ABSTRACT
Bio-diesel oil has attracted much attention as a substitutable energy sources for its renewable and eco-friendly property. However, problems of lead contamination in fuel are also emphasized increasingly at present. So it was of quite significance to determine the contents of lead in bio-diesel oil and its raw material rapeseed oil. An effective method was developed for the rapid determination of lead in rapeseed oil and bio-diesel oil by graphite furnace atomic absorption spectrometry (GFAAS) after their stabilization as microemulsions. In this research work, polyethyleneglycol octyl phenyl ether and n-butanol were used for emulsifier and auxiliary emulsifying agent, respectively. For Pb, efficient thermal stabilization was obtained using NH4H2PO4 as matrix modifier. Sample stabilization was necessary because of evident analyte losses that occurred immediately after sampling. Excellent long-term sample stabilization and the influence of the microemulsion composition on the GFAAS response were observed by mixing different organic solvents. The ashing and atomization temperature and ramp rate influenced the sensitivity obtained for Ph. Take this into account, the optimum conditions of the graphite furnace atomic absorption spectrometric determination of Pb in rapeseed oil and bio-diesel oil samples were investigated. The results showed that the microemulsion was quite stable when the value of V(20% polyethyleneglycol octyl phenyl ether), V(n-butanol), V(oil) and V(water) was 0.1: 8.9: 0.5: 0.5, without matrix interference effect. The determination limit of the proposed method was 126.2 microg x L(-1) for Pb, comfortably below the values found in the analyzed samples. The recoveries were from 81.8% to 109.0%, which performed using the addition of different concentrations of lead to bio-diesel oil, rapeseed oil and petrochemical diesel samples. The relative standard deviation of determination was 5.84%. This work showed the great efficiency of the microemulsion, indicating that it is possible to extract lead from the oil phase. The method was applied to the determination of lead in oil samples with satisfactory results.
