This study investigated reusability of costly guard column by ultrasonic. It also investigated various effects that affect to guard column generation by ultrasonic. When investigated 30 KHz of frequency, area of ascorbic acid is 73.0% compared to unused guard column. As a result of investigation of effect of pH, guard column by ultrasonic is effective at alkali area. As a result of investigation of solvent effect, when ethanol is used, generation rate is 81.9% as of peak area compared to the case of analysis in un used column. From the result, it indicates that regenerated guard by ultrasonic is reusable.

• Byung-Dae Lee Corresponding author