Streamlining antimony speciation analysis in natural waters with frontal chromatography-ICP-MS

Antimony is a naturally occurring toxic metalloid whose cycling has been greatly affected by human activities. It is considered as a priority interest pollutant and limits have been set for its presence in e.g., drinking water. Inorganic Sb redox species include the III and V oxidation states and they exhibit different environmental behavior, bioavailability, mobility and toxicity, stimulating the development of several procedures for speciation analysis, mainly based on the hyphenation of liquid chromatography and spectrometric methods (usually ICP-MS or atomic fluorescence). Here, the development and validation of a sensitive, fast, high throughput and cost effective procedure for the selective determination of Sb(III) and Sb(V) in water samples is reported. The method is based on the separation of the two species by a short, low pressure homemade cation exchange column, thus avoiding the use of the LC instrumentation, and detection by ICP-MS for sensitive determination. A very fast analysis time of 3 min is enough to separate and detect the two species with detection limits (LOD) below 1 ng L−1 for both Sb(III) and Sb(V). The limit of linearity and possible interferences due to the presence of a large excess of one species over the other were also investigated. Validation was successfully achieved by a spike and recovery strategy on mineral water samples. The procedure was finally compared to existing ones highlighting its benefits in terms of analysis time, very low limits of detection and favorable instrumental configuration. Possible advances in terms of application to different environmental matrices were also discussed.