Selection of the sample composition for the selective preconcentration of some platinum group metal ions by Donnan dialysis

On-Line pre-concentration of Cr(III) and Mn(II) in FI-FAAS: A critical study involving interference effects and analytical use of an immobilized 8-hydroxyquinoline minicolumn

“…Also, the interference caused by Ca(II) was greater than that of Cu(II) and Fe(III), which form stronger complexes with quinolinate (logβ 1 , 12.2 and 12.3 respectively) [31], probably because the concentration of Ca(II) is much higher (fifteen-fold) and affects complex formation. At this point, these results seemed quite surprising; however, a similar effect was previously described by Brajter and Slonawska when using the chelating ion exchanger Cellex-P, a cellulose dibasic phosphate ester [32]. These authors observed that at high concentrations of Ca(II) (e.g., 30 mg L -1 ), the recoveries of Cd(II), Cu(II), Mn(II), Ni(II), Pb(II), and Zn(II) at 0.1 mg L -1 in water samples were improved, that is, their retention efficiency was higher and Ca(II) retention was 5% only [32].…”

“…At this point, these results seemed quite surprising; however, a similar effect was previously described by Brajter and Slonawska when using the chelating ion exchanger Cellex-P, a cellulose dibasic phosphate ester [32]. These authors observed that at high concentrations of Ca(II) (e.g., 30 mg L -1 ), the recoveries of Cd(II), Cu(II), Mn(II), Ni(II), Pb(II), and Zn(II) at 0.1 mg L -1 in water samples were improved, that is, their retention efficiency was higher and Ca(II) retention was 5% only [32]. In the present work at least three factors might have played a role and should be considered in the aforementioned Cr(III) recovery: i) the optimum pH for the retention of Cr(III) by the chelating ion-exchange resin (pH 9.2-9.8); ii) the chemical form of the immobilized 8-HQ; and iii) the effect of Ca(II) and the formation of hydroxo-complexes.…”