Abstract: According to the electric poential distribution of a non-uniform field in a sample solution, a the-oretical model of the non-uniform electric field, namely, a pair Of equal and opposite charges separatedfrom each other in a distance, was used to investigate the non-uniform field electrostacking.The effect ofthe non-uniform field on electrostacking was presented in this paper.In order to validate the theoreticalmodel, anionic chromium(Ⅵ ) and cationic lead (Ⅱ ) in mineral water were pre-concentrated with an im-proved non-uniform field electrostacking system simultaneously.And the experimental results were coinci-dent with the theoretical prediction.

Key words: Non-uniform electric field, Electrostacking, Pre-concentration