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Direct determination of nickel in petroleum by solid sampling–graphite furnace atomic absorption spectrometry

Brandão, Geisamanda Pedrini, de Campos, Reinaldo Calixto, de Castro, Eustáquio Vinicius Ribeiro, de Jesus, Honério Coutinho
Analytical and bioanalytical chemistry 2006 v.386 no.7-8 pp. 2249-2253
atomic absorption spectrometry, detection limit, nickel, oils, palladium, petroleum, temperature
A procedure for the direct GFAAS determination of Ni in petroleum samples using a solid sampling strategy is proposed. Palladium was used as conventional modifier. Central composite design multivariate optimization defined the optimum temperature program and the Pd mass, allowing calibration using aqueous analytical solution. The limit of detection (LOD) at the optimized conditions was 0.23 ng of Ni, for typical sample masses between of 0.10 and 0.60 mg. Linearity at least up to 11 ng of Ni and a characteristic mass of 45 pg were observed, defining a dynamic range between 0.52 and 110 μg g⁻¹. Typical coefficients of variation (n = 10) in the analysis of oil reference materials were 7%. Method validation was performed both by the analysis of oil certified reference materials and by comparison with an independent method (ASTM 5863-B). No statistically significant difference was observed between obtained and expected values. The total determination cycle lasted 5 min, equivalent to a sample throughput of 6 h⁻¹ for duplicate determinations.