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目的探究石墨炉原子吸收光谱法测定茶叶中铅的最佳试验条件,建立测定茶叶中铅的准确测定方法。方法样品采用微波消解法进行消解,同时应用L_(16)(4~5)正交表安排石墨炉原子吸收法测定过程中的灰化温度、灰化时间、原子化温度、原子化时间和基体改进剂浓度五个因素进行试验,优化仪器的各项操作参数,考察灰化温度、灰化时间、原子化温度、原子化时间和基体改进剂浓度5个因素的各项性能指标,建立石墨炉原子吸收光谱法准确测定茶叶中铅的最优条件。结果石墨炉原子吸收光谱法测定茶叶中铅的最佳条件是:灰化温度和原子化温度分别是900℃和1500℃,灰化时间和原子化时间分别为10 s和3 s,基体改进剂浓度为1.50%,实验的RSD为2.70%~3.90%,回收率为97.50%~101.20%,检出限为0.04 mg/kg。结论采用微波消解法,同时利用正交试验设计优化实验条件可以提高工作质量和效率,所建立的方法准确、灵敏、简便可行,是测定茶叶中铅含量的可靠方法。
Objective To explore the best experimental conditions for the determination of lead in tea by graphite furnace atomic absorption spectrometry and to establish an accurate method for the determination of lead in tea. Methods The samples were digested by microwave digestion method. At the same time, the ashing temperature, the time of ashing, the atomization temperature, the atomization time and the matrix were determined by graphite furnace atomic absorption spectrometry with L_ (16) (4 ~ 5) Improver concentration of five factors to test, optimize the operating parameters of the instrument, study the ash temperature, ashing time, atomization temperature, atomization time and matrix modifier concentration of five factors of various performance indicators, the establishment of graphite furnace Accurate Determination of Lead in Tea by Atomic Absorption Spectrometry. Results The optimum conditions for determination of lead in tea by graphite furnace atomic absorption spectrometry were: ashing temperature and atomization temperature were 900 ℃ and 1500 ℃ respectively, ashing time and atomization time were 10 s and 3 s respectively, The concentration was 1.50%. The RSD of the experiment was 2.70% ~ 3.90%. The recoveries were 97.50% ~ 101.20%. The detection limit was 0.04 mg / kg. Conclusion The method of microwave digestion and the optimization of experimental conditions by orthogonal design can improve the working quality and efficiency. The established method is accurate, sensitive and simple and feasible, which is a reliable method to determine the content of lead in tea.