紫外分光光度法测定总氮空白值过高原因分析

碱性过硫酸钾消解紫外分光光度法测定总氮过程中，常常发生空白值过高而影响测定的情况，可能造成空白值过高的原因很多．主要包括纯水质量、试剂纯度、实验条件等几个方面，通过对可能造成总氮测定空白值过高的各项原因进行逐一系统分析和试验．发现造成空白值过高的原因主要为试剂过硫酸钾纯度不够，含有的总氮杂质过高所致，采用二次重结晶的方法时过硫酸钾试剂提纯后使用。同时严格地按照标准方法要求控制实验条件，即可大大降低总氮测定的空白值。

Reason Analysis of High Blank Value in Determination of Total Nitrogen by UV Spectrophotometric Method

The blank value used to be high when the total nitrogen was determined by alkaline potassium persulfate digestion-UV spectrophotometric method.The reasons that could cause high blank value include water quality,reagent purity,experiment conditions and so on.All kinds of factors that could cause high blank value in measuring the total nitrogen were analyzed and tested in turn.The results indicate that impure potassium persulfate is the main reason caused high blank value.Through secondary recrystallization o...