水中总氮测定方法的改进

针对目前总氮测定方法GB11894—89消解过程中存在的不安全因素、消解不彻底、双波长测定重现性差等缺点，以水热反应釜代替比色管、烘箱代替高压锅进行消解，并结合酚二磺酸分光光度法对硝酸盐氮的测定进行了改进。采用改进后的方法测定水中的总氮，其相关系数为0．9999，加标回收率为98％～103％，RSD〈5％。试验证明，改进后的方法优化了消解环境，提高了总氮测定方法的稳定性，且灵敏度、准确度、精密度等均令人满意。

Improvement of Determination Method of Total Nitrogen in Water

The present total nitrogen determination method has some disadvantages, such as insecurity, incomplete digestion, poor repeatability of double wavelength determination and so on. The digestion was conducted by replacing colorimetric cylinder with hydrothermal reaction kettle, and autoclave with dry oven, and the determination of nitrate nitrogen was improved based on spectrophotometry with phenol disulfonic acid. When the total nitrogen in water is determined with the improved method, the correlation coefficient is 0. 999 9, the recovery rate of standard addition is 98% to 103%, and the relative standard deviation is less than 5%. The results show that the improved method optimizes the digestion condition, improves the stability of total nitrogen determination method, and the sensitivity, accuracy and precision are satisfactory.