Sensitive and selective aggregation based colorimetric sensing of Fe³⁺ via interaction with acetyl salicylic acid derived gold nanoparticles

Here we highlight a single pot green synthetic protocol for gold nanoparticles (AuNps) using acetyl salicylic acid (ASA) drug as reducing and capping agent. These nanoparticles were characterized using UV–Vis (UV–Vis) spectroscopy, Fourier Transform Infrared (FT-IR) Spectroscopy, X-ray diffractometry (XRD) and Atomic Force Microscopy (AFM). The estimated average size of AuNps was 33 nm. These ASA-AuNps were employed to develop a highly selective and sensitive colorimetric sensor for Fe3+ detection. This sensor responded linearly to Fe3+ in the range of 0.3–2.1 μmol L−1. The limit of detection (LOD) and limit of quantification (LOQ) of sensor was 0.051 and 0.17 μmol L−1 respectively. The response of the developed sensor to the interfering ions like Ni2+, Hg2+, Cd2+, Cr3+, Co2+, As3+, Pb2+, Fe2+ and Zn2+ was negligible. The sensor was used successfully to detect Fe3+ in real water samples collected from various locations of the Sindh River.