Determination of trace level of perchlorate in Antarctic snow and ice by ion chromatography coupled with tandem mass spectrometry using an automated sample on-line preconcentration method

Abstract

A new ion chromatography coupled with tandem mass spectrometry (IC-ESI-MS/MS) method, with automated sampling and on-line preconcentration, has been developed for the determination of perchlorate in Antarctic snow and ice at low part-per-trillion (ng/L) levels. To the best of our knowledge, this is the first time that an analytical method is used for the determination of perchlorate in Antarctic snow and ice. The IC-ESI-MS/MS instrumentation consisted of an ICS2000 ion chromatography (IC) system coupled to an API3200 electrospray tandem mass spectrometer (ESI-MS/MS). On-line preconcentration was realized through a six-port injector valve, a TAC-ULP1 concentrator column and an AS auto-sampler. Multiple reaction monitoring (MRM) mode was used to quantify the perchlorate anion. The transition of 35Cl16O4− (m/z 98.9) into 35Cl16O3− (m/z 82.9) was monitored for quantifying the main analyte, and the transition of 37Cl16O4− (m/z 100.9) into 37Cl16O3− (m/z 84.9) was monitored for examining a proper isotopic abundance ratio of 35Cl to 37Cl, which was used as a confirmation tool. The limit of detection (LOD) and limit of quantitation (LOQ) for the method was 0.2 ng/L and 0.5 ng/L, respectively. And this new method exhibited acceptable accuracy and precision for samples at ng/L levels. All the tested snow and ice samples were found to contain measurable amount of perchlorate, ranging from 10 ng/L to 340 ng/L.