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New methodologies have been developed for the determination of organotin and
organolead compounds in environmental samples.
Several high performance liquid chromatographic separations of organotin compounds
have been tested and the best system (cation-exchange chromatography with methanol and a
citrate buffer) employed for the determination of tributyltin (TBT), triphenyltin (TPhT),
dibutyltin (DBT) and monobutyltin (MBT) in environmental samples. The coupling between
high performance liquid chromatography (HPLQ and the inductively coupled plasma-mass
spectrometer (ICP-MS) for this application has been modified to yield limits of detection of
0.44,0.26,1.4 and 0.23 ng. g-' as Sri for TBT, TPhT, DBT and MBT respectively. Different
extraction procedures have been tested for the determination of organotin species in samples of
environmental interest, such as sediments and biological materials. The values obtained for
TBT, TPhT and DBT in the analysis of a mussel candidate reference material, CRM 477, have
been incorporated in the certification campaign of this material.
A liquid chromatographic separation for trimethyllead (TML) and triethyllead (TEL) has
also been developed. Artificial rain water has been analysed for TML. The system proved to
be valid for the determination of TML in this sample, even in the presence of high amounts of
inorganic lead.
Finally, isotope dilution analysis (IDA) was incorporated in the method. Tributyltin
iodide (TBTI) and trimethyllead chloride (TMLCI), isotopically enriched in "Sn and "Pb,
respectively, were synthesised. The mussel tissue CRM 477 was analysed with IDA-HPLC-ICPMS
for TBT. As for the analysis without isotope dilution, the result obtained was incorporated
in the certification campaign. The analysis with this methodology gave a better precision in the
overall determination than external calibration analysis. Artificial rain water, at two different
concentration levels, was analysed for TML with IDA-HPLC-ICP-MS. Better precision and
accuracy was obtained for the analysis of this material with this method than when external
calibration procedures were employed.
IDA-HPLC-ICP-MS has proved to be a valid technique for the analysis of
environmental samples. The technique simplifies the procedure, compensates for different
sources of variability and, thus, the overall precision obtained in the analysis is improved
compared to other calibration techniques. |
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