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 lmowledge, 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 perch/orate anion. The transition of 35Cl]604- （m/z 98.9） into 3SC11603 （m[z 82.9） was monitored for quantifying the main analyte, and the transition of 37C11604 （m/z 100.9） into 37C1~603- （m]z 84.9） was monitored for examining a proper isotopic abundance ratio of 3sCl to 37C1, 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 oerchlorate, ran^in~ from 10 nell to 340 nell..
