SH/T0162标准中润滑油基础油碱性氮测定方法准确度探讨

Study on determination accuracy of basic nitrogen of lube oil base stoek

以润滑油基础油为测定对象,讨论了SH/T0162《石油产品中碱性氮测定法》中存在的问题。考察了取样量、空白值、试剂及光线对碱性氮测定的影响。结果表明,取样量过多指示剂呈蓝色无法进行测试;不同生产厂家的试剂空白值不同,同一厂家的试剂空白值也会随试剂批号及时间而变化;不同来源的甲基紫指示剂也会影响碱性氮测定过程中滴定终点的判断;阴天及夜间进行碱性氮测试,会使测定值偏大甚至无法进行测试。

The influencing factors exited in SH/T0162 Determination of Basic Nitrogen in Black Oils were discussed using lube base oils as the determining object. The influence of sample weight, blank value, reagent and light on the determination of basic nitrogen was investigated. The results showed that basic nitrogen can not be de- termined using excessive sample because indicator presents blue. Reagents obtained from various manufactures have different blank values, which also is different for different batch numbers products obtained in the same manufacture. Reagent blank values with the same batch change with time, so it must be determined before the sample is determined. Methyl violet indicator of different manufactures also affect the titration end of basic nitro- gen, which must be paid attention in the experiments. The determination value is bigger, even undetermined, when the experiments carried out at night or cloudy day.