无苯溶剂-等量电位滴定法测定油品中碱性氮化物含量

Determination of base nitrogen content in oils by equal-increment-potentiometric titration with benzene-free solvent

以乙酸-丙酸混合物（二者体积比为1∶3）为高氯酸滴定剂溶剂,石油醚-乙酸混合物（二者体积比为1∶1）为样品溶剂,同时采用两步溶解方式,运用等量电位滴定法测定油品中的碱性氮化物含量.结果表明,新溶剂配方的0.02 mol/L高氯酸滴定液,在凝固点下降同时,标定终点清晰,稳定性良好;以原油为基体,蜡油为标准物,通过回收率实验进行了方法准确度测定,回收率为98.6％～103.0％,表明该方法的准确度高;无论是浅色油品还是深色油品,最大相对标准偏差为1.83％,实际样品的5次测定结果的最大差值仅为允许差值（SH/T 0162标准规定的重复性指标）的25％～100％.

The content of basic nitrogen in oil was determined with the mixture of acetic acid and pro- pionic acid（volume ratio 1：3） as the solvent of per- chloric acid titrant, the mixture of petroleum ether and acetic acid （ volume ratio 1：1 ） as the solvent of sample oil by the equal- increment- potentiometric titration method with two - step solution mode. The results showed that the terminal point was clearly demarcated, its stability was better, the condensation point of titrant was decreased when 0.02 mol/L per- chloric acid solution in new mixed solvent was used. The recovery rate of addition standard was in therange of 98.6% -103.0% with crude oil as matrix and wax oil as standard substance. No matter wheth- er the sample oil was light or dark, the relative standard deviation was 1.83% ,indicating this meth- od had high accuracy. The maximum differences of 5 repeated determination results of the actual sam- pies were only 25% - 100% of the tolerance in SH/ T 0162 standard.