Perchlorate Quantitation in Drinking Water Using Suppressed Anion Chromatography Coupled with Single Quadrupole MS

The EPA has established a Lifetime Drinking Water Health Advisory of 15 ppb for perchlorate to reduce health risks. More than 10 states in U.S. have established heath advisory levels for perchlorate in drinking water ranging from 1 to 18 ppb; for example, California and Maryland have proposed standards of 6 ppb and 1 ppb, respectively. A few quantitative methods for perchlorate have been developed by the U.S. EPA. Method 332.0 is one of the most sensitive methods using suppressed anion chromatography coupled with mass spectrometry.

In this study, an IC-MS method was developed using a novel electrolytically regenerated anion suppressor as a part of a modular IC system coupled with a LC-MS 2020 single quadrupole MS to achieve higher sensitivity and selectivity for perchlorate determination in drinking water. Both conductivity detection (CDD) and MS with electrospray ionization are used in the method. The CDD is used to monitor the column effluent, only the perchlorate fraction is directed to MS via a divert valve. Two predominant perchlorate ions are 35Cl16O4- and 37Cl16O4- with m/z are 99 and 101, respectively. Selected ion monitoring (SIM) of both ions was used in the method.