流动注射法测定咸水和半咸水中的硝酸盐氮和亚硝酸盐氮

咸水、半咸水资源广布，是干旱、半干旱地区重要的替代水资源和锂、钾盐等国家战略性矿产资源的重要来源。对咸水、半咸水中硝酸盐和亚硝酸盐等关键指标进行监控，是实现水资源综合利用的重要前提。流动注射法集采样、富集、分离、检测于一体，能够实现在线检测分析，近年来被广泛应用于淡水和海水分析，但对盐度更高的咸水类样品，该法尚未开展深入研究。本文利用全自动流动注射分析仪，建立了适用于咸水和半咸水中硝酸盐氮和亚硝酸盐氮的分析测定方法。通过仪器工作参数、显色剂浓度和介质、缓冲溶液中氯化铵浓度和pH值等实验条件优化，确定了方法最佳试验参数。
用纯水作载流，可以实现盐度为0～5%范围水样中硝酸盐氮和亚硝酸盐氮的准确测定。对于盐度大于5%的卤水样品，需采用载流盐度匹配的方式改善样品回收率，使该法对盐度的耐受范围扩展至24%左右。本法对硝酸盐氮和亚硝酸盐氮的检出限分别为0.002mg/L、0.001mg/L，测定范围分别为0～2.00mg/L、0～1.00mg/L。通过国家标准物质和实际样品分析表明，该法具有良好的精密度和正确度，自动化程度高，分析周期短，适用于大批量样品的分析测试。

Determination of Nitrate Nitrogen and Nitrite Nitrogen in Brackish and Saline Waters by Flow Injection Analysis

BACKGROUNDSaline water and brackish water resources are widely distributed, which are important alternative water resources in arid and semi-arid areas. They are also important sources of national strategic mineral resources such as lithium and potassium salts. Monitoring the key indicators such as nitrate and nitrite in saline water and brackish water is an important prerequisite for the comprehensive utilization of water resources. There are various methods for determining nitrates and nitrites, including spectrophotometry, fluorescence, chemiluminescence, electrochemistry, chromatography, and flow injection analysis.
Among them, chromatography and electrochemistry require expensive and complex instruments or reagent; while spectrophotometry, although using simple equipment, has complex manual operation. Flow injection analysis is an analytical method that integrates sampling, enrichment, separation, and detection and can be used to achieve online detection and analysis. It has been widely used in freshwater and seawater analysis, but for saline water samples with higher salinity, the method has not been studied in depth.