Environmental Engineering Reference
In-Depth Information
nard reagents (potentially leading to degradation or volatilization), the neces-
sity of destroying the excess reagent carefully (thereby increasing the number
of steps) and the high time consumption. Contrary to the other two hy-
dridization and alkylation methods, Grignard derivatization is particularly
suitable for solid samples and less so for water samples.
No significant improvements have been experienced recently in the deriva-
tization of organotin compounds. The techniques and their application have
been essentially the same for more than 15 years.
Preconcentration
Recently, several preconcentration techniques have been applied in specia-
tion analysis which include biotrapping (for inorganic species), flow injection,
purge and trap, cryogenic trapping and SPME. SPME—and to a smaller extent
even cryogenic trapping—has been successfully applied to organotin analysis.
It is easy to handle, not invasive which is crucial for preserving the original
speciation equilibrium, allows a reduced number of steps and the simultaneous
extraction
preconcentration of species of different elements and, furthermore,
it is a free-of-solvent technique thus with reduced health hazard for operators.
The main disadvantage is certainly its scarce reproducibility that still represents
the major drawback in the diffusion of this technique.
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Instrumental Analysis
The mostly applied instrumental techniques for the routine determination of
organotin compounds in environmental samples are certainly GC-FPD and
GC-MS. Recently, an increase has been noted in the use of ICP-MS as the
detector for tin speciation coupled either with GC and, mainly, HPLC.
The most significant development in this field is the application of isotope
dilution techniques. This is worth stressing not so much for the improvement
of determination performances, but above all for their potential in sample
treatment optimization. In fact, the transformation
degradation of organo-
tins species during the sample preparation steps are monitored more and
more often by the utilization of species-specific isotope-dilution, which pre-
sumably will become the most powerful tool for optimizing and validating
extraction methods in the near future.
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References
1. de Mora SJ (1996) Tributyltin: case study of an environmental contaminant. Cam-
bridge environmental chemistry series 8. Cambridge University Press, Cambridge
2. Chiavarini S, Cremisini C, Morabito R (1996) In: Caroli S (ed) Elemental Speciation
in Bioinorganic Chemistry. Wiley, New York, p 287
