Analytical techniques and methods used for antimony speciation analysis in biological matrices

Reports of antimony speciation analysis in biological matrices are so far limited. More specifically, only inorganic antimony (V) and antimony (III), mono-, di- and tri-methylantimony species, along with four complexes of Sb-V with lactate and citrate ligands, and two complexes of Sb-III with glutathione have been so far identified. The limited progress may partly be attributed to the lack of suitable analytical methodologies. The main problems and challenges faced are (1) to achieve quantitative Sb extraction from solid biological materials, (2) species instability and their preservation during sample processing and analysis, (3) low chromatographic recovery of Sb from chromatographic columns with increased potential for species conversion when using stronger eluting mobile phases, and (4) trace level Sb species present at too low concentrations for molecular mass spectrometric identification. In the present article the hitherto used analytical methods and techniques are reviewed, with emphasis on identifying their main limitations, as well as highlighting recent breakthroughs. Re-assessing some of our current practises seems appropriate if we want to further advance the Sb speciation field, especially concerning the identification of Sb-complexes. Because of the generally low extractability, future antimony speciation studies may have to also rely on solid state analytical methods. In the case of sufficient extractability further advances in new separation methods are urgently required in order to achieve high column recoveries and maintain intact Sb species for further detection.