Department of Ocean, Earth and Atmospheric Sciences, Old Dominion University, Norfolk, Virginia 23529, United States.
Anal Chem. 2013 Jul 16;85(14):6661-6. doi: 10.1021/ac400351c. Epub 2013 Jul 2.
Recent studies suggest that cyanate (OCN(-)) is a potentially important source of reduced nitrogen (N) available to support the growth of aquatic microbes and, thus, may play a role in aquatic N cycling. However, aquatic OCN(-) distributions have not been previously described because of the lack of a suitable assay for measuring OCN(-) concentrations in natural waters. Previous methods were designed to quantify OCN(-) in aqueous samples with much higher reduced N concentrations (micromolar levels) than those likely to be found in natural waters (nanomolar levels). We have developed a method to quantify OCN(-) in dilute, saline environments. In the method described here, OCN(-) in aqueous solution reacts with 2-aminobenzoic acid to produce a highly fluorescent derivative, 2,4-quinazolinedione, which is then quantified using high performance liquid chromatography. Derivatization conditions were optimized to simultaneously minimize the reagent blank and maximize 2,4-quinazolinedione formation (>90% reaction yield) in estuarine and seawater matrices. A limit of detection (LOD) of 0.4 nM was achieved with only minor matrix effects. We applied this method to measure OCN(-) concentrations in estuarine and seawater samples from the Chesapeake Bay and coastal waters from the mid-Atlantic region. OCN(-) concentrations ranged from 0.9 to 41 nM. We determined that OCN(-) concentrations were stable in 0.2 μm filtered seawater samples stored at -80 °C for up to nine months.
最近的研究表明，氰酸盐（OCN(-)）可能是水生微生物生长可用的一种重要的还原氮（N）来源，因此可能在水生 N 循环中发挥作用。然而，由于缺乏测量天然水中 OCN(-)浓度的合适方法，水生 OCN(-)分布尚未得到描述。以前的方法是为了在还原 N 浓度（微摩尔水平）远高于天然水（纳摩尔水平）的情况下定量测量 OCN(-)而设计的。我们开发了一种在稀释的咸水环境中定量测量 OCN(-)的方法。在本文描述的方法中，水溶液中的 OCN(-)与 2-氨基苯甲酸反应生成高荧光衍生物 2,4-喹唑啉二酮，然后使用高效液相色谱进行定量。优化了衍生化条件，以同时最小化试剂空白并最大限度地提高在河口和海水中的 2,4-喹唑啉二酮的形成（>90%的反应收率）。在 Chesapeake 湾的河口和大西洋中部沿海地区的海水样本中，检测限（LOD）达到 0.4 nM，只有很小的基质效应。我们应用该方法测量了从切萨皮克湾和大西洋中部沿海地区采集的河口和海水样本中的 OCN(-)浓度。OCN(-)浓度范围为 0.9 至 41 nM。我们确定 OCN(-)浓度在储存在-80°C 下长达九个月的 0.2 μm 过滤海水中是稳定的。
