Monser L, Sadok S, Greenway G M, Shah I, Uglow R F
Institut National des Sciences Appliquées et de Technologie, Centre Urbain Nord, B.P. No. 676, 1080 Tunis Cedex, Tunisia.
Talanta. 2002 May 24;57(3):511-8. doi: 10.1016/s0039-9140(02)00057-7.
A direct spectrophotometric flow injection method for the simultaneous determination of nitrite and nitrate has been developed. The method is based on the oxidation of a phosphomolybdenum blue complex by the addition of nitrite and the decrease in absorbance of the blue complex is monitored at 820 nm. The injected sample is split into two segments. One of the streams was directly reacted with the above reagent and detected as nitrite. The other stream was passed through a copperised cadmium reductor column where reduction of nitrate to nitrite occurs, and the sample was then mixed with the reagent and passed through the cell of the spectrophotometer to be detected as nitrite plus nitrate. The conditions for the flow injection manifold parameters were optimised by experimental design and the concentration of nitrite and nitrate was determined in the linear range from 0.05 to 1.15 mug ml(-1) nitrite and 0.06 to 1.6 mug ml(-1) nitrate with a detection limit of 0.01 mug ml(-1) for nitrite and 0.025 mug ml(-1) for nitrate. The method is suitable for the simultaneous determination of nitrite and nitrate in fish and water samples with a sampling rate of 25+/-2 sample per hour.
已开发出一种直接分光光度流动注射法同时测定亚硝酸盐和硝酸盐。该方法基于通过添加亚硝酸盐氧化磷钼蓝络合物，并在820nm处监测蓝色络合物吸光度的降低。注入的样品被分成两段。其中一股流直接与上述试剂反应并作为亚硝酸盐进行检测。另一股流通过镀铜镉还原柱，在此处硝酸盐还原为亚硝酸盐，然后样品与试剂混合并通过分光光度计的比色皿，作为亚硝酸盐加硝酸盐进行检测。通过实验设计优化了流动注射歧管参数的条件，亚硝酸盐和硝酸盐的浓度在0.05至1.15μg ml(-1)亚硝酸盐和0.06至1.6μg ml(-1)硝酸盐的线性范围内测定，亚硝酸盐的检测限为0.01μg ml(-1)，硝酸盐的检测限为0.02 fiveμg ml(-1)。该方法适用于同时测定鱼和水样中的亚硝酸盐和硝酸盐，采样率为每小时25±2个样品。
