微波消解-原子吸收光谱法测定地沟油中5种微量元素

目的:探讨地沟油与食用油中5种微量元素之间的差别。方法:选取不同种类的食用油5份和自制猪油1份(均称食用油),收集地沟油和煎炸老油各3份,准确称取各样品0.3~0.4 g,采用微波消解法制成可供测定的溶液,用原子吸收光谱法测定铜(Cu)、锌(Zn)、锰(Mn)、铅(Pb)和铁(Fe)的含量。结果:在实验选定浓度范围内,5种微量元素回收率为97.6%~102.4%,相对标准偏差为0.6%~2.5%。煎炸老油中5种微量元素的含量和大豆油相近;6种食用油中Cu、Zn、Mn和Pb的含量与地沟油差别不大;地沟油和煎炸老油中Fe的含量比6种食用油高(P<0.01)。结论:地沟油中Cu、Zn、Mn、Pb元素含量与食用油的含量差别不大,而Fe元素含量增高,可能因地沟油在炼制、运输过程中与铁制品长期接触有关。

Determination of five kinds of trace elements in hogwash oil by microwave digestion-atomic absorption spectrometry

Objective:To explore the differences of five kinds of trace elements between edible cooking oil and hogwash oil. Methods:Different kinds of 5 parts edible oil and 1 part homemade lard oil,3 parts old cooking oil and 3 parts hogwash oil were collected. In each sample,0. 3 ~ 0. 4 g was weighed accurately. The samples were digested into a solution for determination by microwave. The contents of copper( Cu) ,zinc( Zn) ,manganese( Mn) ,lead( Pb) and iron( Fe) were determined by atomic absorption spectrometry. Results:In the experimental concentration range,the recovery rate was between 97. 6% to 102. 4%,the relative average deviation was 0. 6% to 2. 5%. The contents of 5 kinds of trace elements in old cooking oil were similar to soybean oil,and there had no differences of Cu,Zn,Mn and Pb contents between the edible oil and hogwash oil,whereas Fe content in old cooking oil and hogwash oil was higher than that in the edible oil(P<0. 01). Conclusions:There had no statistical differences of elements Cu,Zn,Mn and Pb contents between the edible oil and hogwash oil. Fe content was increased in hogwash oil,which may be due to the long-term exposure to the iron products when the hogwash oil was refined and transported.