Inexpensive Alizarin Red S-based optical device for the simultaneous detection of Fe(III) and Al(III)

This work presents a simple, fast, disposable and low-cost colorimetric sensor for the simultaneous detection of Fe(III) and Al(III). It is obtained by fixing a classical dye, Alizarin Red S, on an inert solid support, i.e., a product of the washing powder market known as “Colour Catcher®” (here named under the acronym CC) generally used in the washing machine to prevent colour run problems. The device so obtained is called Aliz-CC@. Fe(III) and Al(III) interaction with the Alizarin Red S-based sensor, generates a change in the adsorption spectra of the fixed dye, allowing to highlight a naked-eye colour change. The relationship between the Fe(III) and Al(III) content and the colour change profiles of the sensor, is provided by using Partial Least Squares regression (PLS).