Electrophoresis is based on the difference of molecular weight and charge of the separated substance. During electrophoresis, those with large molecular weight move slowly and those with small molecular weight move fast, so after electrophoresis for a period of time, those with large molecular weight are behind.

For chromatographic columns, the landlord should refer to gel filtration (there are many kinds of chromatographic columns, such as ion exchange chromatography and affinity chromatography, and the separation principle is different), which is based on the size of the separated substance. To put it simply, the substances filled in the gel filtration contain many pores. Among the substances to be separated, the substances with large molecular weight do not enter the pores, but the small substances enter these pores directly with the eluent, and naturally, when the eluent is eluted, it will flow out later.