Fibre optic reflectance sensor for the determination of aluminium(III) in aqueous environment

An optical Al(III) sensor based on the use of Eriochrome cyanine R (ECR) immobilised on XAD-2 (styrene—divinylbenzene cross-linked copolymer) and diffuse reflectance spectrophotometry has been developed. A kinetic approach was used to quantify sensor response to Al(III) concentration in which the reflectance signal is measured at a fixed time interval of 3 min. Reproducible measurement of Al(III) was possible using the same probe (R.S.D. = 1.8%). Linear response was obtained for Al(III) concentration 1.3 × 10 −5−4.0 × 10 −4 M with limit of detection of 1.0 × 10 −5 M of the metal ion. The sensor was also used for the determination of Al(III) in aqueous samples and the results obtained were comparable to those obtained by graphite furnace atomic absorption spectrometry.