EDTA is a non-specific reagent and major cations, such as iron,
calcium, and magnesium, are also extracted according to Eq. (3)
(Manouchehri and Bermond, 2009). At low concentration
(0.002 mol L1 EDTA in this work), the extractive reagent is no
longer in excess with respect to the total amounts of extractible
cations (Manouchehri et al., 2006).