基于移动中和界面(MNB)概念,研制了一种基于电泳酸碱滴定(EABT)的新装置。其核心技术是在电泳管中建立MNB,通过对电泳管中的MNB在一定时间内迁移距离的测定,推测酸或碱的浓度。EABT实验表明:HCl浓度的对数值与MNB移动距离存在线性关系。此关系可用于检测未知酸的浓度;不同酸碱指示剂对EABT方法没有明显影响,这能有效避免在容量分析法中不同指示剂对判定终点断滴所造成的误差;EABT具有良好的精密性和稳定性,日内差和日间差的RSD值分别小于1.6%和3.8%。
A novel principle,device and method of electrophoretic acid-base titration(EABT) was developed based on the concept of moving neutralization boundary(MNB).The core component of EABT device is the electrophoretic tube set above operating platform,and the movement of MNB during a certain time has direct relation with the concentration of acid or alkali.A series of experiments were conducted with the device.The results revealed(1) there was a good linearity between the moving distance of MNB and natural logarithmic concentration of HCl under the optimized conditions,and the linearity relationship could be well used to determine the concentration of acid;(2) different indicators had no obvious effect on EABT analysis,distinguishing strong influence on the judgment of equivalence-point titration in the classic volumetric analysis;(3) the RSD values of intra-day and inter-day runs were less than 1.6% and 3.8%,respectively,indicating good precision and stability.