Perchlorate is a wide-spread contaminant in drinking water. In addition to a few natural sources, perchlorate is generally released into drinking water from propellants and from disinfecting and bleaching agents. Convenient separation from other ions is accomplished on a column of the Metrosep A Supp 7 - 250/4.0 type before it is quantified using sequential suppression and conductivity detection. In comparison to AN-S-324, this Application Note shows a considerably lower matrix influence.