Kinetic spectrophotometric determination of traces of iron(II)

A simple method for the selective and sensitive kinetic spectrophotometric determination of iron (II) is described. The method is based on the oxidati on reaction of reduced phenolphthalein by periodate in alkaline media. The change in absorbance was measured using the fixed time method. The effect o f different variables on the reaction was investigated and optimum conditio ns were obtained. The calibration curve was linear in the range 50-3000 ng/ mL, and a detection limit of 17 ng/mL was obtained. The relative standard d eviation of ten replicate determinations of 200 ng/mL of Fe(II) was 1.2%. T he determination of Fc(II) in the presence of a 50-fold amount of Fe(III) c ould be carried out.