Rapid and selective detection of aluminum ion using 1,2,3-triazole-4,5-dicarboxylic acid-functionalized gold...

A highly selective, sensitive, rapid, low-cost, simple and visual colorimetric system for Al³⁺ ion detection was developed based on gold nanoparticles (AuNPs) modified with 1,2,3-triazole-4,5-dicarboxylic acid (TADA). The modified gold nanoparticles (TADA-AuNPs) were first prepared by sodium citrate (Na₃Ct) reduction of chloroauric acid (HAuCl₄) and then capped with a TADA ligand. Five TADA-AuNPs sensors were constructed with sodium citrate (Na₃Ct)/chloroauric acid (HAuCl₄) under different molar ratios. Results showed that the molar ratio of Na₃Ct/HAuCl₄, TADA-AuNPs concentration, pH range and detection time had obvious influences on the performance of this colorimetric method. The optimal detection conditions for Al³⁺ ions were as follows: Na₃Ct/HAuCl4 molar ratio of 6.4 : 1, 0.1 mM of TADA-AuNPs concentration, 4-10 pH range and 90 s of detection time. Under the optimal conditions and using diphenyl carbazone (DPC) as a Cr³⁺ masking agent, this colorimetric sensor exhibited outstanding time efficiency, selectivity and sensitivity for Al³⁺ detection. In particular, the detection limits of this sensor obtained via UV-vis and the naked eye were 15 nM and 1.5 μM, respectively, which were much lower than the current limit (3.7 μM) for drinking water in WHO regulation and better than the previous reports. Moreover, this colorimetric sensing system could be used to for on-site, trace level and real-time rapid detection of Al³⁺ in real water samples.