Colorimetric copper (Ⅱ) ions detection in aqueous solution based on the system of 3′3′5′5′-tetramethylbenzidine and AgNPs in the presence of Na2S2O3

Abstract

Herein, a colorimetric copper (Ⅱ) ion (Cu 2+ ) detection system based on the oxidization reaction of 3′3′5′5′-tetramethylbenzidine (TMB) and Ag(S 2 O 3 ) 2 3− (in aqueous solution) was designed. The detection system comprised TMB, silver nanoparticles (AgNPs) and thiosulfate (S 2 O 3 2− ). It was observed that AgNPs were unable to oxidize TMB to a blue color. While, Cu 2+ ions could effectively catalyze the S 2 O 3 2- -leaching system, thereby converting AgNPs to Ag(S 2 O 3 ) 2 3− . Similar to Ag (I), Ag(S 2 O 3 ) 2 3− catalyzed the color reaction of TMB. The colorimetric copper (Ⅱ) ion (Cu 2+ ) detection system was fabricated. Results showed that the optimal amounts of TMB and Na 2 S 2 O 3 were 800 and 400 μM, respectively, and the reaction time and temperature were 40 min and 25 °C, respectively. The range of curvature tendency was 1–100 μM, with a limit of detection of 100 nM. The detection system exhibited a high selectiveness for copper ions in an aqueous solution. Furthermore, this system shows remarkable promise for monitoring the aqueous quality.