ABSTRACT
The current literature contains a wide range of extractants that have been used to evaluate
different fractions of metals and metalloids in soils (Tessier et al. 1979; Ross 1994; Ure 1996;
Mihaljevic et al. 2003). These techniques fall into two categories: single or sequential
extractions. Although sequential extractions have gained considerable popularity, they do
have several drawbacks (Beckett 1989; Lo and Yang 1998; Shiowatana et al. 2001). From an
analytical point of view, sequential extractions may result in inconsistent results due to
reprecipitation of the elements of interest from one extractant to the next and errors caused
by adding the different fractions can lead to values that do not agree with analyses of total
metals. Perhaps the most important criticism of sequential extractions is that they are not
really specific for the intended fraction; examples of extractions that do not remove specific
and identifiable chemical forms are abundant in the literature (Beckett 1989; Mihaljevic
et al. 2003).
