Determinations of phosphorus in fertilizers by spark discharge-assisted laser-induced breakdown spectroscopy

Autor(es)

Vieira, Alan Lima ^[1] ; Silva, Tiago Varao ^[1] ; Inocencio de Sousa, Felipe Schiavon ^[2] ; Senesi, Giorgio Saverio ^[3] ; Santos Junior, Dario ^[4] ; Ferreira, Edilene Cristina ^[1] ; Gomes Neto, Jose Anchieta ^[1]

Afiliação do(s) autor(es)

^[1] Sao Paulo State Univ UNESP, Analyt Chem Dept, POB 355, BR-14801970 Araraquara, SP - Brazil

^[2] Univ Sao Paulo, Dept Elect & Comp Engn, BR-13566590 Sao Carlos, SP - Brazil

^[3] CNR, Ist Nanotecnol NANOTEC, PLasMI Lab, Via Amendola 122-D, I-70126 Bari - Italy

^[4] Fed Univ Sao Paulo UNIFESP, Exact & Earth Sci Dept, BR-09913030 Diadema, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Microchemical Journal; v. 139, p. 322-326, JUN 2018.
• Citações Web of Science: 7

Resumo

A spark discharge system was coupled to laser-induced breakdown spectroscopy (SD-LIBS) to improve sensitivity in the determination of P in fertilizers. A LIBS system consisting of a Q-switched Nd:YAG laser operating at 1064 nm and emitting pulses at 50 mJ with a fluence of 70 J cm(-2) at the focal point was used. Results of preliminary experiments suggested that the most appropriate wavelength to measure P was the P (1) line at 214.9 nm, which did not show interferences by Fe, Cu and Zn. The electrical discharge was provided by a homemade high-voltage electronic circuit consisting of two cylindrical tungsten electrodes at the optimized output voltage of 4.5 kV, with tips arranged at the optimal distances of 4 mm between them and 2 mm above the sample surface. To minimize the expected matrix effects calibration standards of P2O5 in the range of 4.8 and 33.3% were prepared by mixing various amounts of a phosphate rock reference material (SRM-120c) with a mixture of CaCO3, CaSO4, (NH2)(2)CO and KCl at a 1:1:1:1 mass ratio. The calibration curves obtained at a 4.5 kV SD-LIBS output voltage showed correlation coefficients RSD <= 8% and LOQ5.3% (m/m) P2O5. Data obtained by analyzing commercial samples by the proposed system were in good agreement, at 95% confidence level, with those obtained by using high-resolution continuum-source flame atomic absorption spectroscopy. (C) 2018 Elsevier B.V. All rights reserved. (AU)

• Processo FAPESP: 04/14212-0 - Desenvolvimento de métodos analíticos envolvendo determinações multielementares em produtos agroindustriais e petroquímicos por espectrometria de absorção atômica em chama com fonte contínua
• Beneficiário: José Anchieta Gomes Neto
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 15/24757-9 - Avaliação da técnica LIBS para determinação de Ca, K, P e N em novos fertilizantes inteligentes e sustentáveis
• Beneficiário: Edilene Cristina Ferreira
• Modalidade de apoio: Auxílio à Pesquisa - Regular