Sodium levulinate‐assisted detection of copper ions in aqueous solutions using UV–Vis quantification

Abstract The need to mitigate environmental pollution and the risks to human health posed by heavy metal contamination of water resources are among the main anthropogenic challenges. Although the analytical techniques used to detect and quantify metal ions are effective and well established, they still require complex and expensive instrumentation. Detection techniques based on colorimetric chemosensors have emerged as a simple and efficient alternative for on‐site analysis of metal ions. The aim of this study was to investigate the performance of sodium levulinate (NaLev) as an organic molecular sensor in a spectrophotometric procedure for the colorimetric detection of copper ions (Cu 2+ ) in aqueous solution. To this end, NaLev was first synthesized by hydrating levulinic acid with distilled water, using 18.5 mL of levulinic acid and 20 mL of distilled water, with the addition of 20 g of sodium hydroxide. The concentrations of Cu 2+ , NaLev, and the Cu 2+ –NaLev complex were determined by molecular absorption spectroscopy in the ultraviolet–visible (UV–Vis) region. The results showed that the addition of NaLev led to a significant increase in absorbance, accompanied by a gradual decrease in wavelength from 810 to 575 nm in samples without and with NaLev, respectively. The colour intensity of the Cu 2+ solution increased as the NaLev concentration rose. Concentrations as low as approximately 1 ppm, or even lower, could be detected using the proposed method. Thus, the NaLev colorimetric sensor for detecting Cu 2+ ions appears to represent a promising class of biologically based, heavy‐metal‐free colorimetric sensors.