Antimony speciation by inductively coupled plasma mass spectrometry using solid phase extraction cartridges

Abstract

A novel and simple method for inorganic antimony speciation is described based on selective solid phase extraction (SPE) separation of antimony(III) and highly sensitive inductively coupled plasma mass spectrometric (ICP-MS) detection of total antimony and antimony(V) in the aqueous phase of the sample. Non-polar SPE cartridges, such as the Isolute® silica-based octyl (C₈) sorbent-containing cartridge, selectively retained the Sb(III) complex with ammonium pyrrolidine dithiocarbamate (APDC), while the uncomplexed Sb(V) remained as a free species in the solution and passed through the cartridge. The Sb(III) concentration was calculated as the difference between total antimony and Sb(V) concentrations. The detection limit was 1 ng L⁻¹ antimony. Factors affecting the separation and detection of antimony species were investigated. Acidification of samples led to partial or complete retention of Sb(V) on C₈ cartridge. Foreign ions tending to complex with Sb(III) or APDC did not interfere with the retention behavior of the Sb(III)–APDC complex. This method has been successfully applied to antimony speciation of various types of water samples.