微乳液进样-石墨炉原子吸收光谱法测定生物柴油及其原料菜籽油中铅含量

Determination of Lead in Microemulsified Rapeseed Oil and Bio-Diesel Oil by GFAAS

生物柴油作为一种替代能源,以其良好的可再生性和环境友好性受到世界各国的关注,同时燃料中铅污染也日益引起人们的重视,因此测定生物柴油及其原料菜籽油中铅的含量具有重要的意义。建立了微乳液进样-石墨炉原子吸收法测定油样中铅含量的新方法。以聚乙二醇辛基苯基醚为乳化剂,正丁醇为助乳化剂,NH4H2PO4为基体改进剂,研究了微乳液的稳定性和微乳化剂配比对测定结果的影响,优化了石墨炉原子吸收光谱法测定条件。研究表明,当20%聚乙二醇辛基苯基醚∶正丁醇∶油样∶水相=0.1∶8.9∶0.5∶0.5(φ)时,体系能形成稳定的微乳液。本方法的检出限为126.2μg·L-1,样品平均回收率在81.8%～109.0%之间,相对标准偏差为5.84%。该法用于实际油样的测定,结果令人满意。

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 NH4H2 PO4 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 mieroemulsion 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 Pb. 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 sta ble 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 μg · 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.