原子吸收光谱法测定砖茶和花茶中锌和铁的含量
摘要：为了解青砖茶和茉莉花茶中锌和铁元素的含量及其茶水中元素含量的变化，本研究采用微波消解方法处理茶叶，用火焰原子吸收光谱法测定茶叶中锌和铁的含量，同时对两种茶水中锌和铁的含量随时间的变化也进行了一番研究探讨。结果表明，同种元素在不同种茶叶中含量有一定差别，青砖茶中锌含量为120.93mg/kg，铁含量为849.50mg/kg，茉莉花茶中锌含量为66.13mg/kg，铁含量为236.33mg/kg。本实验方法锌的回收率为87.00%~116.83%，铁的回收率为95.13%~118.17%，回收率范围在80%~120%之间，相对标准偏差不超过5.1031%,该方法准确度良好。砖茶中锌、铁离子最大溶出率分别为14.39%、2.49%，花茶中锌、铁离子最大溶出率分别为 40.83%、8.96%，说明不同种元素在同种茶叶中的溶出率并不相同，锌离子溶出率大于铁离子的溶出率。
关键词：火焰原子吸收光谱法，微波消解法，茶叶，锌，铁，溶出率
Determination of Zn and Fe in brick tea and scented tea by atomic absorption spectrometry
Abstract：The study aimed to understand the content of zinc and iron in brick tea and jasmine tea and the elements change in tea. Brick tea and jasmine tea were digested by microwave digestion method, zinc and iron content in tea were determined by flame atomic absorption spectrometry. At the same time, zinc and iron content changes along with the time change in two tea were discussed. The results showed that the same element in different kinds of tea had a certain difference in the content, and the content of zinc in brick tea was 120.93 mg/kg, the content of iron in brick tea was 849.50 mg/kg, the content of zinc in jasmine tea was 66.13 mg/kg, the content of iron in jasmine tea was 236.33 mg/kg. The experiment method of zinc recovery rate was 87.00% ~ 116.83%, the recovery rate of iron was 95.13% ~ 118.17%, recovery rate ranged between 80% ~ 120%, relative standard deviation was less than 5.1031%, that showed the method had good accuracy. Zinc and iron ion in brick tea biggest dissolution rate were 14.39% and 2.49%, zinc and iron ion in tea biggest dissolution rate were 40.83% and 8.96%, which explained that different kinds of elements in the same tea dissolution rate was not the same, and zinc ion dissolution rate was greater than the dissolution rate of iron ion.
Key Words: Flame atomic absorption spectrometry, Microwave digestion, Tea, Zinc, Iron, Dissolution rate
目 录
文献综述………………………………………………………………………………1
1前言………………………………………………………………………………….3
2材料与方法………………………………………………………………………….4
2.1实验仪器..…………………………………………………………………….4
2.2实验试剂..……………………………………………………………………4
2.3仪器工作条件…………………………………………………………………4
2.4实验方法 ……………………………………………………………………4
2.4.1样品前处理 ……………………………………………………………….4
2.4.2标准储备溶液的配制 …………………………………………………….4
2.4.3方法检出限实验 …………………………………………………………..5
2.4.4标准曲线的绘制……………………………………………………………5
2.4.5精密度实验…………………………………………………………………5
2.4.6样品中元素总含量的测定…………………………………………………6
2.4.7样品加标回收率的测定……………………………………………………6
2.4.8不同时间茶水中元素溶出率的测定…………………………………… ..6
3实验结果…………………………………………………………………………….7
3.1检出限 ……………………………………………………………………….7
3.2标准曲线的绘制 …………………………………………………………….8
3.3精密度 ………………………………………………………………………9
3.4样品元素总含量..…………………………………………………………….9
3.5加标回收率.…………………………………………………………………10
3.6溶出率.………………………………………………………………………12
4讨论………………………………………………………………………………….14
4.1前处理方法………………………………………………………………….14
4.2食品健康与安全…………………………………………………………….15
5小结…………………………………………………….……………………………16
参考文献………………………..……………………………………………………17
致谢…………….…………………………….……………………………………….18
