采用电位滴定法测定石油馏分中的碱性氮

Determination of basic nitrogen in petroleum fraction by potentiometric titration method

采用电位滴定法测定石油馏分中的碱性氮质量分数(X),优选了试样溶剂及滴定条件,并考察了该方法的准确性和精密度。结果表明:优选试样溶剂为二甲苯-冰乙酸混合溶液;高氯酸标准滴定溶液摩尔浓度为0.02 mol/L,试样溶剂体积为80 m L,X小于100×10-6时滴定间隔体积为0.02 m L,X大于100×10-6时滴定间隔体积为0.05 m L;X的检测范围为(80~2 000)×10-6,加标回收率为91.1%~121.0%;重复性限(r)及再现性限(R)的精密度经验公式为r=0.063 X+1.240,R=0.200 X-8.440。

The mass fraction of basic nitrogen （X） in petroleum fraction was determined by potentiometric titration method, the sample solvent and titration conditions were optimized, and the accuracy and precision of the method were investigated. The results showed that the xylene - ice acetic concentration of 0.02 mol/L, the titration interval optimum sample solvent was acid mixture solution, the molar perchlorate standard titration solution volume of sample solvent 80 mL, the volume 0.02 mL at X less than 100 ×10^-6,and the titration interval volume 0. 05 mL at X more than 100×10^-6. The detection range of X was （80 -2 000）×10^-6, and the adding standard recovery rate was 91. 1% -121.0%. The empirical formula of precision for precision limit （r） and repeatability limit （R） was r = 0. 063 X ＋ 1. 240 and R = 0. 200 X - 8. 440 respectively.