不同方法测定水体总氮存在的问题探讨及条件优化研究

Discussion and Optimization on Existing Problems in Determining Total Nitrogen in Water by Different Methods

利用碱性过硫酸钾消解紫外分光光度法,探讨了消解时间和消解温度对空白吸光值的影响,认为增加消解时间可以降低空白吸光值,而提高消解温度对空白吸光值的影响不大;对于某些样品中总氮含量低于氨氮含量的现象,将碱性过硫酸钾装入小试管,再放入装有水样的比色管中,虽然能够减少氨气形式逸出的氮含量,但回收率较低;连续流动和流动注射-盐酸萘乙二胺分光光度法,在以后的修订中应增加过硫酸钾含氮量以及镉柱还原能力大小的界定。

The problem of high blank absorption value in alkaline potassium persulfate digestion- UV ultraviolet spectrophotometry has been discussed from two aspects of digestion time and temperature. The result show that increasing the digestion time can reduce the absorbance of blank samples,but improving the digestion temperature has little effect on the absorption value. For samples with lower total nitrogen content than the concentration of ammonia nitrogen,the alkaline potassium persulfate solution is firstly filled in a small test tube and then put in the colorimetric tube with water samples,which can reduce the ammonia escape,but the recovery rate is low. For continuous flowing naphthyl ethylenediamine dihydrochloride spectrophotometric method and flowing injection- naphthyl ethylenediamine dihydrochloride spectrophotometric method,the nitrogen content of potassium persulfate and the definition of cadmium column reduction capacity should be determined in the subsequent revision.