Photo-oxidation of acridine and acridine yellow in the presence of iron(III): determination of micro-amounts of iron, fluoride and phosphate

Abstract

Acridine (A) and acridine yellow (AY) are decolorised, in the presence of iron(III), by illumination with light of wavelength shorter than 360 nm. The decolorisation mechanism involves HO radicals, which are formed during the photo-excitation of hydrolysed iron(III) species. In the presence of oxygen, iron(III) acts as a catalyst in the photochemical process. The photo-oxidation of A and AY is followed by measuring the decrease in absorbance or fluorescence intensity of the dyes and linear calibration graphs in the range 0.05–7 p.p.m. of iron are obtained. Fluoride and phosphate ions strongly inhibit the iron(III)-catalysed photodecolorisation of A and AY and sensitive methods are proposed for their determination.