电感耦合等离子体质谱(ICP-MS)法研究发芽对糙米重金属元素(镉、铅、砷)含量影响

Using ICP-MS to study the effect of germination on the content of heavy metal(Cd,Pb,As) in brown rice

重金属含量超标是我国稻米生产面临严重食品安全隐患之一。糙米中重金属主要以蛋白、纤维、植酸结合态存在，在糙米发芽过程中，蛋白、纤维素、植酸在蛋白酶、纤维素酶、植酸酶作用下部分降解；由此，结合态重金属可能转变为游离态，从糙米内部迁移而出，从而可降低米中重金属含量。基于此，以市场收集8种糙米为样品，采用微波消解、ICP—MS法测定这些糙米发芽前后重金属镉、铅、砷含量，为糙米、发芽糙米产品安全食用提供参考。结果表明，8个样品中，3个样品镉超标，5个样品铅、砷含量超标，镉、铅、砷最高超标幅度分别达589．5％、641％、2625％；对重金属（镉、铅、砷）超标糙米样品而言，经发芽后，糙米铅、砷、镉含量降低幅度分别为89．0％～100％、60％～100％、6．2％～35．5％；所以，糙米经发芽后能有效降低米中铅和砷含量，但对降低镉含量效果稍差。

Heavy metal content exceed the standard is a hidden hazard of our country＇s rice production. In brown rice, the heavy metal ions are mainly combined with the proteins, fibril, and phytic acid, which would be partly hydrolyzed by proteases, cellulose and phytase during the germination process of brown rice, thus, the combined state of the heavy metals may change into free states, and then emigrate from the internal of brown rice, resulting in reduce the heavy metal content of brown rice. Based on this consideration, this article collected 8 kinds of brown rice from the market as the sample, the microwave digestion, ICP-MS method was used to determine the content of heavy metal cadmium, lead, arsenic in the brown rice and germinated brown rice. The results showed that： among the 8 samples, 3 samples＇ cadmium content exceed the standard, 5 samples＇ lead, arsenic content exceed the standard, the highest content of cadmium, lead, arsenic exceed the standard 589.5%, 641% ,2625%, respectively; some samples also exist at the same time a variety of heavy metal exceed the standard of heavy metals （cadmium, lead, arsenic） exceed the standard of brown rice samples, germination reduce content of lead, arsenic, cadmium in brown rice for 89.0%- 100%, 60%- 100%, 6.2%-35.5%, respectively. In conclusion, germination can effectively reduce the content of lead and arsenic, but with less effectiveness to reduce the cadmium content.