控制图在铜精矿中银含量检测质控管理中的应用

目前,测量不确定度的评估技术大致可以分为两类:“bottom-up”和“top-down”。“bottom-up”技术过程繁复且对化学检测实验室测量不确定度有局限性,而“top-down”技术中的控制图法不仅操作简便,还可以弥补“bottom-up”技术评定不确定度出现的局限性,控制图法作为实验室质控管理的重要手段已被广泛认可。依据标准GB/T 27407—2010,探讨了控制图在铜精矿中银含量检测质控管理的应用,对实验室日常分析工作中铜精矿质控标准样品(GBW 07166)中银含量系列结果的正态性、独立性与分辨力进行检验,作控制图,t检验并评定方法的不确定度及分析其合理性。铜精矿中银含量质控样品实测数据控制图的计算结果如下:平均值为43.8g/t,期间精密度为1.6g/t,扩展不确定度为3.2g/t,接受系列测量结果的正态性、独立性与分辨力适应性的假定,控制图中没有失控点,整个实验室检测系统处于受控状态。控制图法可反映实验室较长一段时间内的检测水平,适用于检测实验室的质量控制,具有实际应用价值。

Application of control chart in quality control management during determination of silver in copper concentrate

At present, the evaluation technologies for uncertainty of measurement can be roughly divided into two groups: “bottom-up” and “top-down”. The procedures of “bottom-up” technique are complex and it has limitation in evaluation of measurement uncertainty in chemical testing laboratories. The operation of control chart method in “top-down” technique is easy, and meanwhile it can make up the limitation of “bottom-up” technique in evaluation of measurement uncertainty. As an important approach for laboratory quality control management, the control chart method has been widely recognized. According to national standard GB/T 27407—2010, the application of control chart in quality control management during determination of silver content in copper concentrate was discussed. The normality, independence and resolving ability of measurement results of silver content in standard sample (GBW 07166) were tested in laboratory routine analysis. The control chart was prepared. The uncertainty of method was evaluated by t test and its rationality was analyzed. The calculation results of control chart for silver content determination in quality control sample of copper concentrate were listed as follows: the average value was 43.8g/t, the intermediate precision was 1.6g/t, and the expanded uncertainty was 3.2g/t, which could meet the adaptive hypothesis of normality, independence and resolving ability of measurement results. There was no out-of-control point in control chart, indicating that whole laboratory testing system was in controlled state. The control chart method could reflect the testing level of laboratory within a relatively long period. It was applicable for the quality control of testing laboratory and had practical application value.