Asahipak GF-310 HQ (an Aqueous/Organic (multi-solvent use) SEC column) was used to analyze a cationic surfactant, benzalkonium chloride. Two mobile phase salts, 50 mM sodium chloride and 50 mM sodium nitrate, mixed with ACN were tested. Both solvents provided good analytical performances by suppressing ionic interactions. It should be noted that the sodium nitrate has UV absorbance, thus if UV detector was used, the background level will become high. This may result in lower sensitivity compared to using sodium chloride as a salt.