Simultaneous determination of Cr, Fe, Ni and V in crude oil by emulsion sampling graphite furnace atomic absorption spectrometry

[摘要] In this work a simple and reliable method for the simultaneous determination of Cr, Fe, Ni and V in crude oil, using emulsion sampling graphite furnace atomic absorption spectrometry is proposed. Under the best conditions, sample masses around 50 mg were weighed in polypropylene tubes and emulsified in a mixture of 0.5% (v v−1) hexane + 6% (m v−1) Triton X-100®. Considering the compromised conditions, the pyrolysis an atomization temperatures for the simultaneous determination of Cr, Fe, Ni and V were 1400 °C and 2500 °C, respectively. Aliquots of 20 μL of reference solution and sample emulsion were co-injected into the graphite tube with 10 μL of 1.0 g L−1Mg(NO3)2 as chemical modifier. The detection limits (n = 10, 3σ) and characteristic masses were, respectively: 0.07 μg g−1 and 19 pg for Cr; 2.15 μg g−1 and 31 pg for Fe; 1.25 μg g−1 and 44 pg for Ni; and 1.15 μg g−1 and 149 pg for V. The reliability of the proposed method was checked by fuel oil Standard Reference Material (SRMTriton X-100®1634c – NIST) analysis. The concentrations found presented no statistical differences compared to the certified values at 95% confidence level...

[学科分类] 分析化学