Investigation on stability and preservation of antimonite in iron rich water samples

• The fast oxidation of antimonite is demonstrated when Fe2+ is in the water samples.
• We tested different agents to preserve both inorganic redox species of antimony.
• An easy to handle and effective procedure is suggested for species preservation.

The stability of antimonite in iron rich water samples is rather poor. The aim of the study was to find a simple procedure by using preservation agents to keep the speciation information from sampling till analysis. Species analysis of antimony traces (lower μg L−1 range) was done by HPLC–ICP-MS. Phosphoric acid, tartrate, and EDTA were tested as preservation agents in comparison to no addition. The use of EDTA as the preservation agent provided the best results. The suggested procedure is to add 20 mM EDTA as final concentration immediately during sampling and store them at dark and cool (6 °C) as usual. Using this procedure, the stability of Sb(III) as well as of Sb(V) was proven for at least 7 days, even for high iron concentrations.

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