SciELO - Scientific Electronic Library Online

vol.30 issue3Electrochemical evidence of sulfinic acid derivative as an intermediate in the reduction of aromatic sulfonyl chloride in an aprotic mediumThermal behaviour of 1,4-bis(3-carboxy-3-oxo-prop-1-en-1-yl)benzene compounds with Ag+ and Pb2+ author indexsubject indexarticles search
Home Pagealphabetic serial listing  

Services on Demand




Related links


Eclética Química

Print version ISSN 0100-4670On-line version ISSN 1678-4618


MARTINS, F. G. et al. Spectrophotometric study of iron oxidation in the iron(II)/thiocyanate/acetone system and some analytical applications. Eclet. Quím. [online]. 2005, vol.30, n.3, pp.63-71. ISSN 0100-4670.

The possibility of using thiocyanate to determine iron(II) and/or iron(III) in water-acetone mixture has been re-examined as part of a systematic and comparative study involving metallic complexes of pseudohalide ligands. Some parameters that affect the complete oxidation of the ferrous cations, their subsequent complexation and the system stability have been studied to optimize the experimental conditions. Our results show the viability and potentiality of this simply methodology as an alternative analytical procedure to determine iron cations with high sensitivity, precision and accuracy. Studies on the calibration, stability, precision, and effect of various different ions have been carried out by using absorbance values measured at 480 nm. The analytical curve for the total iron determination obeys Beer's law (r = 0.9993), showing a higher sensitivity (molar absorptivity of 2.10x104 L cm-1 mol-1) when compared with other traditional systems (ligands) or even with the "similar" azide ion [1.53x104 L cm-1 mol-1, for iron-III/azide complexes, in 70% (v/v) tetrahydrofuran/water, at 396 nm]. Under such optimized experimental conditions, it is possible to determine iron in the concentration range from 0.5 to 2 ppm (15-65% T for older equipments, quartz cells of 1.00 cm). Analytical applications have been tested for some different materials (iron ores), also including pharmaceutical products for anemia, and results were compared with atomic absorption determinations. Very good agreement was obtained with these two different techniques, showing the potential of the present experimental conditions for the total iron spectrophotometric determinations (errors < 5%). The possibility of iron speciation was made evident by using another specific and auxiliary method for iron(II) or (III).

Keywords : iron(II/III)-thiocyanate-acetone system; oxidation; spectrophotometric applications.

        · abstract in Portuguese     · text in English     · English ( pdf epdf )


Creative Commons License All the contents of this journal, except where otherwise noted, is licensed under a Creative Commons Attribution License