河口岸带氨氮原位快速分析方法研究

In situ rapid analytical method for ammonia nitrogen concentration in estuarine zone

以自主研发的海水氨氮原位快速分析仪的现场可靠测量为目标,基于改进的靛酚蓝分光光度法建立了一种河口岸带氨氮的快速分析方法。论文基于正交实验分析,研究了不同盐度条件下,全自动快速测量最佳不完全显色反应时间,并确定了给定盐度范围内最佳不完全显色反应时间随盐度变化的规律。研究及分析结果表明,样品盐度为5‰的情况下,基于改进和优化后的靛酚蓝分光光度法,氨氮原位测量仪的检测耗时仅需要60s左右;样品盐度在0‰~25‰范围内,氨氮快速测量的最佳反应时间,随着盐度的增大而逐渐增加,样品盐度为25‰时,检测耗时为180s。光程长度为10cm、显色反应时间为60s时,盐度为5‰的氨氮样品检测下限为0.9945μmol·L^(-1),方法标准工作曲线R2大于0.99,证明改进后的靛酚蓝分光光度法可以满足河口岸带水体中氨氮的原位快速检测。将其应用于湛江湾水体中氨氮时间序列在线监测发现,监测期间氨氮浓度与水体盐度存在很好的负相关关系。与传统的人工检测和流动注射分析方法相比,自主研发的海水氨氮原位快速分析仪检测分析过程中样品和试剂消耗量极少(μL),反应时间短(盐度为5‰时60 s),可适用于河口岸带水体中氨氮的长时间序列原位及在线监测。

With the goal of in situ reliable measuring of the ammonia nitrogen by a self-developed in situ analyzer,a rapid analysis method for ammonia nitrogen concentration in estuarine zones has been established based on the improved indophenol blue spectrophotometry.Through the orthogonal experimental analysis on the incomplete chromogenic reaction time and salinity,the optimal incomplete chromogenic reaction time for in situ automated rapid measurements under different salinity conditions has been established and the variation of the optimal incomplete chromogenic reaction time of the samples with salinity in each range has been determined.The study shows that the optimal reaction time for the rapid measurement of ammonia nitrogen in the range of salinity from 0‰to 25‰gradually increases with the increase of salinity and the minimum reaction time is 60s(salinity:5‰)and the maximum reaction time is 180s(salinity:25‰).With a 10 cm LWCC(liquid waveguide capillary cell)and 60s reaction time,the detection limit of this method acquired by taking 11 parallel samples of blank samples is 0.9945μmol·L−1(salinity:5‰),and the R2 of the standard working curve of the method was more than 0.99,which proved that the improved indophenol blue spectrophotometric method can meet the in situ rapid analysis of ammonia nitrogen in estuarine zones.The in situ analyzer has deployed in the Zhanjiang Bay for the time series monitoring of ammonia nitrogen concentration,and the monitoring data revealed that there is a good negative correlation between the ammonia nitrogen concentration and the salinity in the Zhanjiang Bay during the monitoring period.The consumption of samples and reagents during the detection and analysis process is very small(μL),and the reaction time is short(60 s,salinity:5‰),and these features make the analyzer ideally suited for long time series monitoring of ammonia nitrogen concentration in estuarine waters.