Application of chromaticity characteristics for direct determination of trace aluminum with Eriochrome cyanine R by diffuse reflection spectroscopy

Eriochrome cyanine R (ECR) has been applied as immobilized reagent for the direct determination of aluminum by diffuse reflection spectroscopy. Sorpti on ability of aluminum species depends on the kind of solid support and inc reases in the following sequence: anionite AV-17 < silica gel < chromaton-N - super < cellulose. Chromaticity characteristics of the aluminum sorbates, namely, color Lightness (L), chromaticity coordinates (A, B), saturation ( S), hue (T), brightness (Y), whiteness (W), yellowness (G), and the total c olor difference (Delta E), indicate better sensitivity and precision than t he diffuse reflection coefficient. The experimental parameters (optical cha racteristics, acidity of aqueous solution, shaking time, volume of aqueous solution, etc.) affecting the sorption of aluminum species have been optimi zed. The detection limit is 0.004 mg/l for the aluminum complex immobilized on cellulose. The precision and accuracy of the proposed method was evalua ted with real samples, e.g. surface water, salt CH3COONa. (C) 2000 Elsevier Science B.V. All rights reserved.