Evaluation of grinding methods for pellets preparation aiming at the analysis of plant materials by laser induced breakdown spectrometry

Author(s)

Gomes, Marcos da Silva ^{[1, 2]} ; Santos Junior, Dario ^[3] ; Nunes, Lidiane Cristina ^[2] ; Arantes de Carvalho, Gabriel Gustinelli ^[2] ; Leme, Flavio de Oliveira ^[2] ; Krug, Francisco Jose ^[2]

Affiliation

^[1] Univ Fed Sao Carlos, Dept Quim, BR-13560 Sao Carlos, SP - Brazil

^[2] Univ Sao Paulo, CENA, Lab Quim Analit, BR-13416000 Piracicaba, SP - Brazil

^[3] Univ Fed Sao Paulo, Dept Ciencias Exatas & Terra, Diadema, SP - Brazil

• Document type: Journal article
• Source: Talanta; v. 85, n. 4, p. 1744-1750, SEP 30 2011.
• Web of Science Citations: 23

Abstract

It has been demonstrated that laser induced breakdown spectrometry (LIBS) can be used as an alternative method for the determination of macro (P, K. Ca, Mg) and micronutrients (B, Fe, Cu, Mn, Zn) in pellets of plant materials. However, information is required regarding the sample preparation for plant analysis by LIBS. In this work, methods involving cryogenic grinding and planetary ball milling were evaluated for leaves comminution before pellets preparation. The particle sizes were associated to chemical sample properties such as fiber and cellulose contents, as well as to pellets porosity and density. The pellets were ablated at 30 different sites by applying 25 laser pulses per site (Nd:YAG@1064 nm, 5 ns, 10 Hz, 25J cm(-2)). The plasma emission collected by lenses was directed through an optical fiber towards a high resolution echelle spectrometer equipped with an ICCD. Delay time and integration time gate were fixed at 2.0 and 4.5 mu s, respectively. Experiments carried out with pellets of sugarcane, orange tree and soy leaves showed a significant effect of the plant species for choosing the most appropriate grinding conditions. By using ball milling with agate materials, 20 min grinding for orange tree and soy, and 60 min for sugarcane leaves led to particle size distributions generally lower than 75 mu m. Cryogenic grinding yielded similar particle size distributions after 10 min for orange tree, 20 min for soy and 30 min for sugarcane leaves. There was up to 50% emission signal enhancement on LIBS measurements for most elements by improving particle size distribution and consequently the pellet porosity. (C) 2011 Elsevier B.V. All rights reserved. (AU)

• 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
• 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: 04/15965-2 - Implementation and development of Laser Induced Breakdown Spectroscopy (LIBS)
• Grantee: Francisco José Krug
• Support Opportunities: Research Projects - Thematic Grants