Development of a new aminophenol-extended naphthoquinone-based chemical sensor with superior performance and easy accessibility for on-site and instantaneous determination of Cu²⁺ ions in selected environmental and food samples

A new colorimetric probe, based on aminophenol-extended naphthoquinone (APNQ), was synthesized by a straightforward one-step method. The chemical structures of APNQ and its copper complex were elucidated through the utilization of a range of spectroscopic techniques. The probe demonstrated noteworthy characteristics, including long-term stability, exceptional sensitivity to Cu²⁺ ions with a very fast and dual channels (colorimetric and spectrophotometric) response, and an impressive low detection limit of 16.74 ppb. Ratiometric determination of Cu²⁺ was successfully performed, yielding high recoveries and low relative standard deviations (RSD) across various water samples and fruit extracts. Moreover, the practical applicability of this method was demonstrated for on-site determination with smartphone applications, highlighting its superior sensitivity within the range of 3.33 × 10⁻⁷ to 1.07 × 10⁻³ molL⁻¹ compared to other probes in the literature.