碱性过硫酸钾法测定水中总氮的关键因素及质量控制研究

Research on the Key Factors and Quality Control of Detecting Total Nitrogen in Water by Alkaline Potassium Persulfate Method.

本文从实验室质量控制角度对过硫酸钾纯度和碱性过硫酸钾保存条件、实验用水、消解时间等碱性过硫酸钾法测定水中总氮的影响因素进行探讨并优化实验条件。利用GraphPad Prism统计软件对各影响因素下的数据进行有无显著性差异检验从而确定关键因素。在最佳实验条件下首次研究平行双样R-图的质量控制图在养殖尾水总氮监测中的应用,对城市杂用水、生活污水、工业废水、原水和养殖尾水五类水体进行精密度、准确度分析,同时对五类水体总氮含量与现有标准排放限值进行比对。结果表明,影响总氮测定的关键因素为过硫酸钾纯度。初步建立养殖尾水总氮平行双样R-图的质量控制图,使监测大批量样品过程可控。该方法性能(精密度、准确度)均符合国家标准方法要求,适用于以上五类水体的总氮监测。

In this paper,the influencing factors of alkaline potassium persulfate method for the determination of total nitro⁃gen in water such as purity of potassium persulfate,alkaline potassium persulfate solution storage conditions,experimental water and digestion time are discussed from the perspective of laboratory quality control,and the experimental conditions are optimized.The GraphPad Prism statistical software is used to test whether there are significant differences in the data under various influencing factors so as to identify the key factors.Under the best experimental conditions,the application of the quality control chart of parallel double-sample R-chart in the monitoring of total nitrogen in aquaculture tail water is studied for the first time.The precision and accuracy analysis of five kinds of water bodies,including urban miscellaneous water,domestic sewage,industrial wastewater,raw water and aquaculture tail water are researched.Meanwhile,the total ni⁃trogen content of five types of water bodies is compared with the current standard emission limits.It turns out the key factor affecting the determination of total nitrogen is the purity of potassium persulfate.The quality control chart of parallel dou⁃ble-sample R-chart of total nitrogen in aquaculture tail water is initially established to make the process of monitoring large quantities of samples controllable.The method performance(precision and accuracy)all meet the National Standard Meth⁃od request and it is suitable for monitoring total nitrogen in the above five types of water bodies.