Abstract
Iron (III) reacts with an excess of Xylenol Orange to form 1:1 and 1:2 complexes with their absorption maxima at 545 and 500 mμ, respectively, while only a 1:1 complex with its absorption maximum at about 586 mμ is formed when an excess of iron is present. The molar extinction coefficients and the apparent formation constants of these complexes were spectrophotometrically determined.
As little as 3μg/25ml of iron was determined successfully with any one complex of the former two, and as little as 0.025μmol/25ml and of Xylenol Orange with the latter. The absorbance in every case conforms well to Beer's law.
