A device, method and kit for the electrophoretic separation and purification of charged and neutral compounds in an analyte solution. The device comprises a chamber (1), at least one wall of which is composed of a chemical buffering system (4). A potential difference is applied across the buffering system, resulting in the charged and neutral compounds being differentially separated by extraction of the charged compounds into the buffering system. The device also comprises means for collecting the separated compounds, preferably in ampholyte-free or buffer-free solution and optionally means for recycling the separated fractions.