CHAPTER 14 • Occurrence, Formation and Fate of Organoantimony Compounds
teresting results were found in the estuary and bay samples. The Ochlockonee Bay
Estuary was tested along the salinity gradient, and the concentration of MSA increased
with increasing salinity. At the lowest salinity (4.3%) MSA concentration was 0.8 ngl'Sb with no DMSA detected. DMSA was detected when salinity reached 23.8% and in
subsequent samples at 30.2 and 33.4% salinity at 1.1 and 1.5 ngl-'Sb respectively. The
highest detected levels of MSA were also in these samples (10.9 and 12.6 ngt'Sb). The
Gulf of Mexico, Apalachee Bay was the only other location where DMSA was detected;
the samples contained the highest detected level of DMSA at 3.2 ngt'Sb, while only
5.3 ngl-'Sb as MSA was detected.
Further reports from this group confirmed the presence of methylantimony species in disparate marine locations. Polluted estuarine water from Portugal and sea water
from the Baltic were analysed and found to contain low levels of methylantimony species (Andreae et al. 1983; Andreae and Froelich 1984). Since these reports, the nature
of the standard compounds used to identify MSA and DMSA has been questioned and
further attempts to synthesize these compounds have been unsuccessful (Dodd et al.
1992). The ability of these compounds to form in nature has therefore been questioned.
Nevertheless, the reports of Andreae et al. did constitute the first knowledge of
methylantimony compounds found in the environment and the existence of an antimony carbon linkage is not in question. The molecular structure of the compounds
remains unresolved; MSA and DMSA were not necessarily the actual methylantimony
species present in the environments tested. A further report of organoantimony compounds in the environment came from a group in Germany investigating the production of volatile metalloid species from sewage and landfill gases (Hirner et al. 1994;
Feldmann and Hirner 1995). Trimethylantimony was found in these emissions along
with many other organometallic species: the anoxic nature of these environments allowed this species to be detected where it would normally oxidize to antimony(V)
species in an oxic environment. Dodd et al. (1996) have recently reported organometallic antimony compounds in pond weed (Potamogeton pectinatus) extracts from a
polluted region in Canada. The method used was hydride generation coupled with gas
chromatography-mass spectrometry (GC-MS). Trimethylantimony, dimethylantimony
hydride and methylantimony dihydride were all identified in this sample. There
was no study of the inorganic components. This work, however, does confirm that all
three antimony carbon linkages can survive the oxidation process and that methylantimony species exist in the natural environment. Total antimony concentration in
the pond weed was 48 flg g-l; quantification of the methylantimony species was not
reported.
That there are few reports of organoantimony species in the environment may be
due to the low crustal abundance of the element in relation to detection limits of available analysis methods. Detection limits of analytical systems generally are falling,
which will undoubtedly increase the reports of organometallic antimony species in
the environment. Another factor influencing the number of reports is that few groups
so far have studied antimony chemistry in the environment. Increasing emissions and
uses of antimony may increase concentrations of this material, which will lead to further study of antimony and its compounds. This is likely to enhance our understanding of environmental antimony chemistry generally. Very recently methylantimony
compounds have been found in biota associated with an antimony-rich terrestrial
region (Craig et al. 1999).
teresting results were found in the estuary and bay samples. The Ochlockonee Bay
Estuary was tested along the salinity gradient, and the concentration of MSA increased
with increasing salinity. At the lowest salinity (4.3%) MSA concentration was 0.8 ngl'Sb with no DMSA detected. DMSA was detected when salinity reached 23.8% and in
subsequent samples at 30.2 and 33.4% salinity at 1.1 and 1.5 ngl-'Sb respectively. The
highest detected levels of MSA were also in these samples (10.9 and 12.6 ngt'Sb). The
Gulf of Mexico, Apalachee Bay was the only other location where DMSA was detected;
the samples contained the highest detected level of DMSA at 3.2 ngt'Sb, while only
5.3 ngl-'Sb as MSA was detected.
Further reports from this group confirmed the presence of methylantimony species in disparate marine locations. Polluted estuarine water from Portugal and sea water
from the Baltic were analysed and found to contain low levels of methylantimony species (Andreae et al. 1983; Andreae and Froelich 1984). Since these reports, the nature
of the standard compounds used to identify MSA and DMSA has been questioned and
further attempts to synthesize these compounds have been unsuccessful (Dodd et al.
1992). The ability of these compounds to form in nature has therefore been questioned.
Nevertheless, the reports of Andreae et al. did constitute the first knowledge of
methylantimony compounds found in the environment and the existence of an antimony carbon linkage is not in question. The molecular structure of the compounds
remains unresolved; MSA and DMSA were not necessarily the actual methylantimony
species present in the environments tested. A further report of organoantimony compounds in the environment came from a group in Germany investigating the production of volatile metalloid species from sewage and landfill gases (Hirner et al. 1994;
Feldmann and Hirner 1995). Trimethylantimony was found in these emissions along
with many other organometallic species: the anoxic nature of these environments allowed this species to be detected where it would normally oxidize to antimony(V)
species in an oxic environment. Dodd et al. (1996) have recently reported organometallic antimony compounds in pond weed (Potamogeton pectinatus) extracts from a
polluted region in Canada. The method used was hydride generation coupled with gas
chromatography-mass spectrometry (GC-MS). Trimethylantimony, dimethylantimony
hydride and methylantimony dihydride were all identified in this sample. There
was no study of the inorganic components. This work, however, does confirm that all
three antimony carbon linkages can survive the oxidation process and that methylantimony species exist in the natural environment. Total antimony concentration in
the pond weed was 48 flg g-l; quantification of the methylantimony species was not
reported.
That there are few reports of organoantimony species in the environment may be
due to the low crustal abundance of the element in relation to detection limits of available analysis methods. Detection limits of analytical systems generally are falling,
which will undoubtedly increase the reports of organometallic antimony species in
the environment. Another factor influencing the number of reports is that few groups
so far have studied antimony chemistry in the environment. Increasing emissions and
uses of antimony may increase concentrations of this material, which will lead to further study of antimony and its compounds. This is likely to enhance our understanding of environmental antimony chemistry generally. Very recently methylantimony
compounds have been found in biota associated with an antimony-rich terrestrial
region (Craig et al. 1999).