微乳液进样-石墨炉原子吸收光谱法测定芝麻油中铅

Determination of Lead in Sesame Oil by GFAAS with Microemulsion Sampling

芝麻油作为一种可直接食用的佐餐植物油,铅等重金属的含量检测具有重要意义。建立了微乳液直接进样-石墨炉原子吸收光谱法测定芝麻油中痕量铅的方法。以复合表面活性剂洗洁精为乳化剂,正丁醇为助乳化剂,制备了稳定性较好的芝麻油微乳液。优化了石墨炉原子吸收光谱法微乳液中铅测定条件,磷酸二氢铵和硝酸镁混合溶液为基体改进剂,灰化温度800℃,原子化温度1800℃条件下,测定芝麻油中铅的浓度为33.6 ng.g-1,精密度为2.79%,检出限为4.1 ng·mL-1,加标平均回收率为100.5%,相对标准偏差为2.46%。该法用于实际油样的测定,不需进行复杂的样品前处理,方法快速准确,结果令人满意。

Problems of lead contamination in edible oil are emphasized increasingly at present. Sesame oil can be directly edible as an appetizer, and determination of lead in it will be helpful for quality control of sesame oil. An effective method was developed for the rapid determination of lead in sesame oil by graphite furnace atomic absorption spectrometry （GFAAS） with microemulsion sampling. In this paper, a clear microemulsion of sesame oil was obtained, by using a detergent as emulsifier and n - butyl alcohol as auxiliary emulsifying agent. It was found that the optimal determination conditions of lead by GFAAS with mieroemulsion as follows： a mixture solution of NH4H2PO4 and Mg（ NO3 ）2 as matrix modifier, ashing temperature of 900℃ and atomization temperature of 1900℃. Under the conditions, the determined content of lead in sesame oil was 33.6ng/mL with a relative standard deviation of 2.79%, and the detection limit of the method was 4. 1ng./mL. The average recovery rate for lead was 100.5% with a relative standard deviation of 2.46%. Therefore, this method is rapid, accurate and applicable without cumbersome pretreatment of samples.