Environmental Engineering Reference
In-Depth Information
performance was obtained also by Martinez-Vidal et al. [22], who extracted
sediment samples only with toluene in the presence of DDTC as the com-
plexing agent in an ultrasonic bath, achieving recoveries of organotin species
from spiked samples ranging between 96-108%.
The application of preconcentration methods is necessary to further in-
crease the detection limit of analytical methods. Solid phase microextrac-
tion [12, 29, 31, 34, 36, 39, 49], mostly utilized after polar solvent extraction in
acidic media, is becoming very popular also for tin speciation. The cryogenic
trapping of a continuously stirred suspension of sediment and water [23]
purged with He flow directly connected with a GC-ICP-MS system has also
proved to have a good potential for the analysis of samples with very low
organotin levels. For methyltin species, Gomez-Ariza et al. [50] utilized the
advantages of the pervaporation module as a preconcentration that allows
the direct determination of the species without preliminary treatment. After
preconcentration, the species to be determined were ethylated, separated
and determined by GC-PFPD. Recovery values in the range of 90-98%were
achieved for the mono-, di- and also the trimethylated forms with this ex-
tremely simple and easily automatizable method.
In the sample preparation of sediment samples for tin speciation, the main
developments within the last years concerned the extraction and precon-
centration steps. With the application of alternative energies —microwaves,
high pressure, ultrasounds—the efficiency of the extraction step has been
increased and the required treatment time has been decreased, whereas the
application of SPME has mainly improved the preconcentration step. On the
other hand, the derivatization step has continued to be carried out essentially
with the techniques developed twenty years ago. Furthermore, the possibility
of using isotope dilution techniques for tracing possible degradation and in-
terconversion of organotin compounds during sample treatment has become
more accessible to a larger number of laboratories.
A summary of the most applied extractants, derivatizing reagents, pre-
concentration systems and instrumental techniques in the determination of
organotin compounds in marine sediment, derived from the literature pub-
lished after 2000, is reported in Table 2.
2.3
Sample Preparation Methods
for the Determination of Organotin Compounds in Biological Samples
TBT present in the marine environment accumulates through the marine
food chain, resulting in the occurrence of this compound as well as its break-
down products in marine biota organisms. Due to their lipophilic characteris-
tics, organotin compounds may be incorporated in parts of organisms where
lipids are present in a higher quantity such as the entrails, gonads and gills.
These biological tissues offer the advantage of being highly soluble in polar
