Burakham Rodjana, Oshima Mitsuko, Grudpan Kate, Motomizu Shoji
Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand.
Talanta. 2004 Dec 15;64(5):1259-65. doi: 10.1016/j.talanta.2004.03.059.
A novel spectrophotometric reaction system was developed for the determination of nitrite as well as nitrate in water samples, and was applied to a flow-injection analysis (FIA). The spectrophotometric flow-injection system coupled with a copperised cadmium reductor column was proposed. The detection was based on the nitrosation reaction between nitrite ion and phloroglucinol (1,3,5-trihydroxybenzene), a commercially available phenolic compound. Sample injected into a carrier stream was split into two streams at the Y-shaped connector. One of the streams merged directly and reacted with the reagent stream: nitrite ion in the samples was detected. The other stream was passed through the copperised cadmium reductor column, where the reduction of nitrate to nitrite occurred, and the sample zone was then mixed with the reagent stream and passed through the detector: the sum of nitrate and nitrite was detected. The optimised conditions allow a linear calibration range of 0.03-0.30mug NO(2)(-)-Nml(-1) and 0.10-1.00mug NO(3)(-)-Nml(-1). The detection limits for nitrite and nitrate, defined as three times the standard deviation of measured blanks are 2.9ng NO(2)(-)-Nml(-1) and 2.3ng NO(3)(-)-Nml(-1), respectively. Up to 20 samples can be analyzed per hour with a relative standard deviation of less than 1.5%. The proposed method could be applied successfully to the simultaneous determination of nitrite and nitrate in water samples.
开发了一种用于测定水样中亚硝酸盐和硝酸盐的新型分光光度反应系统，并将其应用于流动注射分析（FIA）。提出了一种与镀铜镉还原柱联用的分光光度流动注射系统。检测基于亚硝酸根离子与间苯三酚（1,3,5-三羟基苯）（一种市售酚类化合物）之间的亚硝化反应。注入载流中的样品在Y形连接器处被分成两股流。其中一股流直接合并并与试剂流反应：检测样品中的亚硝酸根离子。另一股流通过镀铜镉还原柱，在那里硝酸盐被还原为亚硝酸盐，然后样品区与试剂流混合并通过检测器：检测硝酸盐和亚硝酸盐的总和。优化后的条件使线性校准范围为0.03 - 0.30μg NO(2)(-)-Nml(-1)和0.10 - 1.00μg NO(3)(-)-Nml(-1)。亚硝酸盐和硝酸盐的检测限（定义为测量空白标准偏差的三倍）分别为2.9ng NO(2)(-)-Nml(-1)和2.3ng NO(3)(-)-Nml(-1)。每小时可分析多达20个样品，相对标准偏差小于1.5%。所提出的方法可成功应用于水样中亚硝酸盐和硝酸盐的同时测定。
