Optimization and validation of a LIBS method for the determination of macro and micronutrients in sugar cane leaves

Author(s)

Nunes, Lidiane Cristina ^{[1, 2]} ; Braga, Jez Willian Batista ^[3] ; Trevizan, Lilian Cristina ^[2] ; de Souza, Paulino Florencio ^[2] ; Arantes de Carvalho, Gabriel Gustinelli ^[2] ; Santos Junior, Dario ^[4] ; Poppi, Ronei Jesus ^[5] ; Krug, Francisco Jose ^[2]

Affiliation

^[1] Univ Fed Sao Carlos, Dept Quim, BR-13565905 Sao Carlos, SP - Brazil

^[2] Univ Sao Paulo, Ctr Energia Nucl Agr, BR-13416000 Piracicaba, SP - Brazil

^[3] Univ Brasilia, Inst Quim, BR-70904970 Brasilia, DF - Brazil

^[4] Univ Fed Sao Paulo UNIFESP, BR-09972270 Diadema, SP - Brazil

^[5] Univ Estadual Campinas, Inst Quim, BR-13084971 Campinas, SP - Brazil

• Document type: Journal article
• Source: Journal of Analytical Atomic Spectrometry; v. 25, n. 9, p. 1453-1460, 2010.
• Web of Science Citations: 52

Abstract

Laser induced breakdown spectrometry (LIBS) was applied for the determination of macro (P, K, Ca, Mg) and micronutrients (B, Cu, Fe, Mn and Zn) in sugar cane leaves, which is one of the most economically important crops in Brazil. Operational conditions were previously optimized by a neuro-genetic approach, by using a laser Nd:YAG at 1064 nm with 110 mJ per pulse focused on a pellet surface prepared with ground plant samples. Emission intensities were measured after 2.0 mu s delay time, with 4.5 mu s integration time gate and 25 accumulated laser pulses. Measurements of LIBS spectra were based on triplicate and each replicate consisted of an average of ten spectra collected in different sites (craters) of the pellet. Quantitative determinations were carried out by using univariate calibration and chemometric methods, such as PLSR and iPLS. The calibration models were obtained by using 26 laboratory samples and the validation was carried out by using 15 test samples. For comparative purpose, these samples were also microwave-assisted digested and further analyzed by ICP OES. In general, most results obtained by LIBS did not differ significantly from ICP OES data by applying a t-test at 95% confidence level. Both LIBS multivariate and univariate calibration methods produced similar results, except for Fe where better results were achieved by the multivariate approach. Repeatability precision varied from 0.7 to 15% and 1.3 to 20% from measurements obtained by multivariate and univariate calibration, respectively. It is demonstrated that LIBS is a powerful tool for analysis of pellets of plant materials for determination of macro and micronutrients by choosing calibration and validation samples with similar matrix composition. (AU)

• 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