针对目前总氮检测设备量程大、检出限高、体积大、废液排量高和测定时间长的问题，以GB 11894—89为理论基础，提出了流动注射法结合分光光度法测定地表水质痕量总氮的方法。通过合理设计检测光程、检测流程和结构布局，合理化量程、检出限和废液排量，同时提高空间利用率和检测效率。对痕量总氮监测系统进行了误差测定实验和数据分析。实验结果表明，量程为0~10 μg/mL、检出限为0.05 μg/mL和相关系数为0.994 55，满足地表Ⅰ~Ⅴ类水质监测要求，对于痕量总氮的测定具有较高的精度，重复性测定的相对标准偏差≤±3.69%，实际水样对比相对误差≤±2.59%。测定时长为25 min，废液排量为27 mL。该系统适用于站房式、试验室和便携式地表水质痕量总氮的测定。

In the light of the current problems of total nitrogen testing equipment such as big measuring range,high detection limit,large volume,high waste liquid discharge and long measuring time,a method for the determination of trace total nitrogen in surface water by flow injection combined with spectrophotometry is proposed on the basis of the theory of GB 11894-89 Water Quality Determination of Total Nitrogen Alkaline Potassium Persulfate Digestion Ultraviolet Spectrophotometry.The measurement range,detection limit and spent liquid discharge are rationalized by designing the detection light path,detection route and layout,and the space utilization rate and detection efficiency are improved at the same time.The error measurement experiment and data analysis are carried out for trace total nitrogen monitoring system.The results show that the measurement range is 0-10 μg·mL^-1,the detection limit is 0.05 μg·mL^-1 and the correlation coefficient is 0.994 55,which meet the monitoring requirements of surface Ⅰ-Ⅴ water quality,and has high accuracy for the determination of trace total nitrogen.The relative standard deviation of repeatability measurement is below ±3.69%.The relative error to the actual water sample is below ±2.59%.25 minutes is spent in the determination and 27 mL of waste liquid is displaced.This system is suitable for determination of total nitrogen in station,laboratory and portable surface water quality.

李文(1975-),男,博士,副教授,硕士生导师,主要从事自动控制、机械自动化、机器人辅助设计和传感器设计