A very simple, highly sensitive and selective method for the determination of trace amounts of Cr3+ in real systems using the solvatochromic properties of a rhodamine-based sensor has been developed. This solvatochromic-based sensor is established using commercially available rhodamine dissolved in different solvents to produce rhodamine lactone (RhoL) via the rhodamine lactone–zwitterion equilibrium. Complexation studies using fluorescence spectroscopy showed that RhoL exhibited the highest colorimetric and fluorescence selectivity and sensitivity to Cr3+ in aqueous medium when compared to other metal ions. Importantly, RhoL could directly and rapidly detect Cr3+ through filter paper without resorting to additional instrumental analysis.
