Comparison of on-line coupling of ion-chromatography with atmospheric pressure ionization mass spectrometry and with inductively coupled plasma mass spectrometry as tools for the ultra-trace analysis of bromate in surface water samples

Ion chromatography in combination with atmospheric pressure ionization mass spectrometry (API-MS) as well as with inductively coupled plasma mass spectrometry (ICP-MS) had been compared for trace analysis of bromate. The results indicate that both techniques yield comparable results, which are in excellent agreement with standard methods for bromate determination. Furthermore, both techniques showed almost equal absolute detection limits (approximately 50 pg bromate injected). Contrary to IC–API-MS, IC–ICP-MS can tolerate a higher salt concentration in the mobile phase. This allows the use of high-capacity columns combined with large sample volumes. This lowered the concentration based detection limits by one order of magnitude for IC–ICP-MS compared to IC–API-MS (0.06 μg/l vs. 0.5 μg/l). On the other hand, IC–API-MS is able to allow a positive identification of bromate even in cases when IC does not fully separate bromate from other bromine-containing species. The performance data of both IC–MS techniques have been established by participation in an international round robin test.