Quantitative Elemental Speciation: Challenges and Strategies Based on Multi-Labelled Multi-Species Isotope Dilution ICP-MS

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Abstract According to IUPAC, a chemical species is defined as “the specific form of an element defined as to isotope composition, electronic oxidation state and/or complex or molecular structure^[1]. To carry out chemical speciation, new speciation analysis techniques and strategies are needed. Probably the most popular and useful techniques for speciation analysis are hybrid techniques where a powerful separation is coupled (preferable “on-line”) to an element-specific detector. In fact, the whole strategy for speciation analysis involves a considerable number of discrete steps. These include usually: solid-liquid extraction (if the sample is solid), preconcentration, derivatization, separation of derivatized analytes (e.g. chromatography) and final specific detection (e.g. “on-line” ICP-MS). It is well known that important errors can occur at any of those individual speciation steps. First, solid-liquid extractions should preserve the molecular form (species) of the analytes. Second, preconcentration, derivatization, separation and detection speciation methods should be fully investigated and understood in order to obtain accurate (reliable) determinations of the sought species.From all the above, it is clear that validation of quantitative speciation results is urgently needed. A powerful approach for analytical validation is the use of isotope dilution analysis (IDA). Therefore the application of “speciated” IDA (SIDA) techniques for validation of results for mono-, di-, and tributyltin (MBT, DBT and TBT, respectively) in sediments^[2] and seawater samples^[3] will be discussed using a multi-species spike enriched with ¹¹⁹Sn and final measurement by a hybrid GC-ICP-MS technique. Similarly, the synthesis of multi-labelled multi-species spikes will be described. The application of “doubly- and triply-labelled spikes” has allowed the evaluation of the extent of possible decomposition reactions (the corresponding decomposition factors can be quantified) during several solid-liquid extraction procedures under different conditions. Results on application of a double spike approach (which can correct for the stepwise degradation of TBT) to validate common extraction procedures (e.g. mechanical shaking, ultrasonic leaching, microwave assisted and accelerated solvent extraction) for the determination of butyltin species in sediments^{[4, 5]} will be discussed in detail. Finally, a new triple spike methodology (which can correct not only for the stepwise degradation of TBT but also for other alternative degradation routes) as well as the application of this innovative tool to the analysis of biota (such as mussel tissue) or human samples (urine and blood) will be presented. References

Received: 2003-04-20 Accepted: 2003-06-10

Cite this article:

Alfredo SANZ-MEDEL,Pablo RODR(I)GUEZ-GONZ(A)LEZ,Jorge RUIZ ENCINAR, et al. Quantitative Elemental Speciation: Challenges and Strategies Based on Multi-Labelled Multi-Species Isotope Dilution ICP-MS[J]. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2004, 24(02): 255-255.

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http://www.gpxygpfx.com/EN/Y2004/V24/I02/255