204 Organic compounds in soils, sediments & sludges
The method is applicable to non-saline and saline sediments. Other forms of
organic or inorganic lead do not interfere. The detection limits for sediment (5 g sample) is 0.01 mg kg
−1 . Recoveries from sediments ranged from 94% for triethyllead
to 111% for trimethyllead in the range 1–20 µg alkyllead spiked to 1 g of sediment.
An average standard deviation of 4% for trimethyllead and triethyllead and 15% for
dialkylead compounds were obtained.
In this method EDTA is added to the sediment and a hexane extract examined by
gas chromatography.
9.3 ORGANOTIN COMPOUNDS
Butyl and cyclohexyl tin compounds have been found in river and lake sediments.
These probably originate from the use of organotin antifoulants on boats and pier
works.
Typical levels are depicted below:
BuSn
3+
0.055 mg kg
−1
BuSn
2+
0.14 mg kg
−1
BuSn
+
0.28 mg kg
−1
Cyclohexyl 2 Sn
2+
0.01 mg kg
−1
Cyclohenyl 3 Sn
+
0.075 mg kg
−1
The sorption of tributyltin on estuarine sediments under various conditions of
alkalinity has been studied by Unger et al [9]. The resulting estimated equilibrium
sorption coefficients were in general agreement with apparent sorption coefficients
calculated from concentrations of tributyltin in water and sediment at various sites
in Chesapeake Bay. However, very high apparent sorption coefficients were found in
areas where there was high boating activity; this could be due to the presence of tributyltin paint chips in the sediment. Sorption and desorption coefficients were similar,
indicating that sorption of tributyltin was reversible. Desorption kinetics indicated
initial rapid desorption followed by desorption at a slower rate.
The determination of organotin compounds in bottom sediments is a complex
process that requires a number of analytical steps i.e. sample collection, transport
and storage; extraction of analytes from sediment; derivatisation; extract purification;
enrichment; and the final chromatographic measurement. Stanbrusska et al [10] carried out a detailed study of the whole process. It is time and labour consuming and
subject to securing representative sample. In this review the most frequently encountered problems and the examples of possible analytical solutions are discussed, which
encompass the specific steps of speciation analysis of these toxic compounds.
Organotin compounds occur in the marine environment in various chemical forms
which may affect live organisms in different ways, for example, toxicity, persistence
or bioavailability effect. In such cases, it is therefore more critical to determine the
content of a specific species (e.g., the most toxic one) than a measurement of the total
content of all physicochemical forms present in a given environment solution.
Isolation of butyltin and phenyltin derivatives from the ‘primary matrix’sediments-and transferring them into a ‘secondary matrix’ for example an appropriate
solvent such as methanol is necessary because of the other analytical steps such as
derivatisation.
The method is applicable to non-saline and saline sediments. Other forms of
organic or inorganic lead do not interfere. The detection limits for sediment (5 g sample) is 0.01 mg kg
−1 . Recoveries from sediments ranged from 94% for triethyllead
to 111% for trimethyllead in the range 1–20 µg alkyllead spiked to 1 g of sediment.
An average standard deviation of 4% for trimethyllead and triethyllead and 15% for
dialkylead compounds were obtained.
In this method EDTA is added to the sediment and a hexane extract examined by
gas chromatography.
9.3 ORGANOTIN COMPOUNDS
Butyl and cyclohexyl tin compounds have been found in river and lake sediments.
These probably originate from the use of organotin antifoulants on boats and pier
works.
Typical levels are depicted below:
BuSn
3+
0.055 mg kg
−1
BuSn
2+
0.14 mg kg
−1
BuSn
+
0.28 mg kg
−1
Cyclohexyl 2 Sn
2+
0.01 mg kg
−1
Cyclohenyl 3 Sn
+
0.075 mg kg
−1
The sorption of tributyltin on estuarine sediments under various conditions of
alkalinity has been studied by Unger et al [9]. The resulting estimated equilibrium
sorption coefficients were in general agreement with apparent sorption coefficients
calculated from concentrations of tributyltin in water and sediment at various sites
in Chesapeake Bay. However, very high apparent sorption coefficients were found in
areas where there was high boating activity; this could be due to the presence of tributyltin paint chips in the sediment. Sorption and desorption coefficients were similar,
indicating that sorption of tributyltin was reversible. Desorption kinetics indicated
initial rapid desorption followed by desorption at a slower rate.
The determination of organotin compounds in bottom sediments is a complex
process that requires a number of analytical steps i.e. sample collection, transport
and storage; extraction of analytes from sediment; derivatisation; extract purification;
enrichment; and the final chromatographic measurement. Stanbrusska et al [10] carried out a detailed study of the whole process. It is time and labour consuming and
subject to securing representative sample. In this review the most frequently encountered problems and the examples of possible analytical solutions are discussed, which
encompass the specific steps of speciation analysis of these toxic compounds.
Organotin compounds occur in the marine environment in various chemical forms
which may affect live organisms in different ways, for example, toxicity, persistence
or bioavailability effect. In such cases, it is therefore more critical to determine the
content of a specific species (e.g., the most toxic one) than a measurement of the total
content of all physicochemical forms present in a given environment solution.
Isolation of butyltin and phenyltin derivatives from the ‘primary matrix’sediments-and transferring them into a ‘secondary matrix’ for example an appropriate
solvent such as methanol is necessary because of the other analytical steps such as
derivatisation.