A Highly Selective and Sensitive Colorimetric Probe for Cu Determination in Aqueous Media Based on Derivative of Tryptanthrin.

A new colorimetric probe, based on tryptanthrin derivative (TR-A), has been successfully synthesized. The probe shows good selectivity and sensitivity for Cu over 12 competing metal ions in a 10 mM Tris-HCl buffer solution (pH 5.5). A significant peak at 623nm appears in the UV-Vis absorption of TR-A-Cu, and a noteworthy color change is observed with the naked eye from aquamarine blue to light orange. The interaction of TR-A and Cu are proven to form a 1:1 binding stoichiometry; this identifying is expected to be completed within 1 min. The probe with a limit of detection (16 nM, R = 0.9934) shows excellent potential to determine Cu in analysis systems.