紫 外 分 光 光 度 计 法 测 定 硝 化 纤 维 素 含 氮 量

A green non-toxic，easy and accuracy analysis method of the nitrogen content in nitrocellulose（NC）was investigated by using ultraviolet spectrophotometer，which was based on a linear relationship between the nitrogen content of NC and the molar ratio of nitrite-to-nitrate ions released after alkaline hydrolysis. Under the same reaction condition，five NC standard samlpes with known nitrogen contents were hydrolyzed. The concentrations of NO₂^- and NO₃^- in the hydrolysate were measured by the ultraviolet spectrophotometer，and the reaction condition of measuring system was optimized. The linear relationship between the nitrogen content of NC standards（x）and the molar ratio of nitrite-to-nitrate ions（y）was determined by the least squares method. Finally，three NC samples were used to evaluate the proposed method. Results show that the concentration of NO₂^- and NO₃^- in alkaline hydrolysate can be measured simultaneously by ultraviolet spectrophotometer，and the most suitable reaction condition is as follows：the concentration of sulfamic acid of 20 g·L^-1，and the process time of 30 min. Under the optimal reaction condition，the linear relationship between x and y is obtained，and the R² is 0.9893. The verification results of NC_A，NC_B and NC_C reveal that the nitrogen content determined by ultraviolet spectrophotometer and actual nitrogen contents are in good agreement. The relative standard deviation（n=4）values are all less than 0.150%.