A system for controlling the flow rate into a chromatographic column is disclosed generally comprising communicating a fluid to the column through a transfer line, measuring the inlet pressure, determining the outlet pressure, and adjusting the applied pressure until the inlet and outlet pressures produce a desired flow rate for the transfer line outlet. In certain embodiments, the applied pressure is adjusted by controlling a proportional valve. In some embodiments, the outlet pressure is determined by measuring the pressure drop across the transfer line and calculating the outlet pressure from the measured inlet pressure and the pressure drop.