Determination of Trace Iron in Aqueous Samples by Its Catalytic Effect in Trinder’s Reaction in a Flow Injection System
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Date
2007-08
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Addis Ababa Universty
Abstract
A kinetic catalytic flow injection spectrophotometric method for the determination of
trace iron in aqueous samples has been proposed. It is based on the catalytic effect of iron
on the oxidative coupling of 4-AP and DCPS in the presence of hydrogen peroxide and in
slightly acidic medium to form quinine imine dye that has a maximum peak height at λmax
of 510 nm. The peak height observed at the flow through detector was linearly
proportional to iron (II, III) concentration over the range 1-20 μM.
In the proposed method, iron acts as a catalyst by changing its oxidation state from Fe2+
to Fe3+ and recycle Fe3+ to Fe2+. This recycling action of iron can magnify its effect for
the trace analysis in aqueous samples. Thus small amount of iron can be determined by
measuring the rate of the formation of the product.
After optimization of flow rate, pH of the carrier solution and concentration of each
reagents attempt was made to utilize the developed method for the determination of iron
content in commercially available bottled mineral waters (Aqua Addis, Aqua safe,
Abyssinia springs, and Highland). However, the method was not sensitive enough for
detection of traces of iron. Different activators were tested for their enhancement of
sensitivity but no increment in signal was observed.
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Keywords
Iron in Aqueous Samples