Colorimetric detection of Cu2+ in aqueous solution and on the test kit by 4-aminoantipyrine derivatives

A simple but novel compound of 4-aminoantipyrine derivative (NTBL) was synthesized and used for sensing Cu2+. Its applications in colorimetric detections of Cu2+ in aqueous solution and on the simple colorimetric paper-made test kits were performed. Upon addition of Cu2+, compound NTBL could give rise to a vivid color change from colorless to purple which was easily observed by the naked eye. However, compound NTBL did not show any observable change upon interaction with other metal ions. Under optimized experimental conditions, NTBL exhibits a dynamic response range for Cu2+ from 0 to 8.5 μM, with the detection limit of 2.14 × 10−7 M. The response of the colorimetric chemosensor for Cu2+ is reversible. Most importantly, both the color and absorbance changes of the chemosensor are remarkably specific for Cu2+ in the presence of other metallic cations (even those that exist in high concentration), which meets the selective requirements for biomedical and environmental monitoring application.