J. Karhu et al., Determination of the solubility products of nitrilotriacetic acid, ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid, ANALYT CHIM, 380(1), 1999, pp. 105-111
A method is described for the determination of solubility products for poly
aminopolycarboxylic acids. The neutral protonated species of NTA (nitrilotr
iacetic acid), EDTA (ethylenediaminetetraacetic acid) and DTPA (diethylenet
riaminepentaacetic acid) were precipitated at low pH values. The amount of
precipitate was quantified by gravimetry and complexometric titrations with
a standard zinc(II) solution. The following solubility products were obtai
ned: S-H3NTA = 10(-16.36) S-H4EDTA - 10(-24.66) and S-H5DTPA = 10(-30.43).
Those values were used for theoretical calculation and optimization of the
precipitation processes of NTA, EDTA and DTPA at different pH values in the
absence and presence of the metal ions Fe3+ and Mn2+. (C) 1999 Elsevier Sc
ience B.V. All rights reserved.