Application of Crosslinked Carboxymethyl Konjac Glucomannan in Speciation of Dissolved Fe(II) and Fe(III) in Water Samples

A new solid-phase extraction technique has been developed for the speciation of trace dissolved Fe(II) and Fe(III) in environmental water samples with a microcolumn packed with crosslinked carboxymethyl konjac glucomannan (CCMKGM) prior to its determination by flame atomic absorption spectrometry (FAAS). Various influencing factors on the separation and preconcentration of Fe(II) and Fe(III), such as the acidity of the aqueous solution, sample flow rate and volume, and eluent concentration and Volume, have been investigated systematically and optimized. Fe(III) could be quantitatively retained by CCMKGM in the pH range of 3.0-7.0, then the retained Fe(III) on the CCMKGM was eluted with 5.0 mol L-1 HCl after cleaning with 0.01 mol L-1 HCl to eliminate Fe(II) and determined by FAAS. Total Fe was determined after the oxidation of Fe(II) to Fe(III) by H2O2, and Fe(II) concentration was calculated by subtracting Fe(III) from total iron. The adsorption capacity of CCMKGM for Fe(III) was found to be as high as 162.3 mg g(-1). The detection limit (3 sigma) for Fe(III) was 1.5 mu g L-1 and the RSD was 3.5% (n = 11, c = 20 mu g L-1) with an enrichment factor of 50. The proposed method has been applied to the speciation of iron in water samples with satisfactory results. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 114: 3961-3966, 2009