State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, 361102 Xiamen, Fujian, China.
State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, 361102 Xiamen, Fujian, China.
Talanta. 2018 Mar 1;179:608-614. doi: 10.1016/j.talanta.2017.11.069. Epub 2017 Dec 2.
The indophenol blue (IPB) method based on Berthelot's reaction is one of the most widely used methods for the determination of ammonium in natural waters. This study comprehensively optimized the kinetics of the IPB reaction under different reagent concentrations, temperature and salinity. The normally used toxic and odorous phenol was replaced by the less toxic, stable flaky crystalline compound, o-phenylphenol. With the application of nitroprusside as the catalyst, the reaction can be finished within 20min at room temperature and the formed color compound is stable for 24h. Under the optimized conditions, the method shows high reproducibility (relative standard deviations of 0.64-1.71%, n = 11), highly linear calibration up to 100μM (R = 0.9995, n = 165, 17 days) and a low detection limit of 0.2μM. This method was successfully applied to measure ammonium in estuarine and coastal surface water (n = 63). The results showed insignificant differences with the results obtained using both the standard AutoAnalyzer method and a fluorometric o-phthaldialdehyde method at the 95% confidence level. Compared with previous studies, this method shows the advantages of relatively fast reaction, low toxicity and easy reagent preparation. It is salinity-interference-free and robust (no temperature control is required, reagents can be stored up to 10 days), and suitable for routine analysis under harsh field conditions.
基于 Berthelot 反应的靛酚蓝 (IPB) 法是测定天然水中氨氮最广泛使用的方法之一。本研究全面优化了不同试剂浓度、温度和盐度下 IPB 反应的动力学。通常使用的有毒和有臭味的苯酚被毒性较小、稳定的片状结晶化合物邻苯二酚所取代。应用硝普盐作为催化剂，反应可以在室温下在 20min 内完成，形成的显色化合物在 24h 内稳定。在优化的条件下，该方法具有较高的重现性（相对标准偏差为 0.64-1.71%，n=11），高达 100μM 的线性校准（R=0.9995，n=165，17 天）和低检测限为 0.2μM。该方法成功应用于河口和沿海地表水（n=63）中铵的测定。结果表明，在 95%置信水平下，与标准 AutoAnalyzer 法和荧光邻苯二醛法的结果相比，无显著差异。与以往的研究相比，该方法具有反应速度较快、毒性较低、试剂制备简单、无盐度干扰、稳定性强（无需温度控制，试剂可储存 10 天）等优点，适用于恶劣野外条件下的常规分析。
