以茶叶中铅为例的实验室内部质控样的制备及评价探讨

Preparation and evaluation of laboratory internal quality control sample taking lead in tea as an example

目的制备以茶叶中铅为例混合均匀、性质稳定的内部控制样。方法取干燥均匀的绿茶粉碎、过筛,分组,采用单因子方差分析法(F检验法)进行均匀性分析,t检验法进行稳定性分析,采用质控样检测和加标回收验证结果准确性。结果 F检验法中,计算的F值为0.669<3.02,即F<F临界值,表明在0.05显著性水平时,样品中的铅是均匀的;t检验法中,计算的t_1值为0.420,t_2值为0.946,t_3值为1.185,t_1、t_2、t_3均小于2.571,即t<t_(0.05(5))临界值,表明在0.05显著性水平时,茶叶样品中的铅是稳定的;质控样检测和加标回收结果证明检测结果准确无误。结论在条件成熟的情况下,实验室可以自行制备混合均匀、性质稳定的内部控制样,在节约成本的基础上开展内部质量控制。

Objective To prepare a stable internal control sample taking lead in tea as an example. Methods Dry and uniform green tea was crushed, sieved and grouped. The uniformity of the sample was analyzed by one-way ANOVA （F-test） and its stability was analyzed by t-test. The accuracy of the test results was evaluated by measuring its quality control copies and recoveries. Results The F value was 0.669, which was less than the critical value of 3.02, and it meant that the lead in the sample was uniform at 0.05 significant level. The h value was 0.420, t2 value was 0.946, and t3 value was 1.185, which were all less than the t0.05（5） critical value of 2.571, and it indicated that the lead in tea sample was stable at 0.05 significant level. The quality control sample test and the result of the additive recovery proved that the test results were correct. Conclusion Uniform and stable internal control sample can be prepared in laboratory. By this way, the internal quality control can be conducted on the basis of cost saving.