Methods for depositing a stationary phase in a tube for chromatography, in particular, as a variable gradient column are disclosed. The methods include providing a tube, loading the tube with a concentration gradient of a stationary phase precursor along its length, and removing the solvent such that the stationary phase precursor is deposited within the tube as a stationary phase to form a chromatography column. The concentration gradient is formed by combining at least a first fluid and a second fluid, with the first fluid containing the stationary phase precursor in a solvent.