Separation and preconcentration of fluoride at the ng ml(-1) level with a polymer complex of zirconium(IV) followed by potentiometric determination in a flow system
A. Yuchi et al., Separation and preconcentration of fluoride at the ng ml(-1) level with a polymer complex of zirconium(IV) followed by potentiometric determination in a flow system, ANALYT CHIM, 388(1-2), 1999, pp. 201-208
A complex of Zr(IV) with a hydrophilic resin having an iminodiacetic acid g
roup rapidly and selectively adsorbed fluoride from acidic media, which was
reversibly expelled on increase in pH. A Bow system consisting of a mini-c
olumn packed with this polymer complex for separation and preconcentration
of fluoride and an ion-selective electrode for detection gave the same peak
height for the same amount of fluoride, irrespective of the sample concent
ration and volume, and thus could be calibrated based on the chemical amoun
t; the detection limit defined by S/N=3 was 0.1 nmol. Use of the Bow system
decreased the lower limit for quantitative adsorption of fluoride down to
5 x 10(-8) M (compared with 1 x 10(-4) M by batch adsorption), and drastica
lly increased the tolerance limits of interfering cations and anions; even
the presence of a fourfold molar ratio of Al3+ was tolerated with cyclohexa
ne diamine tetraacetic acid as masking reagent. This system was applied to
the determination of fluoride in drinking water and concentrated brine. The
adsorption and desorption mechanism is discussed in detail. (C) 1999 Elsev
ier Science B.V. All rights reserved.