New approach for the quantification of metallic species in healthcare products based on optical switching of a Schiff base possessing ONO donor set

Abstract

A new method is reported for the quantification of some metallic components of healthcare products utilizing a Schiff base chelator derived from 2-hydroxyacetophenone and ethanolamine. The Schiff base chelator recognizes some metallic species such as iron, copper and zinc (important components of some healthcare products), and cadmium (common contaminant in healthcare products) giving colorimetric/fluorimetric response. It coordinates with Fe2+/Fe3+ and Cu2+ ions via ONO donor set and switches the colour to bright red, green and orange, respectively. Similarly, it switches ‘ON’ a fluorometric response when coordinates with Zn2+ and Cd2+ ions. In the present approach, detailed studies on the colorimetric and fluorimetric response of ONO Schiff base is investigated in detail. The Job plot for the complexation of ONO switch with various metal ions suggested formation of 1:1 (metal-chelator) complex with Fe2+, Fe3+, and Cu2+ while 1:2 (metal-chelator) for Zn2+ and Cd2+ ions. The limit of detection, limit of quantification are 6.73, 18.0, 25.0, 0.65, 1.10μM and 27.0, 72.0, 100.0, 2.60 and 4.40μM for Fe2+, Fe3+, Cu2+, Zn2+ and Cd2+ ions, respectively. Under the optimized conditions, chelator was used for the quantification of important metals present in healthcare products via direct dissolution and furnace treatment during sample preparation. The results were found precise and accurate for both sample preparation techniques using the developed method.