Determination of Cd, Cr and Pb in phosphate fertilizers by laser-induced breakdown spectroscopy

Author(s)

Nunes, Lidiane Cristina ^[1] ; Arantes de Carvalho, Gabriel Gustinelli ^[1] ; Santos Junior, Dario ^[2] ; Krug, Francisco Jose ^[1]

Affiliation

^[1] Univ Sao Paulo, NAPTISA Res Support Ctr Technol & Innovat Sustain, Ctr Nucl Energy Agr, BR-13416000 Piracicaba, SP - Brazil

^[2] Univ Fed Sao Paulo, BR-09972270 Diadema, SP - Brazil

• Document type: Journal article
• Source: SPECTROCHIMICA ACTA PART B-ATOMIC SPECTROSCOPY; v. 97, p. 42-48, JUL 1 2014.
• Web of Science Citations: 25

Abstract

A validated method for quantitative determination of Cd, Cr, and Pb in phosphate fertilizers by laser-induced breakdown spectroscopy (LIBS) is presented. Laboratory samples were comminuted and homogenized by cryogenic or planetary ball milling, pressed into pellets and analyzed by LIBS. The experimental setup was designed by using a Q-switched Nd:YAG at 1064 nm with 10 Hz repetition rate, and the intensity signals from Cd II 214.441 nm, Cr II 267.716 nm and Pb II 220.353 nm emission lines were measured by using a spectrometer furnished with an intensified charge-coupled device. LIBS parameters (laser fluence, lens-to-sample distance, delay time, integration time gate, number of sites and number of laser pulses per site) were chosen after univariate experiments with a pellet of NIST SRM 695 (Trace Elements in Multi-Nutrient Fertilizer). Calibration and validation were carried out with 30 fertilizer samples from single superphosphate, triple superphosphate, monoammonium phosphate, and NPK mixtures. Good results were obtained by using 30 pulses of 50 J cm(-2) (750 mu m spot size), 2.0 mu s delay time and 5.0 mu s integration time gate. No significant differences between Cd, Cr, and Pb mass fractions determined by the proposed LIBS method and by ICP OES after microwave-assisted acid digestion (AOAC 2006.03 Official Method) were found at 95% confidence level. The limits of detection of 1 mg kg(-1) Cd, 2 mg kg(-1) Cr and 15 mg kg(-1) Pb and the precision (coefficients of variation of results ranging from 2% to 15%) indicate that the proposed LIES method can be recommended for the determination of these analytes in phosphate fertilizers. (C) 2014 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