基于休哈特控制图(SCC)对ICP-OES性能评价的方法研究

Reseach on Evaluation of Performance of ICP-OES by Shewhart Control Chart(SCC)

连续五年用中国计量科学研究院研制的标准溶液对等离子体发射光谱仪(ICP-OES)进行监测,建立一种基于休哈特控制图(SCC)对仪器性能进行核查、校准和评价的方法,以确保测试数据的有效性。结果表明,灵敏度较高的元素如Cu和Ba等元素检出限五年中有上升趋势,其余四元素为正常模式或周期模式。六元素重复性指标均无明显上升或下降趋势。经相关分析,各元素两两之间重复性指标均正相关;Zn、Mn两元素相关性较高(r=0.942);Zn、Ba元素相关性较低(r=0.654),其余元素相关性介于两者之间。通过对判据异常点Zn检出限的分析,表明某些符合检定规程要求的指标,也有可能是异常点。通过建立控制图的方法可有效对仪器性能进行评价和证明,弥补规程周期长等缺点,便于及时发现和解决测试中的问题,对类似仪器也有借鉴意义。

Performance of Inductively coupled plasma optical emission spectrometer （ICP-OES） was measured in the past five years by standard solution from National Institute of Metrology （NIM）. Shewhart Control Chart （SCC） was used to check and calibrate the performance to ensure the validity of data. The result showed that detection limit of element Copper and Barium with higher sensitivity were not as good as before while others or relative standard deviation （RSD） of all the elements keep fit in normal or periodic model. Correlation analysis of RSD showed that Zn ＆ Mn was higher （r=0.942）, while Zn ＆ Ba was lower （r=0.654）. By analysis of outliers, control chart was proved more efficiently to find problems, compensating the drawbacks of verification rules. The method might be helpful for other similar instruments.