Methods for depositing a stationary phase in a tube for chromatography. The resulting column may be a variable gradient column or a standard open tubular column with a uniform thickness stationary phase. The methods include providing a tube comprising an electrically conductive interior surface and having a composition within the tube, the composition comprising a stationary phase precursor and at least one of an electrolyte and a reactant precursor, and electrochemically reacting the reactant precursor or the stationary phase precursor to form a stationary phase in the tube.