Vieira, Alan Lima [UNESP]Silva, Tiago Varão [UNESP]de Sousa, Felipe Schiavon InocêncioSenesi, Giorgio SaverioJúnior, Dário SantosFerreira, Edilene Cristina [UNESP]Neto, José Anchieta Gomes [UNESP]2018-12-112018-12-112018-06-01Microchemical Journal, v. 139, p. 322-326.0026-265Xhttp://hdl.handle.net/11449/179652A 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 (I) 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)2CO 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 ≥0.993, RSD ≤8% and LOQ 5.3% (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.322-326engFertilizer analysisLIBSPhosphorus determinationSpark dischargeArtigo10.1016/j.microc.2018.03.011Acesso aberto2-s2.0-850434517702-s2.0-85043451770.pdf