石墨管性能变化对无公害水果蔬菜中铅测定的影响

Effect of Graphite Tube Functional Change on Determination of the Lead in Non-polluted Fruits and Vegetables

用石墨炉原子吸收光谱法和扫描电镜观测法分析了不同测定次数的石墨管原子吸收信号、相关技术指标及表面结构变化情况,探讨石墨管性能变化对无公害水果蔬菜中铅测定的影响程度及其发生规律,提出了应对措施和方法,确保分析结果准确可靠。试验结果表明:石墨管的性能随测定次数、溶液酸度、原子化温度和时间等的变化而改变,其性能的改变对铅石墨炉分析结果影响较大,采用标准溶液校正、控制酸用量、一管专用和涂层石墨管等方法,可有效消除或减少干扰。分别进行了国家标准物质(茶叶GBW07605)和几种水果蔬菜样品的标准回收测定,结果表明:标准物质中铅的测定结果在标准规定范围内,样品标准回收率为(100+10)%。

The graphite tube atomic absorption signals of different determination times, relevant technical indexes and surface structure changes were analyzed using graphite furnace atomic absorption spectrometry and scanning electron microscope observation method to study the effect of graphite tube functional change on determination of the lead in non-polluted fruits and vegetables as well as the occurrence pattern. Countermeasures were put forward to ensure the accuracy and reliability of the analyzing results. Experiments showed that the function of graphite tube changed with the change of determination time, solution acidity, atomization temperature and time, and etc. The functional change of the graphite tube had great influence on the analyzing results. The influence was effectively reduced or eliminated using the methods such as standard solution adjusting, controlling the acid quantity, using one tube for specific purpose and using graphite tube with a coating. Standard recovery tests were made respectively of a national standard product （ tea GBW07605 ） and samples of several fruits and vegetables. The results showed that the determination results of lead in the standard product were within the range stipulated by the standard, and the standard recovery rates of the samples were 100±10%.