Various metals and metalloids can be converted by a variety of microorganisms to their volatile methyl derivatives. These bioconversions are important from an environmental perspective because they take place over long time periods and the products have quite different properties (e.g., transportation, toxicological) as compared to the inorganic species from which they are derived. Whereas the biomethylation of arsenic is well established, that of the closely related element antimony is not, and there are no reports of antimony methylation by monoseptic microbial cultures. We report here, for the first time, the formation of trimethylantimony [(CH3)3Sb] by a characterized microorganism, Scopulariopsis brevicaulis, grown aerobically in the presence of inorganic antimony. Volatile antimony evolved into the headspace above the fungal cultures was quantified by remote trapping and analysis by inductively coupled plasma−mass spectrometry (ICP−MS). The existence of biogenic trimethylantimony was established, following exclusion of oxygen from cultures after growth, by remote trapping of volatile compounds and analysis by gas chromatography with compound-specific (mass spectrometry) or element-specific (atomic absorption) detec tion. No other volatile product containing antimony was detected in culture headspace gases.

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The limitations of conventional gas chromatography–mass spectrometry (GC–MS) analyses for alkyl‐ and aryl‐tin compounds are discussed, particularly the excessive fragmentation from electron impact (EI) ionization. Negative EI methods exhibit low ionization capabilities and are restricted to compounds with an electronegative centre, and are thus not suitable for general routine analysis. Liquid chromatography–MS (LC–MS) interfaces offer potential advantages in terms of reduced sample work‐up since no derivatization is required. Electrospray techniques give reproducible mass spectra for each compound studied under fixed instrumental parameters. Changes in the cone/repeller voltages can radically alter the observed mass spectra. High‐mass species were observed for each compound studied and tentative structures for these species are proposed.