Fast emulsion-based method for simultaneous determination of Co, Cu, Pb and Se in crude oil, gasoline and diesel by graphite furnace atomic absorption spectrometry

摘要

A method for the simultaneous determination of Co, Cu, Pb and Se in crude oil, gasoline and diesel samples using emulsion-based sampling and GF AAS is proposed. 400 mg of sample was weighted in volumetric flask following the sequential addition of 125 μL of hexane and 7.5 mL of Triton X-100 ~? (20% m v-1). Subsequently, the mixture was stirred in ultrasonic bath, during 30 min, before dilution to 25 mL with deionized water. Aliquots of 20 μL of reference solution or sample emulsion were co-injected into the graphite tube with 10 μL of 2 g L~(-1) Pd(NO_3)_2. The pyrolysis and atomization temperatures were 1300 C and 2250 C, respectively. The limits of detection (n=10, 3σ) and characteristic masses were 0.02 μg g~(-1) (0.32 μg L~(-1)) and 18 pg for Co, 0.03 μg g~(-1) (0.48 μg L~(-1)) and 15 pg for Cu, 0.04 μg g~(-1) (0.64 μg L~(-1)) and 48 pg for Pb, and 0.11 μg g~(-1) (1.76 μg L~(-1)) and 47 pg for Se. The reliabilities of the proposed method for Co and Se were checked by SRM ? 1634c Residual Oil analysis. The found values are in accordance to the SRM at 95% confidence level (Student's t-test). Each sample was spiked with 0.18 μg g~(-1) of Co, Cu, Pb and Se and the recoveries varied from 92% to 116% for Co, 83% to 117% for Cu, 72% to 117% for Pb, and 82% to 122% for Se.