Colorimetric cadmium ion detection in aqueous solutions by newly synthesized Schiff bases

Abstract

Two newly synthesized Schiff bases DMCA and DMBA were used for selective detection of Cd 2+ over awide range of other metal ions in acetonitrile (ACN)/ Tris-HCl buffer (10 mM, pH 7.32, v/v 2:1). The sensors candetect $Cd^{2+}$ ions by colour changes from colourless to orange for DMBA and yellow to reddish for DMCA. Response ofthe probes towards metal ions was investigated by using UV-vis spectroscopy. The complex stoichiometry between thesensors, DMBA and DMCA, and $Cd^{2+}$ was found to be 2:1 and the binding constants were calculated to be 2.65 ×$10^{12}$$M^{-2}$and 4.95 ×$10^{12}$ $M^{-2}$, respectively. The absorbance-based detection limits of DMBA and DMCA were calculatedas 0.438 µM and 0.102 µM, respectively. The sensors were also successfully applied to real samples.