FABRICATION AND CHARACTERIZATION OF ERIOCHROM CYANINE R ENTRAPPED SOL?GEL MEMBRANE FOR DETERMINATION OF ALUMINIUM(III)

membrane sensor was developed for Al(III) by the entrapment of Erichrome Cyanine R in sol?gel film. Evidence for successful fabrication of the membrane is provided by characterizations using UV?visible spectrophotometry (UV?vis). The red coloured sol?gel films turns pink on treatment with Al(III) containing samples, acidified with sulphuric acid. Linear calibration graph (R2 = 0.9980) for Al(III) was obtained in the range 40?120 ppb with a limit of detection of 7 ppb and this method is by far the most selective amongst the existing ones. The membrane also showed a reproducible result with RSD of 6% for 40 ppb of Al(III) with response time of 10 min and 95% confidence limit for determinations of 40 ± 2 ppb of Al(III). A possible sensing mechanism is also proposed. The method was applied for the determination of Al(III) in different types of environmental samples and the results obtained were in good correlation with those obtained by a standard method