univariate calibration was observed at the Pb concentration level>50ppm, while the problem of accuracy still remains for some samples with Pb concentration at the ~20ppm level. We have also discussed a few possible ways to estimate LOD without a blank sample. The most rigorous criterion has resulted in LOD of Pb in soils being ~13ppm. Finally, a good agreement between the values of lead content predicted by LIBS (46±5ppm) and XRF (42.1±3.3ppm) in the unknown soil sample from Lomonosov Moscow State University area was demonstrated. [Display omitted] •Combination of LIBS and multivariate calibration for accurate analysis of low lead content in soil•Laser harmonics selection for robust calibration model•Study of different soil types
ISSN:0584-8547
1873-3565
DOI:10.1016/j.sab.2017.12.005