硝酸盐快速测定方法研究

Study on Rapid Determination of Nitrate

为了快速测定硝酸盐含量,本研究配制不同浓度的硝酸盐溶液,分别采用锌粉和镉粉作为还原剂,将硝酸盐还原为亚硝酸盐,经重氮偶合反应后生成粉红色偶氮染料,进行比色。同时,在河南农大迅捷测试技术有限公司原有方法的基础上,进行了还原剂、显色剂、显色时间等的一系列优化试验。结果表明,用镉粉作还原剂,分别加入硝态氮掩蔽剂4滴、硝态氮助掩剂10滴、硝态氮还原剂6滴、硝态氮显色剂9滴,沸水浴显色5 min的试验结果最好。同用锌粉作还原剂相比,用镉粉作还原剂的吸光度平均提高了29.8倍,且相关系数提高了0.014,解决了硝态氮测定过程中吸光度过低的问题。

For the rapid determination of nitrate content,this study made up different concentrations of nitrate solution,zinc powder and cadmiumpowder were used as the reducing agent to reduce nitrate to nitrite,and colorimetric analysis of diazo coupling reaction was conducted after theformation of a pink azo dyes. At the same time,based on the original method of Henan Agricultural University Xunjie Test Technology Co.,Ltd.,a seriesof optimization experiments were selected,such as reducing agent,chromogenic agent,chromogenic time,etc. The results showed that the optimumcondition was as follow:using cadmium powder as reducing agent,respectively adding 4 drops nitrate nitrogen masking agent,10 drops nitrate maskingagent,6 drops nitrate reducing agent,9 drops nitrate reagent and then boiling water bath for 5 min.The correlation between absorbance andconcentration by using cadmium powder as reducing agent was 0.014 higher than by using zinc powder as reducing agent,and the absorbance improved29.8 times.This method can solve the problem caused by the low absorbance in the process of determination of nitrate nitrogen.