简析氨氮测定中4种异常现象及消除方法

Analysis of Four Abnormal Phenomena and Countermeasures for Ammonia Nitrogen Determination

摘要: 氨氮是水环境监测中评价水体污染状况与生态自净能力的核心指标，其检测结果是水环境评价、污染管控及治理决策科学性的重要依据。纳氏试剂分光光度法凭借操作简便、灵敏度高、适用范围广等优势，被广泛应用于地表水、地下水、生活污水及工业废水的氨氮检测工作。但在日常检测中，受试剂质量、水样保存条件、实验用水、水样基质特性以及操作规范性等多重因素影响，测定环节常出现空白值偏高、显色液分层、红色颗粒沉淀、深红棕色絮凝物生成等典型异常情况，此类问题会破坏显色体系稳定性，引发吸光度偏移、测定结果失真，进而降低监测数据的精密度与准确度。本文依托环境监测一线工作实践，系统归纳纳氏试剂分光光度法测定氨氮时出现的四类典型异常现象，从反应机理、试剂特性、水样干扰及操作流程等角度剖析异常成因。结合对照实验验证，提出针对性强、切实可行的干扰消除措施，并完善全过程质量控制要点，为提升氨氮检测工作质量、保障监测数据真实可靠提供实践参考。

Abstract: Ammonia Nitrogen is a core indicator for assessing water pollution status and ecological self-purification capacity in water environmental monitoring, and its detection results underpin the scientificity of water environment evaluation, pollution control and remediation decision-making. Nessler’s reagent spectrophotometry is widely used for ammonia Nitrogen determination in surface water, groundwater, domestic sewage and industrial wastewater due to its simple operation, high sensitivity and wide applicability. In routine detection, however, multiple factors including reagent quality, sample preservation, experimental water, water sample matrix and operational standardization frequently induce typical anomalies such as elevated blank values, chromogenic solution stratification, red particulate precipitation and dark reddish-brown flocculation. These anomalies destabilize the chromogenic system, trigger absorbance drift and result in distorted measurements, thereby degrading the precision and accuracy of monitoring data. Based on front-line environmental monitoring practice, this paper summarizes four typical abnormal phenomena in ammonia Nitrogen determination via Nessler’s reagent spectrophotometry. The underlying causes are analyzed from the aspects of reaction mechanism, reagent property, water sample interference and operational procedure. Supported by control experiments, targeted and practicable interference elimination measures are proposed, together with improved whole-process quality control protocols. This study provides practical reference and technical support for enhancing ammonia Nitrogen detection quality and guaranteeing the authenticity and reliability of monitoring data.