Graduate School of Biosphere Science, Department of Environmental Dynamics and Management, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima 739-8521, Japan.
Anal Chem. 2009 Aug 15;81(16):6843-50. doi: 10.1021/ac901128y.
The measurement of photochemically generated nitric oxide radicals (NO) in natural waters has long been an arduous task because of a lack of simple analytical techniques, even though the environmental significance of this radical is paramount. We have developed a simple analytical method for the determination of photochemically generated NO in natural waters using 4,5-diaminofluorescein (DAF-2) as a probe compound. This method is based on the reaction of photoformed NO with DAF-2 in air-saturated solution to produce a highly fluorescent triazolofluorescein (DAF-2T) product. DAF-2T was determined by using reversed-phase HPLC with fluorescence detection, with excitation and emission wavelengths of 495 and 515 nm, respectively. Under optimum conditions, the calibration curve exhibited linearity in the range of 0.025-10 nM DAF-2T. The coefficients of variance for the measurements of the signal intensities of DAF-2T (from the photolysis of 0.5 microM and 5 microM NO(2)(-) with DAF-2) were less than 5% and 3%, respectively. For a total irradiation time of 30 min, the detection limit of the photoformation rate of NO was 1.65 x 10(-13) M s(-1), defined as 3sigma of the lowest measured DAF-2T concentration (0.025 nM). The proposed method is relatively unaffected by potential interferents in seawater. The method was employed to determine the photoformation rate of NO in the Seto Inland Sea and the Kurose River in Hiroshima Prefecture, Japan. The measured NO photoformation rates in seawater and river water samples ranged from (5.3-32) x 10(-12) M s(-1) and (9.4-300) x 10(-12) M s(-1), respectively.
在自然水中光化学产生的一氧化氮自由基 (NO) 的测量一直是一项艰巨的任务，因为缺乏简单的分析技术，尽管这种自由基的环境意义至关重要。我们已经开发出一种使用 4,5-二氨基荧光素 (DAF-2) 作为探针化合物的简单分析方法，用于测定自然水中光化学产生的 NO。该方法基于光形成的 NO 与空气饱和溶液中的 DAF-2 的反应，生成高度荧光的三唑荧光素 (DAF-2T) 产物。使用反相 HPLC 与荧光检测，激发和发射波长分别为 495nm 和 515nm，测定 DAF-2T。在最佳条件下，DAF-2T 的校准曲线在 0.025-10 nM 范围内呈线性。DAF-2T 信号强度测量的变异系数（分别来自 0.5 和 5 microM NO2-与 DAF-2 的光解）小于 5%和 3%。对于 30 分钟的总辐照时间，NO 光形成速率的检测限为 1.65 x 10(-13) M s(-1)，定义为最低测量的 DAF-2T 浓度（0.025 nM）的 3sigma。该方法受海水中潜在干扰物的影响较小。该方法用于测定日本广岛县濑户内海和黑濑川的 NO 光形成速率。海水中和河水中样品的测量 NO 光形成速率范围分别为（5.3-32）x 10(-12) M s(-1)和（9.4-300）x 10(-12) M s(-1)。
