化学需氧量标准溶液的配置及不确定度评定

Configuration and Uncertainly Assessment of Chemical Oxygen Demand(COD)Standard Solution

首先,依据JJG 1012—2019《化学需氧量(COD)在线自动监测仪检定规程》,通过对邻苯二甲酸氢钾二级纯度有证标准物质进行稀释和定容,配置出1000 mg/L的化学需氧量标准溶液;然后,对配置过程中标准物质的质量引入的相对不确定度、标准物质的纯度引入的相对不确定度、标准溶液体积引入的相对不确定度和各不确定度的分量进行分析及评定,得到符合检定规程要求的标准溶液和对应的扩展不确定度;最后,依据检定规程的环境要求将配置出的标准溶液密封保存,为后期配置其低浓度的COD标准溶液提供了先决条件。

Firstly,according to JJG 1012—2019“Verification Regulation of On-line Automatic Determinators of Chemical Oxygen Demand(COD)”,the standard solution of COD of 1000 mg/L is prepared by diluting and constant-volume determination of certified reference material of secondary purity potassium hydrogen phthalate.Then,the relative uncertainty introduced by the quality of the standard material,the relative uncertainty introduced by the purity of the standard material,the relative uncertainty introduced by the volume of the standard solution in the configuration process and the components of each uncertainty are analyzed and evaluated,and the standard solution and the corresponding extended uncertainty which meet the requirements of the verification regulation are obtained.Finally,the configured standard solution is sealed and stored according the environmental requirements of the verification regulations,which provides a prerequisite for the later configuration of its low concentration COD standard solution.