Tessier extraction scheme

Single and sequential extraction schemes have been designed in earlier years and widely used to assess the different retention/release of metals in soil and sediment samples (Tessier et al., 1979 Salomons and Forstner, 1980 Thomas et al., 1980 Meguellati et al., 1987). However, the lack of uniformity in the different procedures used did not allow the results to be compared worldwide or the procedures to be... 

Table 11.2 Results of chemical equilibrium modelling of the contribution of ferrous iron phases to the proportion of iron (in %) extracted from an anoxic freshwater sediment from the Elbe River near Hamburg (Germany) by the first two acetate buffer steps of a modified Tessier sequential extraction scheme...

Ginepro, M., Gulmini, M., Ostacoli, G. and Zelano, V (1996) Microwave desorption treatment after the oxidation step in Tessier s sequential extraction scheme. Int.J. Anal. 

Perez-Cid, B., Lavilla, I., Bendicho, C. Comparison between conventional and ultrasound accelerated Tessier sequential extraction schemes for metal fractionationin sewage sludge. Fresenius J. Anal. Chem. 363, 667-672 (1999)... 

Figure 2.7 Variation in the saltmarsh sediment concentration of zinc with depth in four fractions, defined according to the sequential extraction scheme of Tessier, Campbell Bisson (1979) as F2, carbonate F3, Fe and Mn oxide and hydroxide F4, organic F5, residual. The location of the profile is Tites Point, Severn Estuary, UK.

It should be noted that the results obtained by the use of different SEPs are often diffieult to eonipare. For example, fraction-specific concentrations, percentages, and relative recoveries for Cu, Pb, and Zn in SRM 2710 and 2711 were used to explore differences between the optimized (modified) SM T procedure and three other sequential extraction schemes (i.e., the Tessier scheme, tlie Geological Survey of Canada scheme, and the original SM T scheme) (Sutherland and Tack, 2003). The experimental results revealed significant differences among the four schemes, even for those closely associated. Thus, the TEs released by the various SEPs in the different fractions must be assessed carefully because different trends may be obtained for the same metal species, soil-phase association, and environmental solid. 

Despite recent efforts toward settling operational conditions for metal and metalloid fractionation assays—in terms of concentration, pH, and temperature for each of the leaching reagents, sample weight/extractant volume ratio, extraction time, shaking protocol, analytical instrumentation, and phase separation method —conventional sequential extraction schemes lack automation and are inherently rather time consuming and laborious. This is the consequence of a number of steps needed for the separation, identification, and quantification of TEs in each fraction. For example, the SM T recommended protocol lasts more than 50 hours, whereas the operating time of Tessier s scheme approaches 20 hours. 

Shuman (1982, 1985), working on the speciation of Cu, Mn, Fe and Zn, modified the sequence of the extraction as exchangeable, oxidizable (organically bound), easily reducible (Mn oxides-bound), moderately reducible (amorphous Fe oxides-bound), strongly reducible (crystalline Fe oxides-bound), and residual. The low percentages of the oxidizable fractions obtained following the sequential extraction scheme of Shuman (1985) as compared to those obtained following the scheme of Tessier et al. (1979) were attributed to the lack of selectivity of the method used (Charlatchka et al, 1997). 

TABLE 14.4. The Sequential Extraction Scheme Suggested hy Tessier, Campbell, and Bisson (1979)... 

The analysis of samples extracted with various solvents will provide information on the most easily removed metal species, the less available, and the most refractory metal content, which is dissolved only by the strongest acid extractants. There are at least a dozen different published speciation schemes for metals in soils and sediments. Many are based on the pioneering work by Tessier et al. [125]. Most include releasing metals from carbonates and hydrous oxides with acids, and an oxidation step to destroy organic... 

One of the most frequently used protocols for selective extraction is the one of Tessier et al., with various possible modifications (38). The fraetions considered are usually the so-called exchangeable ones, bound to carbonates, bound to Fe and Mn oxides and hydroxides, bound to organie matter and sulphides (not distinguishable) and residual fractions. The differences among the various schemes used by different workers are primarily in the kind of reagents used to solubilize the various fractions. 

A simplified version of the scheme of Tessier et al. has been developed during the past years (40, 41). The scheme is made of three sequential extractions called A, B, C, which can leach respectively the exchangeable and carbonatic fraction (A), the reducible Fe-Mn hydroxides phase (B) and the organic matter together with the sulphides (C). The residual fraction is normally disregarded because total dissolution of the same samples is always performed, so that the residual fraction can be caleulated as the difference. Moreover, the residual fraction is the less important one from the viewpoint of bioavailability of trace metals. 

When using multifraction schemes, e.g., that of Tessier et al. (1979), the labels should refer to the extraction methods (e.g., mildly reducible). 

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