Environmental Engineering Reference
In-Depth Information
sensitivity of the general detector for the organotin levels found in nature.
Even though in the last years with the utilization of MS [ICP-MS in particular
(with or without ID), but also MS
MS and ESI-TOF-MS] [51, 64]
and fluorimetry (after post-column derivatization) [56] as instrumental de-
tection techniques, LC methods satisfy the requirements of selectivity and
sensitivity for the determination of organotin compounds in environmental
samples [69], and are more largely applied.
/
MS, ESI-MS
/
4
Conclusions
Notwithstanding the ban of TBT in antifouling paints, TBT can still be en-
countered in the marine environment, because of its slow degradation and
high sorption to suspended matter and sediment and high tendency to be
bioaccumulated in marine organisms.
Its determination involves the use of multistep speciation analysis methods
including extraction, derivatization, clean up, preconcentration, separation
and detection. In some cases, some steps are simultaneously applied such as
extraction
preconcentration or even avoided such as derivati-
zation in the case where high performance liquid chromatography is applied.
Each step presents specific problems that can be faced with different ap-
proaches presenting both advantages and disadvantages.
/
derivatization
/
Extraction
In the case of water samples, the applied extractants can be solvents or solid
phases. The efficiency of LLE mainly depends on the type of chosen extrac-
tant(s) and on the experimental parameters such as pH, sample to solvent ratio
and extraction time. The main advantages of using LLE are the high efficiency,
reproducibility in recovery and high enrichment factors. However, its disad-
vantages are the high cost, laborious handling and the difficulties of adapting
them to field analysis and the potential hazard of organic solvents to the oper-
ators' health. The efficiency of SPE depends on the type of adsorbent chosen
(both in terms of adsorption capacity and breakthrough) and on experimental
conditions such as pH and sample flow rate. It presents a number of advantages
over LLE as it is easy to handle, adaptable to field analysis, the extracts can
be more easily stored and transported, it is of lower cost, allows high routine
and presents a very low potential health hazard. In addition, no additional pre-
concentration is needed when it is coupled directly to a separation
/
detection
system. However, the main disadvantages are the lower enrichment factor,
efficiency and reproducibility when compared to LLE.
Inthecaseofsolidsamples,theextractionefficiencydepends,inadd-
ition to the choice of extractant(s) and the experimental parameters, on the
