Exploiting the use of 3,4-HPO ligands as nontoxic reagents for the determination of iron in natural waters with a sequential injection approach

Abstract

In this paper, the use of 3-hydroxy-4-pyridinone (3,4-HPO) chelators as nontoxic chromogenic reagents for iron determination is proposed. The potential application of these compounds was studied in a sequential injection system. The 3,4-HPO ligands used in this work were specially designed to complex iron(III) at physiologic pH for clinical applications. The developed sequential injection method enabled to study the reaction conditions, such as buffering and interferences. Then, to further improve the low consumption levels, a microsequential injection method was developed and effectively applied to iron determination in bathing waters using 3,4-HPO ligands. The formed iron complex has a maximum absorbance at 460nm. The advantage of using minimal consumption values associated with sequential injection, together with the lack of toxicity of 3,4-HPO ligands, enabled to present a greener chemistry approach for iron determination in environmental samples within the range 0.10–2.00mg Fe/L with a LOD of 7μg/L. The overall effluent production was 350μL corresponding to the consumption of 0.48mg of 3,4-HPO ligand, 0.11mg of NaHCO3, 0.16mg of HNO3 and 50μL of sample. Three reference samples were assessed for accuracy studies and a relative deviation <5% was obtained. The results obtained for the assessment of iron in inland bathing waters were statistically comparable to those obtained by the reference procedure.