A simple and precise method for measuring ammonium in marine and freshwater ecosystems
A simple and precise method for measuring ammonium in marine and freshwater ecosystems
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DOI：
10.1139/cjfas-56-10-1801
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发表时间：
1999-10-01
影响因子：
2.4
通讯作者：
Peterson, BJ
中科院分区：
文献类型：
--
作者：
Holmes, RM;Aminot, A;Peterson, BJ
准确测定铵态氮浓度是了解水生态系统中氮素地球化学的基础。不幸的是，通常使用的靛酚蓝方法经常产生不一致的结果，特别是当铵浓度低时。在这里，我们提出了一种荧光法，给出了精确的测量铵在很宽的范围内的浓度和盐度强调亚微摩尔水平。该方法不仅解决了分析问题，而且大大简化了样品的收集和保存。它使用单一的工作试剂（由邻苯二甲醛，亚硫酸钠和硼酸钠组成），在黑暗中储存时可稳定数月。工作试剂和样品可在样品采集后立即混合，反应在室温下3 h内完成。可以校正基质效应和背景荧光而不会引入实质性误差。这种简单的方法即使在非常低的铵浓度下也能产生高度可重复的结果。
The accurate measurement of ammonium concentrations is fundamental to understanding nitrogen biogeochemistry in aquatic ecosystems. Unfortunately, the commonly used indophenol blue method often yields inconsistent results, particularly when ammonium concentrations are low. Here, we present a fluorometric method that gives precise measurements of ammonium over a wide range of concentrations and salinities emphasizing submicromolar levels. The procedure not only solves analytical problems but also substantially simplifies sample collection and preservation. It uses a single working reagent (consisting of orthophthaldialdehyde, sodium sulfite, and sodium borate) that is stable for months when stored in the dark. The working reagent and sample can be mixed immediately after sample collection and the reaction proceeds to completion within 3 h at room temperature. Matrix effects and background fluorescence can be corrected without introducing substantial error. This simple method produces highly reproducible results even at very low ammonium concentrations.