Influence of particle size distribution on the analysis of pellets of plant materials by laser-induced breakdown spectroscopy

Author(s)

Arantes de Carvalho, Gabriel Gustinelli ; Santos, Dario, Jr. ; Gomes, Marcos da Silva ; Nunes, Lidiane Cristina ; Bueno Guerra, Marcelo Braga ; Krug, Francisco Jose

• Document type: Journal article
• Source: SPECTROCHIMICA ACTA PART B-ATOMIC SPECTROSCOPY; v. 105, p. 6-pg., 2015-03-01.

Abstract

Pellets of sieved plant materials (150, 106, 75,53 and 20 pm sieve apertures) were prepared and analyzed by laser-induced breakdown spectroscopy (LIBS), and the results for Ca, K, Mg, P, B and Mn were discussed as a function of particle size distribution. This parameter is of key importance for appropriate test sample presentation in the form of pressed pellets for quantitative analysis by LIBS. Experiments were carried out with a Q-switched Nd:YAG laser at 1064 nm, and a spectrometer with Echelle optics and an intensified charge-coupled device. Results indicated that smaller particles yielded up to 50% emission signal intensities' enhancement and attained better measurements' precision (site-to-site variation). Moreover, matrix effects were reduced by analyzing pellets prepared from <75 mu m sieved fractions (mean particle size = 32 mu m; d(95) = 102 mu m) and by using a 50 J cm(-2) laser fluence (220 mJ per pulse; 750 mu m laser spot size). The preparation of pellets from laboratory samples with monomodal particle size distributions, where most particles were smaller than 100 mu m, was decisive for improving analyte micro-homogeneity within the test samples and for attaining lower coefficients of variation of measurements, typically lower than 10% (n = 10 sites per pellet; 20 laser pulses per site). (C) 2014 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 10/17158-8 - Evaluation of laser induced breakdown spectrometry (LIBS) for determination of inorganic contaminants in agricultural fertilizers
• Grantee: Lidiane Cristina Nunes
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 12/16203-5 - Strategies for the direct analysis of sugar cane leaves by laser induced breakdown spectroscopy(LIBS)
• Grantee: Marcelo Braga Bueno Guerra
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 10/16379-0 - Sampling strategies for analysis of biological materials by laser induced breakdown spectrometry
• Grantee: Gabriel Gustinelli Arantes de Carvalho
• Support Opportunities: Scholarships in Brazil - Doctorate