Alkylation

REVIEW: Yes

DATE: 2010

REF: M. Filella, Alkylantimony derivatives in the environment. METAL IONS IN LIFE SCIENCES 2010, 7, 267–301.

NUMBER OF REFERENCES IN REVIEW: 110 (references up to 2010)

NUMBER OF CITATIONS (up to 31 December 2015): 8

PREVIOUS REVIEWS? The subject has been included in previous reviews but values and conclusions should be replaced by the review above.

CONCLUSIONS (adapted from conclusions of review above):

• Methylated antimony species have been detected in various environmental compartments at very low concentrations. The number of published studies (seawaters: 7, freshwaters: 2, soils: 4, sediments: 2, biota: 6) is fairly low as compared to other elements.
• Monomethyl (MMA), dimethyl (DMA), and trimethyl (TMA) species have been reported to exist in the various systems, but these results, along with those from laboratory incubations, are suspected of artefacts during analysis, in particular when HG techniques –by far the most commonly applied– are used. Alternative methods, such as HPLC-based methodologies, have not yet been extensively used and, curiously, where they have been applied –always using a TMA standard– the only species detected has been TMA. When MSA (methylstibonic acid) and DMSA (dimethylstibinic acid ) standards were used in seawater studies, only MMA and DMA were found. The fact that the results obtained are so dependent on the techniques and standards used merit further investigation.
• More data, obtained in a larger variety of environmental systems, and as free as possible from analytical uncertainties, are needed in order to ascertain the importance of methylated compounds in the biogeochemical cycle of antimony.
• There is scant information about the properties and reactivity of alkylantimony species, and even less in conditions close to environmental ones. Data on physical and chemical properties of these compounds are fragmentary and old. Moreover, ‘pure chemists’ are used to working either with pure compounds or at concentration levels in solution which are much higher than the low concentrations found in natural systems, while in fact reactivity may be strongly dependent on concentration.
• Nothing is known about the binding of methylated antimony by natural ligands, whether those with low molecular mass or colloidal ones (e.g., natural organic matter, clays, iron oxyhydroxides, etc).
• Further work is needed to reconcile puzzling facts such as the constant concentrations of methylantimony species found in surface oceanic waters and the low yields of antimony biomethylation obtained in laboratory studies performed under conditions that should, in principle, favour that process.

PAPERS PUBLISHED AFTER REVIEW OR MISSED: Müller et al., 2009; Diaz-Bone and Van de Wiele, 2010; Duester et al., 2011; Hernández-Nataren 2011; Quiroz et al., 2011; Ge and Wei, 2012; Yang et al., 2015.

REVIEW CITED IN PAPERS AFTER REVIEW? Never.

COMMENTS: slow pace of publication, subject apparently of low interest now.