The general flow rate of a semi-micro column (4.6mm I.D.) is 0.3mL/min. The eluent can pass through HK-404L column at a higher flow rate with the conventional HPLC instrument. Polystyrene was analyzed using a flow rate of 0.3mL/min and 1.0mL/min. When the flow rate was raised to 1.0mL/min, the molecular chains were not degraded.