紫外分光光度法测定水质总氮的影响因素分析

Analysis of Influencing Factors Affecting Total Nitrogen in Water by UV Spectrophotometry

总氮是湖泊、水库水质营养状态评价不可缺少的指标之一,在监测工作中常采用碱性过硫酸钾消解紫外分光光度法测定总氮。该经典方法在实际测定过程中,会遇到空白值偏高、测量结果重复性不够好、准确度不够好等问题。本文从比色管筛选、过硫酸钾试剂、实验用水、消解温度、消解时间、冷却时间、待测样品的稀释、波长定位准确性及避免其它污染带来的影响等多方面因素进行讨论分析,得出总氮测定时须特别注意的影响因素。

Total nitrogen is one of the indispensable indexes for evaluating the water quality of lake and reservoir. In the monitoring work, the total nitrogen is determined by alkaline potassium sulfate digestion and ultraviolet spectrophotometry. Using classical method in the actual measurement process,some problems exist,such as the blank value is high,the measurement result is not good repeatability,accuracy is not good enough,and so on. The factors affecting the total nitrogen determination were discussed from many aspects,such as the screening of the color temperature,the reagent,the water consumption,the temperature,the time of digestion,the cooling time,the dilution of the sample,the accuracy of wavelength positioning,and the effects of avoiding other pollution.