The isoelectric point (IEP) is the pH value where the zeta potential is zero.can be determined by the Nicomp 380 ZLS by titrating the sample and recording zeta potential as a function of pH. 
等電點可以通過滴定樣品PH值，再用Nicomp 380 ZLS 記錄Zeta電位，Zeta電位為0時的PH值就是等電點。